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Glossary

  • 1,25(OH)2D

    1,25-dihydroxyvitamin D

  • 123I-MIBG

    123I-meta-iodobenzylguanidine

  • 2,5-HD

    2,5-hexanedione

  • 2-D PAGE

    In this technique, the proteins are separated in two dimensions (by isoelectric focusing and mass), and a pattern is achieved that places each of the 2000 proteins of a cell at a grid reference point. By reference to established databases, individual prot

  • 2-D polyacrylamide gel electrophoresis

    In this technique, the proteins are separated in two dimensions (by isoelectric focusing and mass), and a pattern is achieved that places each of the 2000 proteins of a cell at a grid reference point. By reference to established databases, individual proteins can be identified as the product of genes that have been sequenced.

  • 2-DGE

    2-dimensional gel electrophoresis

  • 24-hour sleep-wake pattern

    A person's clock hour schedule of bedtime and arise time as well as nap behavior; may also include time and duration of sleep interruptions. See Sleep-Wake Cycle; Circadian Rhythm; Sleep Log.

  • 3,4-DAP

    3,4-Diaminopyridine

  • 3-OMD

    3-O-methyldopa

  • 5,10-Methylenetetrahydrofolate reductase

    An enzyme that reduces 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate.

  • 5-HIAA

    5-hydroxyindoleacetic acid

  • 5-HT

    5-hydroxytryptamine

  • 5-LO

    5-lipoxygenase

  • 6-Hydroxydopamine

    A potent neurotoxin.

  • 6-OHDA

    A potent neurotoxin.

  • 6-Pyruvoyltetrahydropterin synthase deficiency

    A widely variant autosomal recessive disorder of tetrahydrobiopterin metabolism resulting in reduced synthesis of biogenic amine neurotransmitters. Symptoms often include poor sucking, decreased spontaneous movements, floppiness, microcephaly, low birth weight, and early appearance of neurologic signs in the neonatal period. Variant forms of 6-pyruvoyltetrahydropterin synthase have been described in which the neurologic signs are either minor or absent. In these there are normal concentrations of homovanillic acid and 5-hydroxyindoleacetic acid in CSF, often normal EEGs, and none of the signs of abnormal serotonin and catecholamine metabolism. However, there has been a report of an atypical form of 6-pyruvoyltetrahydropterin synthetase deficiency progressing to give a central phenotype. Greatly decreased urinary biopterins and increased neopterins, as well as increased levels of phenylalanine, are seen in both forms.

  • A-CC

    agenesis of the corpus callosum

  • AADC

    amino acid decarboxylase

  • AAEE

    American Association of Electromyography and Electrodiagnosis

  • AAV

    adeno-associated virus

  • ABC

    adenosine triphosphate-binding cassette

  • ABC transporter

    Over 80 related proteins involved in the transport of proteins, peptides, amino acids, inorganic ions, and certain drugs in both prokaryocytes and eukaryocytes. All ABC transporters possess significant sequence identity and a similar topology, consisting of a hydrophobic domain located in the membrane and two adenosine triphosphate-binding domains on the cytoplasmic surface of the membrane. The deduced protein structure of adrenoleukodystrophy gene shares unexpected homology to ABC transporter gene. They are also referred to as traffic adenosine triphosphatases, as they require ATP as an energy source.

  • ABC transporters

    Over 80 related proteins involved in the transport of proteins, peptides, amino acids, inorganic ions, and certain drugs in both prokaryocytes and eukaryocytes. All ABC transporters possess significant sequence identity and a similar topology, consisting of a hydrophobic domain located in the membrane and two adenosine triphosphate-binding domains on the cytoplasmic surface of the membrane. The deduced protein structure of adrenoleukodystrophy gene shares unexpected homology to ABC transporter gene. They are also referred to as traffic adenosine triphosphatases, as they require ATP as an energy source.

  • Abductor spasmodic dysphonia

    The result of the vocal cords being pulled apart, creating a weak, breathy voice.

  • ABR

    auditory brainstem response

  • ACA

    anterior carotid artery

  • Acalculia

    Acquired disorder in computational ability.

  • Acanthocytosis

    A description of the blood film where the majority of red blood cells are acanthocytes (red blood cells with multiple spiny cytoplasmic projections).

  • accelerated long-term forgetting

    A memory disorder in which information that is learned and retained normally over standard intervals (approximately 30 min) is forgotten at an abnormally rapid rate thereafter.

  • ACh

    acetylcholine

  • AChEH

    acetylcholinesterase subunits of type H

  • AChET

    acetylcholinesterase subunits of type T

  • AChR

    acetylcholine receptor

  • Achromasia

    Lack of normal pigmentation of the skin, cachectic pallor.

  • Achromasic

    Having little or no coloration after treatment with histologic stain.

  • Achromatic

    Having little or no coloration after treatment with histologic stain.

  • Achromatopsia

    The total lack of color perception in which all the colors of the spectrum are seen as black, grey, or white.

  • Acid-fast bacillus

    The capacity of the bacillus, when stained with red carbol fuschin dye, to retain its red color when treated with acid.

  • ACNU

    1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea

  • Acquired cytomegalovirus

    Viral infection by a member of the herpes virus group that causes a wide range of diseases, transmitted by sexual contact, body secretions, blood transfusions, or organ transplants. Those who are immunodeficient are particularly susceptible.

  • ACR/EULAR

    American College of Rheumatology/European Ligue Against Rheumatism

  • Acrocephalopolysyndactyly

    A congenital syndrome characterized by oxycephaly and brachysyndactyly of the hands, polydactyly of the feet, and mental retardation. Also known as Carpenter syndrome.

  • Acrocephalopolysyndactyly type I

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • Acrocephalosyndactyly type III

    A condition in which there is coronal synostosis (unilateral or bilateral), facial asymmetry (particularly in individuals with unicoronal synostosis), ptosis, and characteristic appearance of the ear (small pinna with a prominent crus). Syndactyly of digits two and three of the hand is variably present. Also known as Saethre-Chotzen syndrome.

  • Acrocephalosyndactyly type V

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • acrocephaly

    A congenital abnormality of the skull in which the top of the head assumes a conical or pointed shape because of premature closing of the lambdoid and coronal sutures. Also known as acrocephaly.

  • ACS

    acrocallosal syndrome

  • ACTH

    adrenocorticotropic hormone

  • Actigraph

    A biomedical instrument for the measurement of body movement.

  • Actigraphs

    A biomedical instrument for the measurement of body movement.

  • Activated protein C resistance

    A hypercoagulable state, usually caused by an inherited mutation in coagulation factor V, termed "factor V Leiden."

  • Active myofascial trigger point

    A focus of hyperirritability in a muscle of its fascia that is symptomatic with respect to pain; it causes a pattern of referred pain at rest and/or on motion that is specific for that muscle.

  • Active myofascial trigger points

    A focus of hyperirritability in a muscle of its fascia that is symptomatic with respect to pain; it causes a pattern of referred pain at rest and/or on motion that is specific for that muscle.

  • Active sleep

    A term used in the phylogenetic and ontogenetic literature for the stage of sleep that is considered to be equivalent to REM sleep.

  • Activin

    One of the two gonadal glycoproteins related to transforming growth factor-beta, and is important in embryonal development.

  • Acute alcoholic myopathy

    Acute muscle injury caused by sever alcoholic binges in alcoholics, leading to swollen painful muscles and rhabdomyolysis.

  • Acute disseminated encephalomyelitis

    Generally used to describe an acute, severe, monophasic event following vaccination of viral infection by 6 to 24 days. The process is multifocal and demyelinating and may be hemorrhagic.

  • Acute multiple sclerosis, Marburg variant

    Part of the spectrum of multiple sclerosis initially described by Marburg in 1906, which included examples of lesions with bands of preserved myelin and disrupted myelin.

  • ACY1

    Aminoacylase 1

  • ADC

    apparent diffusion coefficient

  • Add-on trial

    Clinical trials in which test medications are added to already present regimens.

  • Add-on trials

    Clinical trials in which test medications are added to already present regimens.

  • Adductor spasmodic dysphonia

    The result of the vocal cords' hyperadducting, creating a strained, choked voice.

  • ADEM

    acute disseminated encephalomyelitis

  • ADH

    antidiuretic hormone

  • ADHAPS

    alkyl-dihydroxyacetonephosphate synthase

  • ADHD

    attention deficit hyperactivity disorder

  • ADP

    adenosine 5'diphosphate

  • adrenoleukodystrophy protein

    An ATP-binding cassette (ABC) transporter in the human peroxisome membrane. It is defective in X chromosome-linked adrenoleukodystrophy.

  • Affective disorder

    Any mental disorder in which a disturbance of the affect is predominant (eg, major depression, bipolar affective disorder).

  • aFP

    alpha-fetoprotein

  • AgNOR

    silver-staining nucleolar organizer region

  • Agnosia

    Failure to recognize environmental stimuli despite intact sensory function.

  • Agrammatism

    Failure to use grammatical rules, typified by producing mainly nouns and verbs, without modifying them according to their functions in sentences.

  • Agraphesthesia

    The inability to name isolated letters or numerals traced on the skin, usually on the palm, without viewing.

  • Agraphia

    Acquired inability to write due to cognitive dysfunction.

  • Agraphic acalculia

    Disturbance in calculation abilities resulting from a defect in the normal ability to write.

  • AHI

    apnea hypopnea index

  • AICA

    anterior inferior cerebellar artery

  • AIDP

    acute inflammatory demyelinating polyradiculoneuropathy

  • Air conduction

    Transmission of sound to the cochlea through air to the external and middle ears.

  • Akathisia

    Inner sense of restlessness relieved by volitional movement of the leg.

  • Akinesia

    Absence of, but more accurately the paucity of, spontaneous unconscious movements.

  • Alagille syndrome

    A genetic disorder that affects the liver, heart, and other systems of the body. Problems associated with the disorder generally become evident in infancy or early childhood. The disorder is inherited in an autosomal dominant pattern, and the estimated prevalence is 1 in every 70,000 live births. Also known as Alagille syndrome.

  • Albright hereditary osteodystrophy

    A genetic disorder that resembles hypoparathyroidism (lowered levels of parathyroid hormone) but is caused by a lack of response to parathyroid hormone rather than a deficiency in the hormone itself. Also known as Albright hereditary osteodystrophy.

  • Albright's hereditary osteodystrophy

    A genetic disorder that resembles hypoparathyroidism (lowered levels of parathyroid hormone) but is caused by a lack of response to parathyroid hormone rather than a deficiency in the hormone itself. Also known as Albright hereditary osteodystrophy.

  • Alcohol-related neurodevelopmental disorder

    A disorder of neurodevelopment due to prenatal exposure to alcohol. In this disorder, the growth retardation and facial characteristics of fetal alcohol syndrome are not present. The neurodevelopmental abnormalities most often include deficits in attention and learning.

  • ALDP

    Adrenoleukodystrophy protein

  • ALDRP

    Adrenoleukodystrophy-related protein

  • Alexic acalculia

    Disturbance in calculation abilities resulting from a defect in the normal ability to read.

  • Alkaptonuria

    A rare inherited disorder of metabolism, characterized by urine that turns black when exposed to air. Another characteristic is the development of arthritis in adulthood. Also known as ochronosis or homogentisic acid oxidase deficiency.

  • Allele

    One member of a pair or series of genes that occupies a specific location on a specific chromosome.

  • Alleles

    One member of a pair or series of genes that occupies a specific location on a specific chromosome.

  • Allodynia

    (From allo, other, and dynia, tenderness) Pain due to a stimulus that does not normally provoke pain.

  • Alpha activity

    An alpha EEG wave or sequence of waves with a frequency of 8-13 Hz.

  • Alpha infiltration

    A brief superimposition of EEG alpha activity on sleep activities during a stage of sleep.

  • Alpha insertion

    A brief superimposition of EEG alpha activity on sleep activities during a stage of sleep.

  • Alpha interruption

    A brief superimposition of EEG alpha activity on sleep activities during a stage of sleep.

  • Alpha intrusion

    A brief superimposition of EEG alpha activity on sleep activities during a stage of sleep.

  • Alpha rhythm

    An EEG rhythm with a frequency of 8-13 Hz in human adults, which is most prominent over the parieto-occipital cortex when the eyes are closed. The rhythm is blocked by eye opening or other arousing stimuli. It is indicative of the awake state in most normal individuals. It is most consistent and predominant during relaxed wakefulness, particularly with reduction of visual input. The amplitude is variable, but typically is below 50 'V in the adult. The alpha rhythm of an individual usually slows by 0.5-1.5 Hz and becomes more diffuse during drowsiness. The frequency range also varies with age; it is slower in children and older age-groups relative to young and middle-aged adults.

  • Alpha rhythms

    An EEG rhythm with a frequency of 8-13 Hz in human adults, which is most prominent over the parieto-occipital cortex when the eyes are closed. The rhythm is blocked by eye opening or other arousing stimuli. It is indicative of the awake state in most normal individuals. It is most consistent and predominant during relaxed wakefulness, particularly with reduction of visual input. The amplitude is variable, but typically is below 50 'V in the adult. The alpha rhythm of an individual usually slows by 0.5-1.5 Hz and becomes more diffuse during drowsiness. The frequency range also varies with age; it is slower in children and older age-groups relative to young and middle-aged adults.

  • Alpha sleep

    Sleep in which alpha activity occurs during most, if not all, sleep stages.

  • Alpha-delta sleep

    Sleep in which alpha activity occurs during slow wave sleep. Because alpha-delta sleep is rarely seen without alpha occurring in other sleep stages, the term alpha sleep is preferred.

  • Alpha-dystroglycan

    A component of the dystroglycan complex that is involved in the pathogenesis of muscular dystrophies.

  • Alpha-ketoglutarate dehydrogenase deficiency

    A rare autosomal recessive disorder of the enzyme responsible for oxidation of alpha-ketoglutarate to succinyl CoA in the Krebs cycle. The defect can occur in the E2 subunit, dihydrolipoyl transacylase (chromosome 14), causing initial hypotonia, motor delay, and acidosis followed by hypertonicity and choreoathetoid movements with variable seizures and hepatomegaly. More commonly a more severe disorder involving the alpha-ketoglutarate dehydrogenase E3 subunit, dihydrolipoyl dehydrogenase (chromosome 7), is effected. The E3 subunit is identical to that of pyruvate dehydrogenase and branched-chain alpha-ketoacid dehydrogenase, and its inactivation leads to more widespread derangements of both pyruvate and branched-chain amino acid metabolism.

  • Alpha-mannosidosis

    Alpha-mannosidase deficiency linked to chromosome 19, causing lysosomal accumulation of manno-oligosaccharides in all tissues. Type 1 is more severe and occurs in the first year of life, with psychomotor and mental retardation, hypotonia, hepatosplenomegaly, coarse facies, dysostosis multiplex, frequent infections, and neural deafness. Type 2 is milder, with infant to adult onset, speech and hearing deficits appearing in adolescence, hypotonia, tremor, dysequilibrium, and mild to moderate mental retardation.

  • Alpha-oxidation

    The process by which only the carboxyl carbon of a fatty acid is removed, shortening the chain by one carbon. Although still under debate, it is likely that this process takes place in peroxisomes.

  • ALS-FTD

    amyotrophic lateral sclerosis-frontotemporal dementia

  • ALS-PDC

    amyotrophic lateral sclerosis-parkinsonism dementia complex

  • ALSP

    axonal spheroids and pigmented glia

  • ALT

    alanine aminotransferase

  • ALTE

    apparent life-threatening event

  • Alternating programs

    A test to detect perseveration, in which the patient must copy and extrapolate a line drawing with alternating shapes (eg, a triangle followed by a square).

  • AMD

    acid maltase deficiency

  • Amebic meningoencephalitis

    Inflammation of the brain and its coverings by a parasitic protozoa.

  • Ammonia metabolism

    Ammonia is derived mainly from proteins, amino acids, amines, and nucleic acid, mainly in the gastrointestinal tract, kidneys, muscles, brain, liver, and red blood cells. In catabolism muscular ammonia is in the foreground, and the purine nucleotide cycle in muscles and other tissues plays an important role. Two-thirds of the ammonia comes from the gut from precursors of glutamine and urea. Colon bacteria synthesize one-third to one-half of intestinal ammonia, and the rest comes from metabolic products and to some extent from the reabsorption of nutritional ammonia. Even in the absence of bacteria in the intestine, ammonia is released by enzymatic hydrolysis of urea. Gut-derived ammonia in the liver is converted largely to urea and to a lesser extent, glutamine. Ammonia that escapes the action of ammonia-utilizing enzymes in the liver or is released into the circulation from systemic metabolic processes is metabolized largely to glutamine in the extrahepatic organs: brain, skeletal muscles, heart, adipose tissue, and lungs. The gut takes up glutamine released by these organs where it is an energy source. Ultimately the nitrogen is excreted, mostly as urea.

  • AMP

    adenosine monophosphate (adenylic acid)

  • AMPA

    alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid

  • AMPD

    adenosine monophosphate (adenylic acid) deaminase

  • AMPDA

    adenosine monophosphate (adenylic acid) deaminase

  • Amphetamine look-alike

    Drugs with sympathomimetic action that are available for over-the-counter sale.

  • Amphetamine look-alikes

    Drugs with sympathomimetic action that are available for over-the-counter sale.

  • Amphetamine psychosis

    Constellation of psychiatric symptomatology associated with stimulant use.

  • ANA

    antinuclear antibodies

  • analgesia

    Absence of pain in response to stimulation which would normally be painful.

  • Anarithmetia

    Acquired inability in understanding and using numerical concepts, usually associated with left posterior parietal damage.

  • ANCA

    antineutrophil cytoplasmic autoantibodies

  • ANCL

    adult neuronal ceroid lipofuscinosis

  • Anergia

    Lack of energy.

  • Aneurysm

    A localized dilatation of a blood vessel; a ballooning out of arterial wall.

  • Aneurysmectomy

    Excision of an aneurysm.

  • Aneurysmorrhaphy

    Repair of an aneurysm.

  • Angiography

    A procedure in which a catheter is introduced into the vessel, and intravenous or intra-arterial contrast is infused through the vessel, which will show the anatomy of vessels and any potential malformation, variation, stenosis etc.

  • Angiokeratoma

    Pink or red skin telangiectasia, papule, or small nodule that can undergo hyperkeratosis and tends to be diffuse in Fabry disease.

  • Angiolipoma

    These are extradural lipomas; 95% are located in the spine and they are frequently associated with vascular malformations.

  • Angiolipomas

    These are extradural lipomas; 95% are located in the spine and they are frequently associated with vascular malformations.

  • ANHE

    acute necrotizing hemorrhagic encephalopathy

  • Anhedonia

    Lack of feelings of pleasure.

  • Anhidrosis

    Lack of sweating.

  • ANNA-1

    type 1 antineuronal nuclear antibodies

  • ANNA-2

    type 2 antineuronal nuclear antibodies

  • Anomia

    Impaired ability to name objects or retrieve words.

  • Anosmia

    Loss of the sense of smell.

  • Anosognosia

    Unawareness of physical deficits, most often seen with lesions of the right parietal lobe. It may include denial of ownership of a limb.

  • Anoxic seizure

    A nonepileptic attack arising as a consequence of a sudden decrease in cerebral perfusion of oxygenated blood.

  • Anoxic-epileptic seizure

    An epileptic seizure precipitated by an anoxic seizure.

  • Anterograde amnesia

    Loss of access to memories of ongoing events.

  • Anti-MAG antibodies

    Antibodies that react with MAG and are thought to cause neuropathy. They are usually monoclonal antibodies of the IgM type.

  • Anticardiolipin antibody

    An antiphospholipid antibody that recognizes bovine cardiolipin in a molecular complex with beta2-glycoprotein I.

  • Antidromic

    Conducting impulses in the opposite direction of normal.

  • Antineuronal antibodies

    Antibodies triggered by b-hemolytic group A streptococcus that cross-react with basal ganglia epitopes.

  • Antineutrophil cytoplasmic antibodies

    Autoantibodies directly against neutrophilic antigens. The myeloperoxidase ANCA stains leukocyte perinuclear cytoplasm diffusely and is associated with Churg-Strauss syndrome, whereas the proteinase 3 ANCA stains the cytoplasm diffusely and is associated with Wegener granulomatosis. The pathogenic role of these antibodies is not conclusively proven, but in vitro they are able to elicit neutrophil granule release, and their titers may correlate with disease activity.

  • Antineutrophil cytoplasmic antibody

    Autoantibodies directly against neutrophilic antigens. The myeloperoxidase ANCA stains leukocyte perinuclear cytoplasm diffusely and is associated with Churg-Strauss syndrome, whereas the proteinase 3 ANCA stains the cytoplasm diffusely and is associated with Wegener granulomatosis. The pathogenic role of these antibodies is not conclusively proven, but in vitro they are able to elicit neutrophil granule release, and their titers may correlate with disease activity.

  • Antineutrophil cytoplasmic antibody (ANCA)

    Autoantibodies directly against neutrophilic antigens. The myeloperoxidase ANCA stains leukocyte perinuclear cytoplasm diffusely and is associated with Churg-Strauss syndrome, whereas the proteinase 3 ANCA stains the cytoplasm diffusely and is associated with Wegener granulomatosis. The pathogenic role of these antibodies is not conclusively proven, but in vitro they are able to elicit neutrophil granule release, and their titers may correlate with disease activity.

  • Antiphospholipid antibody syndrome

    A syndrome characterized by arterial or venous thrombosis, thrombocytopenia, recurrent fetal loss, livedo reticularis, and the presence of antiphospholipid antibodies.

  • Antithrombin III deficiency

    A hypercoagulable state caused by inherited deficiency of antithrombin III.

  • Antley-Bixler syndrome

    A rare genetic disorder that is primarily characterized by distinctive malformations of the head and facial (craniofacial) area and additional skeletal abnormalities. The disorder is typically associated with premature closure of the fibrous joints (cranial sutures) between particular bones of the skull (craniosynostosis). Many affected infants and children also may have a prominent forehead, underdeveloped midfacial regions (midfacial hypoplasia), protruding eyes (proptosis), and other craniofacial abnormalities. Additional skeletal malformations are usually present, such as fusion of certain adjacent bones of the arms (e.g., radiohumeral or radioulnar synostosis); long, thin fingers and toes (arachnodactyly); and bowing of the thigh bones. In addition, certain joints may become permanently flexed or extended in fixed postures (joint contractures), resulting in restricted movements.

  • Anton syndrome

    Bilateral infarction of the striate cortex leads to cortical blindness. Some cortically blind patients who do not recognize or will not admit that they cannot see have Anton syndrome.

  • APD

    afferent pupillary defect

  • Apert syndrome

    Acrocephalosyndactyly with the second through fifth digits fused into one mass with a common nail, often accompanied by moderately severe acne vulgaris on the forearms. Also known as Apert syndrome.

  • Apert's syndrome

    Acrocephalosyndactyly with the second through fifth digits fused into one mass with a common nail, often accompanied by moderately severe acne vulgaris on the forearms. Also known as Apert syndrome.

  • Apgar

    Evaluation of physical status of a newborn that rates its hearing rate, respiratory effort, muscle tone, response stimulation, and skin color. A score between 8 and 10 indicates best condition.

  • Apgar score

    Evaluation of physical status of a newborn that rates its hearing rate, respiratory effort, muscle tone, response stimulation, and skin color. A score between 8 and 10 indicates best condition.

  • Aphasic acalculia

    Disturbance in calculation abilities resulting from a language defect.

  • Aphasic agraphia

    A handwriting disorder consisting of impaired spelling or incorrect word production, not due to impaired motor control, sensory loss, educational experience, or failure to understand the task.

  • Aphemia

    Articulatory speech disorder without aphasia.

  • aPL

    antiphospholipid antibody

  • Apnea

    Cessation of airflow at the nostrils and mouth lasting at least 10 seconds. There are three types of apnea: obstructive, central, and mixed. Obstructive apnea is secondary to upper airway obstruction; central apnea is associated with a cessation of all respiratory movements; mixed apnea has both central and obstructive components.

  • Apnea index

    The number of apneic episodes (obstructive, central, and mixed) per hour of sleep as determined during all-night polysomnography. Sometimes a separate obstructive apnea index or central apnea index is stated.

  • Apnea-hypopnea index

    The number of apneic episodes (obstructive, central, and mixed) plus hypopneas per hour of sleep as determined by all-night polysomnography.

  • Apneas

    Cessation of airflow at the nostrils and mouth lasting at least 10 seconds. There are three types of apnea: obstructive, central, and mixed. Obstructive apnea is secondary to upper airway obstruction; central apnea is associated with a cessation of all respiratory movements; mixed apnea has both central and obstructive components.

  • apoE

    apolipoprotein E epsilon

  • apoE4

    apolipoprotein E epsilon4

  • Apolipoprotein

    The protein component on lipoproteins.

  • Apoptosis

    (Greek, apo=away from, ptosis=fall) Single deletion of scattered cells by fragmentation into membrane-bound particles that are phagocytosed by other cells; believed to be due to programmed cell death.

  • apparent life-threatening event

    Frightening signs identified by a caretaker, which can include apnea, cyanosis or pallor, altered muscle tone, choking, or gagging

  • Apparent life-threatening event (ALTE)

    Frightening signs identified by a caretaker, which can include apnea, cyanosis or pallor, altered muscle tone, choking, or gagging

  • Apparent life-threatening events

    Frightening signs identified by a caretaker, which can include apnea, cyanosis or pallor, altered muscle tone, choking, or gagging

  • Apractic agraphia

    Segmental ideomotor apraxia observed in difficulties in performing the movements to write letters and words.

  • Apraxia

    Inability to perform familiar, learned purposeful movements in the absence of motor or sensory impairment.

  • Apraxic agraphia

    Impaired handwriting due to poor production of required movement sequences or spatial configurations, not due to weakness, generalized incoordination, dystonia, sensory loss, linguistic disturbance, or failure to understand the task. The nondominant hand of most healthy people may be said to show apraxic agraphia when writing.

  • Aprosodia

    Communication disorder involving impaired modulation or comprehension of vocal tone.

  • APTT

    activated partial thromboplastin time

  • AQP4

    aquaporin-4

  • AR

    autosomal recessive

  • Ara-C

    cytarabine

  • Arachnoid

    The middle layer of meninges, bounded externally by the dura and containing the cerebrospinal fluid-filled subarachnoid space.

  • Arachnoiditis

    A condition of fibrous proliferation within the subarachnoid space leading to loculations of CSF, back pain, and sometimes spinal cord compression.

  • ARBD

    alcohol-related birth defect

  • Arbovirus

    Acronym for arthropod-borne viruses, which are members of a group of animal viruses that multiply in an arthropod and are transmitted to a vertebrate host.

  • Arboviruses

    Acronym for arthropod-borne viruses, which are members of a group of animal viruses that multiply in an arthropod and are transmitted to a vertebrate host.

  • Arena virus

    A group of RNA-containing viruses with a rodent reservoir.

  • Arg

    arginine

  • ARIA

    acetylcholine receptor-inducing activity

  • Arise time

    The clock time that an individual gets out of bed after the final awakening of the major sleep episode. Distinguished from final wake-up.

  • ARND

    alcohol-related neurodevelopmental disorder

  • Arnold's nerve

    The auricular branch of the vagus nerve.

  • Arousal disorder

    A parasomnia disorder presumed to be due to an abnormal arousal mechanism. Forced arousal from sleep can induce episodes. The "classical" arousal disorders are sleepwalking, sleep terrors, and confusional arousals.

  • arousal disorders

    A parasomnia disorder presumed to be due to an abnormal arousal mechanism. Forced arousal from sleep can induce episodes. The "classical" arousal disorders are sleepwalking, sleep terrors, and confusional arousals.

  • Arrhinencephaly

    Absence of olfactory bulbs and olfactory cortex.

  • Arteriohepatic dysplasia

    A genetic disorder that affects the liver, heart, and other systems of the body. Problems associated with the disorder generally become evident in infancy or early childhood. The disorder is inherited in an autosomal dominant pattern, and the estimated prevalence is 1 in every 70,000 live births. Also known as Alagille syndrome.

  • Arteriovenous malformation

    The most common of the vascular malformations to cause symptoms. Most often they present as hemorrhage, but they may also present with seizure or focal deficit. They represent an aberrant connection between the arteriole and venous circulation with bypass of the capillary system.

  • Arteriovenous malformations

    The most common of the vascular malformations to cause symptoms. Most often they present as hemorrhage, but they may also present with seizure or focal deficit. They represent an aberrant connection between the arteriole and venous circulation with bypass of the capillary system.

  • Arthropod

    Organism with an exoskeleton and paired, jointed legs, including insects, spiders, and ticks.

  • arthropods

    Organism with an exoskeleton and paired, jointed legs, including insects, spiders, and ticks.

  • arylsulfate beta deficiency

    Autosomal recessive mucopolysaccharidosis caused by arylsulfate beta deficiency, with dermatan sulfate excreted in the urine. Hurler-like symptoms are seen, with coarse facial features, dysotosis multiplex, short stature, corneal clouding, hepatosplenomegaly, hearing loss, and normal intelligence. Life span is dependent on extent of cardiomyopathy and valvular disease. Also known as mucopolysaccharidosis VI and arylsulfate beta deficiency.

  • ASA

    argininosuccinic acid (or arylsulfatase A)

  • Ascending myelopathy

    A disease causing necrosis of the spinal cord that spreads rostrally segment by segment.

  • ASDA

    American Sleep Disorders Association

  • Aseptic meningitis

    Inflammation of the meninges not caused by culturable agents (bacteria, fungi).

  • Asn

    asparagine

  • asp

    aspartate

  • ASPA

    aspartoacylase

  • AST

    aspartate aminotransferase

  • Asterixis

    Lapses of maintained postures, considered a form of negative myoclonus.

  • Asymmetric tonic seizures

    Seizure with asymmetric posturing usually originating in the supplementary motor area.

  • Atactic

    Ataxic

  • Ataxia-telangiectasia

    An autosomal recessive condition that causes progressive incoordination, dilated blood vessels of skin and conjunctiva, frequent sinus and pulmonary infections, and an increased risk of certain malignancies.

  • Athetosis

    Writhing movements that blend continuously into a flowing stream of movement.

  • atonic seizure

    Epileptic attacks characterized by a sudden loss or diminution of muscle tone, which may be fragmentary or massive. Atonic seizures may be generalized or focal, but are usually seen in children with the Lennox-Gastaut syndrome. They must be differentiated from other seizure types that may cause sudden falls, such as myoclonic-astatic seizures, myoclonic seizures, and tonic seizures.

  • Atonic seizures

    Epileptic attacks characterized by a sudden loss or diminution of muscle tone, which may be fragmentary or massive. Atonic seizures may be generalized or focal, but are usually seen in children with the Lennox-Gastaut syndrome. They must be differentiated from other seizure types that may cause sudden falls, such as myoclonic-astatic seizures, myoclonic seizures, and tonic seizures.

  • ATP

    adenosine triphosphate (or adenosine triphosphatase)

  • ATP10C

    P-type ATPase encoding antiphospholipid translocase

  • Atrial fibrillation

    The state in which the normal rhythmical contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall, and the ventricles respond irregularly to the dysrhythmic bombardment from the atria.

  • Atypical Cogan syndrome

    Cogan syndrome presenting with ocular inflammation other than or in addition to interstitial keratitis, or with atypical audiovestibular symptoms.

  • Atypical Cogan's syndrome

    Cogan syndrome presenting with ocular inflammation other than or in addition to interstitial keratitis, or with atypical audiovestibular symptoms.

  • AUC

    area under the curve (concentration time)

  • Autonomic anxiety

    Gastrointestinal (eg, dry mouth, indigestion, diarrhea, cramps, belching), cardiovascular (eg, palpitations), respiratory (eg, hyperventilation, sighing), and other symptoms of anxiety (eg, headaches, urinary frequency, sweating).

  • autonomic symptom

    Signs and symptoms resulting from dysfunction in the parasympathetic and sympathetic nervous system.

  • Autonomic symptoms

    Signs and symptoms resulting from dysfunction in the parasympathetic and sympathetic nervous system.

  • Autosomal dominant nocturnal frontal lobe epilepsy

    Genetically inherited nocturnal seizure disorder associated with mutations in subunits of the nicotinic acetylcholine receptor.

  • AVM

    arteriovenous malformation

  • AVP

    arginine vasopressin

  • AVS

    antivasospasm substance((+/-)-N,N'-propylenedinicontinamide; nicaraven)

  • Axial system

    A means of stating different types of information in a systematic manner by listing on several "axes," to ensure that important information is not overlooked by the statement of a single major diagnosis. The International Classification of Sleep Disorders utilizes a three-axial system: Axes A, B, and C.

  • Axis A

    The first level of the International Classification of Sleep Disorders axial system on which the sleep disorder diagnoses, modifiers, and associated code numbers are stated.

  • Axis B

    The second level of the International Classification of Sleep Disorders axial system on which the sleep-related procedures and procedure features, and associated code numbers, are stated.

  • Axis C

    The third level of the International Classification of Sleep Disorders axial system on which ICD nonsleep diagnoses and associated code numbers are stated.

  • Axonal neuropathy

    Neuropathy due to axonal degeneration.

  • axonotmesis

    Injury to a peripheral nerve that produces complete interruption of the axon and myelin sheath while preserving the core connective tissue structure of the nerve.

  • AZQ

    aziridinylbenzoquinone

  • AZT

    azidothymidine (Zidovudine)

  • BACNS

    benign angiopathy of the central nervous system

  • BAER

    brainstem auditory evoked response

  • BAI1

    Brain-specific angiogenesis inhibitor

  • Balint syndrome

    Disorientation to place and difficulty in revisualizing locations. Patients also have a gaze apraxia. Patients see things piecemeal; they lack the ability to direct a panoramic view. They lack coordination of eye and hand motions. They cannot look directly at a position or object on which they have been instructed to focus.

  • Baller-Gerold syndrome

    A rare syndrome of craniosynostosis, radial aplasia, delayed psychomotor development, and variable craniofacial, cardiac, renal, and skeletal defects. Also known as Baller-Gerold syndrome.

  • Balo concentric sclerosis

    A rare demyelinating disease with lesions consisting of alternating bands of demyelinated and myelinated areas in concentric or lamellar configurations. It is felt to be a variant of multiple sclerosis or diffuse sclerosis, because transitional forms have been observed in both disorders.

  • Balo's concentric sclerosis

    A rare demyelinating disease with lesions consisting of alternating bands of demyelinated and myelinated areas in concentric or lamellar configurations. It is felt to be a variant of multiple sclerosis or diffuse sclerosis, because transitional forms have been observed in both disorders.

  • Basal ganglia

    Specific interconnected gray masses deep in the cerebral hemispheres and in the upper brainstem involved in multiple functions, specifically motor coordination.

  • Basilar impression

    distortion of the cranial base that occurs secondary to collapse of the occipital bones and secondary upward curvature of the foramen magnum and elevation of the floor of the posterior fossa.

  • Basilar invagination

    distortion of the cranial base that occurs secondary to collapse of the occipital bones and secondary upward curvature of the foramen magnum and elevation of the floor of the posterior fossa.

  • Basilar migraine

    Migraine with aura consisting of any two or more of the following symptoms: visual symptoms in both the temporal and nasal fields of both eyes, dysarthria, vertigo, tinnitus, decreased hearing, double vision, ataxia, bilateral paresthesias, bilateral paresis, and decreased level of consciousness.

  • basilar migraines

    Migraine with aura consisting of any two or more of the following symptoms: visual symptoms in both the temporal and nasal fields of both eyes, dysarthria, vertigo, tinnitus, decreased hearing, double vision, ataxia, bilateral paresthesias, and decreased level of consciousness.

  • BBB

    Blood-brain barrier

  • BCG

    Bacille Calmette-Guerin

  • BCNU

    1,3-bis(2-chloroethyl)-1-nitrosourea(carmustine)

  • BDI

    Beck Depression Index

  • BDNF

    brain-derived neurotrophic factor

  • Benign childhood epilepsy with centrotemporal spikes

    An idiopathic localization-related epilepsy characterized by childhood onset and centrotemporal spikes on EEG.

  • Benign paroxysmal vertigo of childhood

    Pediatric migraine equivalent characterized by sudden, brief attacks of vertigo.

  • Bereitschaftspotential

    Cortical premovement; potential precedes the movements.

  • Berry aneurysm

    A saccular aneurysm that is berry shaped

  • Beta activity

    A beta EEG wave or sequence of waves with a frequency of greater than 13 Hz.

  • Beta rhythm

    An EEG rhythm in the range of 13-35 Hz, when the predominant frequency, beta rhythm, is usually associated with alert wakefulness or vigilance and is accompanied by a high tonic EMG. The amplitude of beta rhythm is variable but usually is below 30 'V. This rhythm may be drug induced.

  • beta rhythms

    An EEG rhythm in the range of 13-35 Hz, when the predominant frequency, beta rhythm, is usually associated with alert wakefulness or vigilance and is accompanied by a high tonic EMG. The amplitude of beta rhythm is variable but usually is below 30 'V. This rhythm may be drug induced.

  • Beta-mannosidosis

    A very rare disorder of beta-mannosidase possibly localized to chromosome 4, resulting in lysosomal accumulation of mannodisaccharide in all tissues. Findings have included facial deformities, mental retardation, demyelinating peripheral neuropathy, recurrent infections, and onset from infancy to adulthood.

  • Beta-oxidation

    The usual pathway for degradation of fatty acids in which the chain is shortened by two carbons. Beta-oxidation occurs both in mitochondria and peroxisomes.

  • bFGF

    basic fibroblast growth factor

  • bi-PAP

    bilevel positive airway pressure

  • Bicoronal stenosis

    A condition in which the head is disproportionately wide. Brachycephaly can result from the premature fusion of the coronal sutures or from external deformation (most commonly prolonged lying on the back -- a positional deformity). The head flattens uniformly, causing a much wider and shorter head. Increased head height is also common in children with brachycephaly. Also known as brachycephaly.

  • BIFC

    benign infantile familial convulsions

  • Biochip

    The chip (GeneChipTM, Affymetrix Inc) is a piece of silica prepared through chemical and light processes to hold onto single strands of oligonucleotide probes. These can be bombarded with fluorescently tagged DNA or RNA from a patient or an organism, revealing genetic information.

  • biosynthesis

    Forming complex chemical compounds from simple substances in the body

  • Biotin holocarboxylase synthetase deficiency

    An inherited disorder of organic acidemia that is characterized by neurologic and cutaneous symptoms, ketolactic acidosis, and hyperammonemia.

  • Biotinidase deficiency

    An inherited disorder of organic acidemia that is characterized by neurologic and cutaneous symptoms, ketolactic acidosis, and hyperammonemia.

  • Blepharophimosis

    Condition in which the palpebral aperture is abnormally small.

  • Blepharoptosis

    Drooping of the upper eyelid.

  • Blepharospasm

    A focal dystonia of the eyelids resulting in involuntary eye closures that are disruptive and can cause functional blindness.

  • Blink reflex

    The electrical stimulation of the supraorbital nerve normally elicits two temporally separate responses of the orbicularis oculi.

  • Blink reflexes

    The electrical stimulation of the supraorbital nerve normally elicits two temporally separate responses of the orbicularis oculi.

  • BMAA

    B-N-methylamino-L-alanine

  • BNCT

    boron neutron capture therapy

  • Bobbing oscillopsia

    A form of oscillopsia occurring during ambulation and associated with vertical "bobbing" sensations of environmental movement, due to defective vertical vestibulo-ocular reflexes.

  • Bone conduction

    Transmission of sound to the cochlea through the skull.

  • BPE

    benign partial epilepsy

  • Brachycephalia

    A condition in which the head is disproportionately wide. Brachycephaly can result from the premature fusion of the coronal sutures or from external deformation (most commonly prolonged lying on the back -- a positional deformity). The head flattens uniformly, causing a much wider and shorter head. Increased head height is also common in children with brachycephaly. Also known as brachycephaly.

  • Brachycephaly

    A condition in which the head is disproportionately wide. Brachycephaly can result from the premature fusion of the coronal sutures or from external deformation (most commonly prolonged lying on the back -- a positional deformity). The head flattens uniformly, causing a much wider and shorter head. Increased head height is also common in children with brachycephaly. Also known as brachycephaly.

  • Bradykinesia

    Abnormal slowness of movement.

  • Bradyphrenia

    Slowness of thought processes.

  • Brain death

    Human death determined by demonstrating the permanent cessation of all clinical functions of the brain.

  • Breath-holding spell

    Episodes of apnea, cyanosis, and loss of consciousness in infants and toddlers, often related to a painful or upsetting stimulus.

  • Breath-holding spells

    Episodes of apnea, cyanosis, and loss of consciousness in infants and toddlers, often related to a painful or upsetting stimulus.

  • Brown-Sequard syndrome

    The neurologic picture produced by a transverse lesion of the right or left side of the spinal cord, including ipsilateral weakness and contralateral loss of superficial sensation.

  • BSAER

    brainstem auditory evoked response

  • BSCL2

    Berardinelli-Seip congenital lipodystrophy type 2

  • BTCG

    Brain Tumor Cooperative Group

  • BTSG

    Brain Tumor Study Group

  • BTX

    botulinum toxin

  • BUdR

    bromodeoxyuridine

  • C15orf2

    chromosome 15 open reading frame 2

  • CAA

    cerebral amyloid angiopathy

  • CABG

    coronary artery bypass graft.

  • CADASIL

    cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy.

  • Cadherins

    A family of cell-cell adhesion molecules that regulate morphogenesis in a variety of organs during development.

  • CAFS

    Conotruncal-anomaly-face syndrome

  • CAG

    cytosine adenosine guanine

  • California Verbal Auditory Learning Test

    A list of 10 items from a single category (eg, items on a shopping list) are repeated by the examiner on five trials. Patients must recall the list immediately after every trial to derive a learning curve, then again 10 to 15 minutes after the fifth trial then again 10 to 15 minutes after the fifth trial for a spontaneous delayed recall score. Intrusive errors are recorded as well as accurate responses. A list of the 10 original items along with 10 similar false responses is read aloud to the patient, who must correctly identify the 10 original items and suppress false positive responses.

  • Callosal

    Pertaining to the corpus callosum, the largest fiber bundle that links the two hemispheres.

  • Callosal apraxia

    Inpaired ability to pantomime to command, imitate, and use actual objects with the left hand, with spared ability to perform these tasks with the right hand.

  • Callosotomy

    Surgical division of the corpus callosum.

  • CAM

    cell adhesion molecule

  • Canalolithiasis

    Pathophysiological concept that explains benign paroxysmal positional vertigo by mobile particles within the semicircular canal, causing inappropriate endolymph flow after changes in head position.

  • CANOMAD

    chronic ataxic neuropathy with ophthalmoplegia, M-protein, agglutination and disialosyl antibodies

  • Canthus

    The angle formed at the nasal or temporal junction of the upper and lower eyelids.

  • Canthus (palpebral angle)

    The angle formed at the nasal or temporal junction of the upper and lower eyelids.

  • CAPD

    continuous ambulatory peritoneal dialysis

  • Capillary telangiectasia

    Occult lesions of no clinical significance. They consist of dilated endothelial-lined capillaries interspersed by normal neural tissue.

  • Capillary telangiectasias

    Occult lesions of no clinical significance. They consist of dilated endothelial-lined capillaries interspersed by normal neural tissue.

  • CAPIT

    A clinical assessment score for patients with Parkinson disease.

  • Carbamyl phosphate synthetase deficiency

    An autosomal recessive disorder of the urea cycle occurring in the mitochondrial matrix. Onset is seen between 24 and 72 hours of age with hyperammonemia, low citrulline levels, decreased orotic acid, hypotonia, vomiting, hyperventilation, and lethargy progressing to coma and seizures. Later and milder onset with partial deficiencies are also seen.

  • Carney complex

    A multiple neoplasia and lentiginosis syndrome characterized by myoxomas, mottled pigmentation, and endocrine dysfunction.

  • Carnitine

    A water-soluble quaternary amine.

  • Carotidynia

    Pain in the distribution of the carotid artery.

  • Carpenter syndrome

    A congenital syndrome characterized by oxycephaly and brachysyndactyly of the hands, polydactyly of the feet, and mental retardation. Also known as Carpenter syndrome.

  • Carpenter's syndrome

    A congenital syndrome characterized by oxycephaly and brachysyndactyly of the hands, polydactyly of the feet, and mental retardation. Also known as Carpenter syndrome.

  • Caseous necrosis

    A typical histopathological picture characterized by the presence of amorphous caseous mass, consisting mainly of degenerated cells, in the center of a granuloma.

  • CASPR2

    Contactin-associated protein 2

  • Catalepsy

    A condition of diminished responsiveness usually characterized by trancelike states and by a waxy rigidity of the muscles so that the patient tends to remain in any position in which he or she is placed.

  • Cataplexy

    A sudden decrement in muscle tone and loss of deep tendon reflexes leading to muscle weakness, paralysis, or postural collapse. Cataplexy usually is precipitated by an outburst of emotional expression--notably laughter, anger, or startle. One of the tetrad of symptoms of narcolepsy. During cataplexy, respiration and voluntary eye movements are not compromised.

  • Catastrophic epilepsy-induced encephalopathy

    Severe developmental disabilities affecting intellect, behavior, and mood as a consequence of frequent seizures during early childhood.

  • cauda equina

    Lesion of multiple lumbosacral roots in the region of the cauda equina, frequently resulting in sexual dysfunction and motor, reflex, and sensory deficits in the lower extremities, bladder, and bowel.

  • Cauda equina syndrome

    Lesion of multiple lumbosacral roots in the region of the cauda equina, frequently resulting in sexual dysfunction and motor, reflex, and sensory deficits in the lower extremities, bladder, and bowel.

  • Caudate nucleus

    An elongated, arched gray mass closely related to the lateral ventricle throughout its entire extent; together with the putamen, it forms the neostriatum.

  • causalgia

    A syndrome of sustained burning pain, allodynia, and hyperpathia after a traumatic nerve lesion, often combined with vasomotor and sudomotor dysfunction and later trophic changes.

  • Cavernous hemangioma

    Occult lesions that involve primarily veins, which usually remain clinically silent but may cause seizure, focal deficits, or hemorrhage. They consist of large sinusoidal vascular spaces densely clustered to form a compact mass which are surrounded by fibrous strands or septa and not normal neural tissue.

  • Cavernous hemangiomas

    Occult lesions that involve primarily veins, which usually remain clinically silent but may cause seizure, focal deficits, or hemorrhage. They consist of large sinusoidal vascular spaces densely clustered to form a compact mass which are surrounded by fibrous strands or septa and not normal neural tissue.

  • CAVH

    continuous arteriovenous hemofiltration

  • Cavum conchae

    A portion of the external ear forming the vestibule of the external auditory meatus.

  • Cavum velum interpositum

    Dilation of the velum interpositum that is the anterior extension of the subarachnoid space from the quadrigeminal plate cistern.

  • CBF

    cerebral blood flow

  • CBV

    cerebral blood volume

  • CCD

    central core disease

  • CCNU

    1-(2-chloroethyl)-3-cyclohexyl-1-nitorsourea (lomustine)

  • CCO

    cytochrome c oxidase

  • CCSVI

    chronic cerebrospinal venous insufficiency

  • CD4+ cell

    T-helper lymphocyte with CD4 antigen

  • CDC

    Centers for Disease Control and Prevention

  • CDG

    congenital disorders of glycosylation

  • CDGS

    carbohydrate deficient glycoprotein syndrome

  • cDNA

    complementary deoxyribonucleic acid

  • CDP

    cytidine 5'-diphosphate

  • CEA

    carcinoembryonic antigen

  • Cebocephaly

    Single-nostril nose; ocular hypotelorism.

  • Cecocentral scotoma

    Visual field defect that involves both fixation and the physiological blind spot.

  • cEEG

    continuous EEG

  • Central alexia

    Acquired reading disorder affecting the processes by which word forms activate meaning or speech production mechanisms.

  • Central core disease

    A disease that presents early in life as a floppy infant or later in life in the setting of mild progressive muscle weakness. The disease is characterized by musculo-skeletal and cardiac abnormalities and follows an autosomal dominant pattern of inheritance. Definitive diagnosis can only be made by muscle biopsy. Malignant hyperthermia susceptibility is associated with the disease.

  • Central herniation

    Caudal displacement of the cerebral hemisphere and basal nuclei by a supratentorial (usually frontal or parietal) mass lesion, resulting in compression and rostrocaudal translocation of the diencephalon and adjoining mesencephalon through the tentorial incisura.

  • Ceramide

    A long-chain lipid base made up of sphingosine, a C18 unsaturated hydrocarbon with an amide bond to a fatty acid chain at C-2.

  • Cerebellar hypoplasia

    A heterogeneous condition associated with other cerebral malformations, metabolic disorders, and degenerative diseases beginning in fetal life. It may be global or, less commonly, involves only the vermis; selective involvement of the lateral cerebellar hemisphere with preservation of the vermis also is described but is rare. Vermal hypoplasia may leave a gap in the cerebellar midline, as with the autosomal recessive Joubert syndrome, or may be absence of the vermis with fusion of the medial surfaces of the cerebellar hemispheres and dentate nuclei, a condition known as rhombencephalosynapsis. Global cerebellar hypoplasia sometimes occurs without other cerebral dysgeneses. The most constant clinical findings in infancy are gross motor developmental delay and generalized muscular hypotonia; inconstant findings include nystagmus, corticospinal tract deficits, mental retardation, and epilepsy. Cerebellar hypoplasia may result in histochemical changes in the muscle biopsy of fiber-type predominance or congenital muscle fiber-type disproportion, but necrotizing and dystrophic alterations are not found. CT scan can often confirm the diagnosis, but MRI with sagittal images demonstrates it best. The basis pontis also may be hypoplastic. Prognosis depends on underlying associated diseases, especially if progressive. Dysgeneses of the forebrain, including most of the primary disorders of neuroblast migration, may be associated CNS findings. Many genes are involved in this syndrome, and cerebellar hypoplasia is a feature in many chromosomal disorders.

  • Cerebellar hypoplasias

    A heterogeneous condition associated with other cerebral malformations, metabolic disorders, and degenerative diseases beginning in fetal life. It may be global or, less commonly, involves only the vermis; selective involvement of the lateral cerebellar hemisphere with preservation of the vermis also is described but is rare. Vermal hypoplasia may leave a gap in the cerebellar midline, as with the autosomal recessive Joubert syndrome, or may be absence of the vermis with fusion of the medial surfaces of the cerebellar hemispheres and dentate nuclei, a condition known as rhombencephalosynapsis. Global cerebellar hypoplasia sometimes occurs without other cerebral dysgeneses. The most constant clinical findings in infancy are gross motor developmental delay and generalized muscular hypotonia; inconstant findings include nystagmus, corticospinal tract deficits, mental retardation, and epilepsy. Cerebellar hypoplasia may result in histochemical changes in the muscle biopsy of fiber-type predominance or congenital muscle fiber-type disproportion, but necrotizing and dystrophic alterations are not found. CT scan can often confirm the diagnosis, but MRI with sagittal images demonstrates it best. The basis pontis also may be hypoplastic. Prognosis depends on underlying associated diseases, especially if progressive. Dysgeneses of the forebrain, including most of the primary disorders of neuroblast migration, may be associated CNS findings. Many genes are involved in this syndrome, and cerebellar hypoplasia is a feature in many chromosomal disorders.

  • Cerebral aneurysm

    Abnormal dilatation of an arterial vessel of the brain.

  • cerebral aneurysms

    Abnormal dilatation of an arterial vessel of the brain.

  • Cerebral sinovenous thrombosis

    Blood clot formation in a vein draining blood within the brain.

  • Cerebral vasospasm

    A reversible, exaggerated constriction of the cerebral vessels in response to perivascular blood in the subarachnoid space.

  • cerebral vasospasms

    A reversible, exaggerated constriction of the cerebral vessels in response to perivascular blood in the subarachnoid space.

  • Cerebral venous thrombosis

    Blood clot formation in a vein draining blood within the brain.

  • Cerebritis

    Focal suppurative infection of brain parenchyma occurring as an early event in development of brain abscess.

  • Cerebroside

    A ceramide with either glucose or galactose attached at C-1.

  • Cervical sprain

    A myofascial injury.

  • CESD

    cholesteryl ester storage disease

  • CGC

    cytosine-guanine-cytosine

  • CGG

    cytosine-guanine-guanine

  • CGRP

    calcitonin gene-related peptide

  • cGy

    centigray

  • CHADS2

    Congestive heart failure, Hypertention, Age, Diabetes, Stroke

  • Chancre

    Primary syphilitic skin lesion.

  • chancres

    Primary syphilitic skin lesion.

  • Cheiro-oral

    Relating to the hand and mouth.

  • Cherry-red spot

    Lipid accumulation in retinal ganglion cells

  • Cheyne-Stokes respiration

    A breathing pattern characterized by regular "crescendo-decrescendo" fluctuations in respiratory rate and tidal volume.

  • CHF

    congestive heart failure

  • Childhood-onset insomnia

    A life-long insomnia starting in early childhood that is not associated with psychiatric or organic factors.

  • Cholesteryl ester storage disease

    A somewhat milder disorder of defective activity of lysosomal acid lipase than is Wolman disease. It is characterized by hepatomegaly and hyperlipoproteinemia. Patients often survive to the second decade or later and may also benefit from enzyme replacement therapy.

  • Chotzen syndrome

    A condition in which there is coronal synostosis (unilateral or bilateral), facial asymmetry (particularly in individuals with unicoronal synostosis), ptosis, and characteristic appearance of the ear (small pinna with a prominent crus). Syndactyly of digits two and three of the hand is variably present. Also known as Saethre-Chotzen syndrome.

  • Chotzen's syndrome

    A condition in which there is coronal synostosis (unilateral or bilateral), facial asymmetry (particularly in individuals with unicoronal synostosis), ptosis, and characteristic appearance of the ear (small pinna with a prominent crus). Syndactyly of digits two and three of the hand is variably present. Also known as Saethre-Chotzen syndrome.

  • Chronic alcoholic myopathy

    Insidious muscle atrophy in chronic alcoholism.

  • Chronic inflammatory demyelinating polyradiculoneuropathy

    Acquired disorder of peripheral nerves, affecting motor and sensory fibers of the limbs, reaching the nadir of deficits 8 weeks or later from onset, and exhibiting a relapsing-remitting or progressive course. Diagnostic features include neurophysiologic evidence of demyelinating neuropathy, elevation of CSF protein level without pleocytosis, and neuropathologic findings of peripheral segmentary demyelination with perineural and endoneural inflammatory infiltrates. Pure motor or pure sensory variants are very rare and may represent an intermediate stage of the classic disease. Progressive chronic inflammatory demyelinating polyradiculoneuropathy is another variant, which shows a steadily worsening course without remission. Chronic inflammatory demyelinating polyradiculoneuropathy with severe axonal loss is a rare variant characterized by a relapsing-remitting course with evidence of axonal damage. Chronic inflammatory demyelinating polyradiculoneuropathy with monoclonal gammopathy of undetermined significance affects a subgroup of patients with the neuropathy and a monoclonal gammopathy usually of IgG or IgA type.

  • Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

    Acquired disorder of peripheral nerves, affecting motor and sensory fibers of the limbs, reaching the nadir of deficits 8 weeks or later from onset, and exhibiting a relapsing-remitting or progressive course. Diagnostic features include neurophysiologic evidence of demyelinating neuropathy, elevation of CSF protein level without pleocytosis, and neuropathologic findings of peripheral segmentary demyelination with perineural and endoneural inflammatory infiltrates. Pure motor or pure sensory variants are very rare and may represent an intermediate stage of the classic disease. Progressive chronic inflammatory demyelinating polyradiculoneuropathy is another variant, which shows a steadily worsening course without remission. Chronic inflammatory demyelinating polyradiculoneuropathy with severe axonal loss is a rare variant characterized by a relapsing-remitting course with evidence of axonal damage. Chronic inflammatory demyelinating polyradiculoneuropathy with monoclonal gammopathy of undetermined significance affects a subgroup of patients with the neuropathy and a monoclonal gammopathy usually of IgG or IgA type.

  • Chronic motor tic disorder

    Multiple motor (but not vocal) tics with a duration of at least 1 year.

  • Chronic or late whiplash syndrome

    Refers to persistent symptoms present more than 6 months after an accident.

  • Chronic single tic disorder

    Only 1 type of tic present with a duration of at least 1 year.

  • Chronic spinal epidural abscess

    Spinal epidural abscess presenting with a history over 4 weeks in length.

  • Chronic spinal epidural abscesses

    Spinal epidural abscess presenting with a history over 4 weeks in length.

  • Chronic subdural hematoma

    A hemorrhage that is not present on early imaging of the posttraumatic brain, but develops usually at least 21 weeks after the initial injury.

  • Chronic subdural hematomas

    A hemorrhage that is not present on early imaging of the posttraumatic brain, but develops usually at least 21 weeks after the initial injury.

  • Chronic vocal tic disorder

    Multiple vocal (but not motor) tics with a duration of at least 1 year.

  • Chronic whiplash syndrome

    Refers to persistent symptoms present more than 6 months after an accident.

  • Chronobiology

    The science relating to temporal, primarily rhythmical, processes in biology.

  • CIDP

    Acquired disorder of peripheral nerves, affecting motor and sensory fibers of the limbs, reaching the nadir of deficits 8 weeks or later from onset, and exhibiting a relapsing-remitting or progressive course. Diagnostic features include neurophysiologic evidence of demyelinating neuropathy, elevation of CSF protein level without pleocytosis, and neuropathologic findings of peripheral segmentary demyelination with perineural and endoneural inflammatory infiltrates. Pure motor or pure sensory variants are very rare and may represent an intermediate stage of the classic disease. Progressive chronic inflammatory demyelinating polyradiculoneuropathy is another variant, which shows a steadily worsening course without remission. Chronic inflammatory demyelinating polyradiculoneuropathy with severe axonal loss is a rare variant characterized by a relapsing-remitting course with evidence of axonal damage. Chronic inflammatory demyelinating polyradiculoneuropathy with monoclonal gammopathy of undetermined significance affects a subgroup of patients with the neuropathy and a monoclonal gammopathy usually of IgG or IgA type.

  • Circadian rhythm

    An innate daily fluctuation of physiological or behavioral functions, including sleep-wake states generally tied to the 24-hour daily dark-light cycle. Sometimes occurs at a measurably different periodicity (eg, 23 or 25 hours) when light-dark and other time cues are removed.

  • circadian rhythms

    An innate daily fluctuation of physiological or behavioral functions, including sleep-wake states generally tied to the 24-hour daily dark-light cycle. Sometimes occurs at a measurably different periodicity (eg, 23 or 25 hours) when light-dark and other time cues are removed.

  • Circasemidian rhythm

    A biological rhythm that has a period length of about half a day.

  • Circasemidian rhythms

    A biological rhythm that has a period length of about half a day.

  • Circumlocution

    Speech that is indirect, excessively wordy

  • CISS

    constructive interference in steady state

  • citric acid cycle

    Energy-producing cycle that takes place in the cell's mitochondria.

  • CJD178

    178 Asn Creutzfeldt-Jakob disease

  • CK

    creatine kinase

  • CK-MM

    creatine kinase MM band (isoenzyme of creatine kinase with muscle subunits)

  • clasp knife phenomenon

    Characterized by a free interval of movement of the limb, followed by a sudden stop and increase in muscle resistance that diminishes as the passive stretching of the limb continues.

  • Clasp-knife phenomenon

    Characterized by a free interval of movement of the limb, followed by a sudden stop and increase in muscle resistance that diminishes as the passive stretching of the limb continues.

  • CLN

    cervical lymph node

  • Cloning DNA

    Molecular cloning involves isolating a DNA sequence and obtaining multiple copies of it in an organism. Large quantities of DNA can then be isolated in pure form for analysis. Cloning a gene involves isolating a single gene or a part of a gene from the remainder of the genomic DNA. The cloned gene can then be produced in an unlimited amount.

  • closed head injuries

    Head injury without penetration of skull.

  • Closed head injury

    Head injury without penetration of skull.

  • Cloverleaf skull

    A congenital malformation in which the skull bones join to from three lobes. The condition may also be associated with hydrocephalus and facial and skeletal deformities. Also known as kleeblattsch.

  • Cloverleaf skull deformity

    A congenital malformation in which the skull bones join to from three lobes. The condition may also be associated with hydrocephalus and facial and skeletal deformities. Also known as kleeblattsch.

  • CMAP

    compound muscle action potential

  • CMAPs

    compound muscle action potentials

  • CMFTD

    congenital muscle fiber-type disproportion

  • CMRglu

    cerebral metabolic rate of glucose metabolism

  • CMS

    congenital myasthenic syndrome or syndromes

  • CMT

    Charcot-Marie-Tooth disease

  • CMV

    cytomegalovirus

  • CNS

    central nervous system

  • CNTF

    ciliary neurotrophic factor

  • CNV

    contingent negative variation

  • CoA

    coenzyme A

  • COD-MD

    cerebro-ocular dysplasia-muscular dystrophy

  • COHb

    carboxyhemoglobin

  • Coin test

    A test of ability to change sets. The examiner hides a coin in the left or right hand and changes its position according to patterns which change as the patient recognizes them. (eg, at the most elementary level, the examiner alternates regularly between hands. At the next level, he puts the coin in the hand opposite the one last chosen by the patient.)

  • COL6A1

    collagen VI A1 gene

  • COL6A2

    collagen VI A2 gene

  • COL6A3

    collagen VI A3 gene

  • Collateral inhibition

    Inhibition of a neuron by a branch ("collateral") off the axon of its neighbor. The axon itself projects a long distance, whereas the collateral branch synapses close to the cell body. The nervous system uses this principle extensively in two settings. Most commonly, collateral inhibition enhances contrast and sharpens a stimulus such as an image or sensation, by inhibiting neighboring neurons with similar function to the ones firing. Less frequently, collateral inhibition reduces the function of neurons with a role opposite to the ones firing, producing a positive feedback loop.

  • Color anomia

    Colors are recognized and matched but cannot be named.

  • COLQ

    collagen-like Q subunit

  • coma

    A state of complete unawareness of the environment; patients do not show any signs of awareness of themselves or of their environment; brainstem reflexes and posturing movements of the extremities are permissible, but eye opening should not occur in response to an external stimulus, and the patient should not move in a purposeful fashion.

  • Common whiplash

    A trauma causing cervical musculoligamental sprain or strain due to hyperextension-flexion, excluding fractures or dislocations of the cervical spine, head injury, or alteration of consciousness.

  • Communicating hydrocephalus

    Hydrocephalus despite unobstructed communication between the ventricles and subarachnoid space, eg, normal-pressure hydrocephalus secondary to meningitis.

  • Complementation analysis

    Analysis of gene defects by combining different mutations to restore the wild-type function.

  • Complicated X-linked spastic paraparesis

    Spastic paraparesis resulting from an L1 CAM gene mutation.

  • Compressive neuropathy

    Mononeuropathy due to focal compression.

  • COMS

    cerebro-oculo-muscular syndrome

  • COMT

    catechol-ortho-methyl-transferase

  • Conceptual apraxia

    Loss of knowledge base needed to select and use the appropriate tool for a given context. These patients will make semantic or conceptual errors such as content and tool selection errors when asked to pantomime to command.

  • Conditioned insomnia

    An insomnia that is produced by the development, during an earlier experience of sleeplessness, of conditioned arousal. Causes of the conditioned stimulus can include the customary sleep environment or thoughts of disturbed sleep. A conditioned insomnia is one component of psychophysiological insomnia.

  • Conduct disorder

    Persistent and repetitive pattern of behavior that violates societal norms or the rights of others.

  • Conduct disorders

    Persistent and repetitive pattern of behavior that violates societal norms or the rights of others.

  • Conduction apraxia

    Impaired ability to imitate gesture relative to pantomime to command.

  • Condyloma lata

    Perineal or perianal skin lesions.

  • Confabulation

    Involuntarily erroneous recall of autobiographical events, often associated with memory disorder

  • Congenital infection

    Infection of a fetus with a pathogenic organism.

  • Conradi-Hünermann syndrome

    A rare genetic X-linked dominant disorder classified as a form of chondrodysplasia punctata and characterized by skeletal defects, skin changes, cataracts, and short stature

  • Conspecific

    From the same species as another organism

  • Constant routine

    A chronobiological test of the endogenous pacemaker that involves a 36-hour baseline monitoring period, followed by a 40-hour waking episode of monitoring with the individual on a constant routine of food intake, position, activity, and light exposure.

  • Constructional apraxia

    Inability to copy object drawings. Patients often omit the left-side constituents in size and angles, as is seen with right posterior parietal lobe lesions.

  • Contracture

    Limitation of range of motion, usually at a joint or in a limb.

  • Contralesional

    Opposite the side of brain injury

  • Convexity subdural empyema

    A subdural empyema lying over the cerebral convexity

  • COPD

    chronic obstructive pulmonary disease

  • CoQ

    Coenzyme Q

  • CoQ10

    Coenzyme Q10

  • Core Assessment Program for Intracerebral Transplantation

    A clinical assessment score for patients with Parkinson disease.

  • Core Assessment Program for Intracerebral Transplantation (CAPIT)

    A clinical assessment score for patients with Parkinson disease.

  • Coronal synostosis

    The coronal suture closes early and restricts growth of the forehead on the "synostosed" side. This leads to a flattening of the forehead and a "compensatory" bulging of the forehead on the opposite side. Also known as plagiocephaly.

  • Corpus callosum

    An arched mass of white matter in the depths of the longitudinal fissure, composed of transverse fibers connecting the cerebral hemispheres.

  • Corpus striatum

    A subcortical mass of gray and white substance in front of and lateral to the thalamus in each cerebral hemisphere.

  • Cortical dysplasia

    A spectrum of derangements in the development of the cerebral cortex that cause epilepsy in infants and children. It is associated with a range of morphologic features and with multiple putative etiologic factors including genetic and environmental influences. Cortical dysplasia is best evaluated microscopically, and can be characterized with regard to nine specific and easily identifiable microscopic abnormalities that may be present: (1) cortical laminar disorganization, (2) neurons in the neocortical molecular layer, (3) single heterotopic white matter neurons, (4) persistent remnants of the subpial granule cell layer, (5) marginal glioneuronal heterotopia, (6) neuronal heterotopia, (7) polymicrogyria, (8) neuronal cytomegaly with cytoskeletal abnormalities, and (9) balloon cells.

  • Cortical dysplasias

    A spectrum of derangements in the development of the cerebral cortex that cause epilepsy in infants and children. It is associated with a range of morphologic features and with multiple putative etiologic factors including genetic and environmental influences. Cortical dysplasia is best evaluated microscopically, and can be characterized with regard to nine specific and easily identifiable microscopic abnormalities that may be present: (1) cortical laminar disorganization, (2) neurons in the neocortical molecular layer, (3) single heterotopic white matter neurons, (4) persistent remnants of the subpial granule cell layer, (5) marginal glioneuronal heterotopia, (6) neuronal heterotopia, (7) polymicrogyria, (8) neuronal cytomegaly with cytoskeletal abnormalities, and (9) balloon cells.

  • Cortical reflex myoclonus

    Involuntary myoclonic jerking induced by passive or voluntary movement of the involved body part, associated with focal contralateral sensorimotor cortical electrical discharge, following cerebral hemispheric injury.

  • Cowdry types A and B

    Cowdry A are intranuclear inclusion bodies; Cowdry B are cytoplasmic inclusion bodies.

  • Cowdry types A and B inclusion bodies

    Cowdry A are intranuclear inclusion bodies; Cowdry B are cytoplasmic inclusion bodies.

  • COX

    cytochrome c oxidase

  • CPA

    cerebellopontine angle

  • CPAP

    continuous positive airway pressure

  • CPH

    chronic paroxysmal hemicrania

  • CPP

    cerebral perfusion pressure

  • CPS

    carbamyl phosphate synthetase

  • CPT

    carnitine palmitoyltransferase

  • CPT-I

    carnitine palmitoyltransferase I

  • CPT-II

    carnitine palmitoyltransferase II

  • CR

    complete response

  • Crack cocaine

    Alkaloidal cocaine.

  • Cranial meningocele

    A cephalocele containing only meninges.

  • Cranial meningoceles

    A cephalocele containing only meninges.

  • Craniofacial dysostosis

    An inherited cranial deformity characterized by widening of the skull and high forehead, abnormal width between and protrusion of the eyes, a beaked nose, and hypoplasia of the maxilla. Also called Crouzon syndrome.

  • Craniosynostosis-radial aplasia syndrome

    A rare syndrome of craniosynostosis, radial aplasia, delayed psychomotor development, and variable craniofacial, cardiac, renal, and skeletal defects. Also known as Baller-Gerold syndrome.

  • CRASH syndrome

    Syndrome of corpus callosum hypoplasia, retardation, adducted thumbs, spastic paraplegia, and hydrocephalus.

  • Cretinism

    Developmental abnormalities resulting from congenital hypothyroidism.

  • CRM

    cross-reacting material

  • Crossed aphasia

    Aphasia following right hemisphere injury in a right-handed person, suggesting a premorbidly atypical brain organization for language.

  • Crouzon syndrome

    An inherited cranial deformity characterized by widening of the skull and high forehead, abnormal width between and protrusion of the eyes, a beaked nose, and hypoplasia of the maxilla. Also called Crouzon syndrome.

  • Crouzon's syndrome

    An inherited cranial deformity characterized by widening of the skull and high forehead, abnormal width between and protrusion of the eyes, a beaked nose, and hypoplasia of the maxilla. Also called Crouzon syndrome.

  • CRP

    C-reactive protein

  • CRS

    congenital rubella syndrome

  • CS-A

    Cockayne syndrome complementation group A

  • CS-B

    Cockayne syndrome complementation group B

  • CSF

    cerebrospinal fluid

  • CSWSS

    continuous spikes and waves during slow sleep syndrome

  • CT

    computed tomography

  • CTA

    computed tomography angiography

  • CTG

    cytosine-thymidine-guanine

  • CTX

    cerebrotendinous xanthomatosis

  • Cuban optic neuropathy

    An optic neuropathy with many toxic/nutritional factors but principally exposure to methanol and folic acid deficiency.

  • Cupulolithiasis

    Pathophysiological concept that explains benign paroxysmal postioning vertigo by particles attached to the cupula, rendering it sensitive to gravity.

  • Cx32

    connexin 32

  • Cyclic alternating pattern

    This is a normal phenomenon of NREM sleep. Periods of EEG activation briefly interrupt periods of sleep quiescence.

  • Cyclopia

    Single midline orbit.

  • cys

    cysteine

  • Cystathionine beta-synthase

    A vitamin B-6-dependent enzyme that catalyzes the transsulfuration of homocysteine. Homozygous deficiency of cystathionine beta-synthase is the most common cause of severe hyperhomocysteinemia.

  • cytokine

    Products secreted by cells of the immune system.

  • Cytokines

    Products secreted by cells of the immune system.

  • CZ

    central zed (midline)

  • D-2 hydroxyglutaric aciduria

    Very rare disease of unknown etiology with early-onset developmental delay, seizures/hypsarrhythmia, and possibly weakness. D-2-hydroxyglutaric acid excretion is increased in urine.

  • d4T

    stavudine

  • DAF

    down-gaze paralysis, ataxia, foam cells

  • DAG

    dystrophin-associated glycoprotein

  • DAI

    diffuse axonal injury

  • DAVF

    dural arteriovenous fistula

  • DAVM

    dural arteriovenous malformation

  • DBH

    dopamine-beta-hydroxylase

  • DCS

    dorsal column stimulation

  • DDAVP

    desmopressin

  • ddC

    dideoxycytidine

  • ddI

    dideoxyinosine

  • DDS

    dialysis disequilibrium syndrome

  • declarative memory

    Long-term memory is often divided into two main types: explicit (or declarative) memory and implicit (or procedural) memory. Declarative is memory of facts and events, and refers to those memories that can be consciously recalled (or "declared"). It is sometimes called explicit memory because it consists of information that is explicitly stored and retrieved, although it is more properly a subset of explicit memory. Declarative memory can be further sub-divided into episodic memory and semantic memory.

  • Declarative memory

    Memory processes that operate under conscious awareness, including intentional learning and willful recall; factual memory.

  • Decompression sickness

    Clinical symptoms and physical signs caused by a rapid reduction of the environmental pressure.

  • DEE

    developmental and epileptic encephalopathy

  • Defective interfering particle

    Virions containing only a portion of the complete viral genome, which compete with the wild-type virus for replication, a mechanism of viral persistence.

  • Defective interfering particles

    Virions containing only a portion of the complete viral genome, which compete with the wild-type virus for replication, a mechanism of viral persistence.

  • deformation

    Distortion by a physical force of an otherwise normal structure.

  • Delayed sleep phase

    A condition that occurs when the clock hour at which sleep normally occurs is moved back in time within a given 24-hour sleep-wake cycle. This results in a temporarily displaced, that is delayed, occurrence of sleep within the 24-hour cycle. The same term denotes a circadian rhythm sleep disturbance, called the delayed sleep phase syndrome.

  • Delayed traumatic intracerebral hematoma

    A hemorrhage that is not present on early imaging of the posttraumatic brain, but develops usually at least 6 hours after the initial injury.

  • Delayed traumatic intracerebral hematomas

    A hemorrhage that is not present on early imaging of the posttraumatic brain, but develops usually at least 6 hours after the initial injury.

  • Delirium

    A state of waxing and waning consciousness, with prominent disorientation, fear, hallucinations, as well as an altered sleep/wake cycle.

  • Delirium cordis

    Synonymous with atrial fibrillation, the state in which the normal rhythmical contractions of the cardiac atria are replaced by rapid irregular twitchings of the muscular wall, and the ventricles respond irregularly to the dysrhythmic bombardment from the atria.

  • Delirium tremen

    Acute delirium or encephalopathy seen during alcohol withdrawal.

  • Delirium tremens

    Acute delirium or encephalopathy seen during alcohol withdrawal.

  • Delta activity

    EEG activity with a frequency of less than 4 Hz (usually 0.1-3.5 Hz). In human sleep scoring, the minimum characteristics for scoring delta waves is conventionally 75 'V (peak-to-peak) amplitude, and 0.5-second duration (2 Hz) or less.

  • Delta sleep stage

    Indicative of the stage of sleep in which EEG delta waves are prevalent or predominant (sleep stages 3 and 4, respectively). See Slow Wave Sleep.

  • Demyelinating neuropathies

    Neuropathy resulting from damage to the myelin sheath of peripheral nerves.

  • Demyelinating neuropathy

    Neuropathy resulting from damage to the myelin sheath of peripheral nerves.

  • Dense core vesicle

    Electron-dense spherical inclusions seen in the axon and axon hillock of ganglion cells.

  • Dense core vesicles

    Electron-dense spherical inclusions seen in the axon and axon hillock of ganglion cells.

  • Deoxyribonucleic acid microarray

    This rapid method of sequencing and analyzing genes uses microchip technology based on miniaturization, integration, and parallel-processing techniques from the computer industry. DNA microchips are also used for the diagnosis of diseases and genetic screening.

  • Deoxyribonucleic acid microarrays

    This rapid method of sequencing and analyzing genes uses microchip technology based on miniaturization, integration, and parallel-processing techniques from the computer industry. DNA microchips are also used for the diagnosis of diseases and genetic screening.

  • Depersonalization

    Detachment from feeling responsible for or in control of one's own behavior.

  • Descending myelopathy

    A disease causing necrosis of the spinal cord that spreads caudally segment by segment.

  • Desmin body myofibrillar myopathies

    A rare chronic noninflammatory, sporadic or inherited myopathy with or without a cardiomyopathy characterized by inclusions immunoreactive to desmin in skeletal and/or cardiac muscle. The myopathy is usually proximal, but combined proximal and distal features occur and the distal myopathy can predominate. Electron microscopy shows granulofilamentous inclusions in various arrangements.

  • Desmin body myofibrillar myopathy

    A rare chronic noninflammatory, sporadic or inherited myopathy with or without a cardiomyopathy characterized by inclusions immunoreactive to desmin in skeletal and/or cardiac muscle. The myopathy is usually proximal, but combined proximal and distal features occur and the distal myopathy can predominate. Electron microscopy shows granulofilamentous inclusions in various arrangements.

  • Desmin storage

    Intrasarcoplasmic deposition of electron-dense granulofilamentous material, or bundles of filaments 8 to 10 nm thick, revealed by immunostaining with monoclonal antidesmin antibodies.

  • Desmoplasia

    Hyperplasia of fibroblasts and disproportionate formation of fibrous connective tissue, especially in the stroma of a malignant tumor.

  • Detrusor muscle

    The muscle of the bladder wall that is responsible for emptying the bladder. It contracts with muscarinic, parasympathetic stimulation, using acetylcholine as a neuromuscular transmitter.

  • Detrusor-sphincter dyssynergia

    Failure of the external sphincter of the bladder to relax when the detrusor muscle contracts.

  • Developmental dyslexia

    Specific difficulty in learning to read despite conventional instruction, adequate intelligence, and sociocultural opportunity.

  • Developmental language disorder

    A childhood condition of abnormal communication that causes delays in normal expressive or receptive language.

  • DFMO

    difluoromethylornithine

  • DFR

    dynamic reference frame

  • DG/VCF

    DiGeorge/Velocardiofacial syndrome

  • DGS

    DiGeorge syndrome

  • DHCA

    dihydroxycholestanoic acid

  • DHE

    dihydroergotamine

  • DHPG

    3,4 dihydroxyphenylglycol

  • Diabetic amyotrophy

    A subacute, asymmetric, proximal, painful motor neuropathy resulting from diabetes mellitus.

  • Diabetic neuropathy

    A distal symmetrical, predominantly sensory neuropathy resulting from diabetes mellitus.

  • Diastase-resistant

    Inability to break a substance down into simple sugars using a mixture of malt-derived enzymes.

  • DIDMOAD

    diabetes insipidus, diabetes mellitus, optic atrophy, and sensorineural deafness

  • Differential display of mRNA

    A powerful, rapid, and sensitive adjunct or alternative to traditional subtractive hybridization techniques. It enables a two-dimensional side-by-side comparison of gene sequences expressed in different cells, and does not require prior gene sequence info

  • Diffuse sclerosis

    A very rare disorder that affects chiefly children over the age of 7, characterized by large subacute or chronic myelinoclastic lesions, usually bilateral, in the centrum semiovale.

  • Dihydropteridine reductase deficiency

    A widely variant autosomal recessive disorder of tetrahydrobiopterin metabolism resulting in reduced synthesis of biogenic amine neurotransmitters. Microcephaly, progressive neurologic deterioration, developmental delay, and convulsions are common. Variant forms have been described in which the neurologic signs are either minor or absent. The urine pterin pattern is similar to that seen in patients with hyperphenylalaninemia due to phenylalanine hydroxylase deficiency; therefore, definitive differential diagnosis can only be made by direct measurement of dihydropteridine reductase activity in blood or from blood on Guthrie cards. The tetrahydrobiopterin loading test is not always positive. Several mutations for both typical and atypical forms have been described.

  • DILS

    diffuse infiltrative lymphocytosis syndrome

  • DIMS

    disorders of initiating and maintaining sleep

  • Diplacusis

    Perception of the same sound with different pitches in the normal and affected ear.

  • Disk pseudoedema

    Elevation of the optic disk, which does not leak when studied with fluorescein angiography.

  • Disomy

    Uniparental disomy is the inheritance of two copies of a particular chromosome from one parent and none from the other. Isodisomy occurs when there are two copies of exactly the same chromosome from each parent, and heterodisomy when there are two different copies of a chromosome pair from the same parent.

  • Dissociation apraxia

    Inability to pantomime to command, with spared ability to imitate gestures and manipulate objects in the environment. Other modality differences such as inability to pantomime as well as difficulty imitating gestures and using real tools may be included.

  • Dissociative seizures

    Involuntary intermittent events that resemble epileptic seizures but are psychologically induced.

  • Distal sensorimotor polyneuropathy

    Motor neuropathy that involves distal sensory and motor nerves symmetrically.

  • Diurnal

    Pertaining to the daytime.

  • DKA

    diabetic ketoacidosis

  • DLRPN

    diabetic lumbosacral radiculoplexus neuropathy

  • DM1

    dystrophia myotonica I

  • DM2

    dystrophia myotonica II

  • DMD

    Duchenne muscular dystrophy

  • DMRV

    distal myopathy with rimmed vacuoles

  • DNA

    deoxyribonucleic acid

  • DNA microarray

    This rapid method of sequencing and analyzing genes uses microchip technology based on miniaturization, integration, and parallel-processing techniques from the computer industry. DNA microchips are also used for the diagnosis of diseases and genetic screening.

  • DNA microarrays

    This rapid method of sequencing and analyzing genes uses microchip technology based on miniaturization, integration, and parallel-processing techniques from the computer industry. DNA microchips are also used for the diagnosis of diseases and genetic screening.

  • DNA polymerase

    The enzymes that assemble the polymer from deoxyribonucleotides in the triphosphate form during DNA replication. Breakdown of the triphosphate group releases a great deal of energy which drives DNA polymerization.

  • Dolichoectasia

    Dilatation and tortuosity

  • DOPAC

    dopamine, 3,4-dihydroxyphenylacetic acid

  • Dopamine beta-hydroxylase deficiency

    An autosomal recessive disorder resulting in severe autonomic and noradrenergic dysfunction, stemming from inability to convert dopamine to norepinephrine. Symptoms are usually diagnosed in adulthood, although ptosis, hypothermia, severe orthostatic hypotension, hypoglycemia, and other autonomic abnormalities may have been evident since birth. Testing reveals extremely low levels of norepinephrine, epinephrine, and their metabolites in plasma, CSF, and urine.

  • DPME

    diffuse pachymeningeal enhancement

  • DPT

    diphtheria-pertussis-tetanus

  • Dravet syndrome

    Epileptic syndrome of genetic origin characterized by infantile onset, multiple seizure types, and progressive cognitive decline.

  • Dravet's syndrome

    Epileptic syndrome of genetic origin characterized by infantile onset, multiple seizure types, and progressive cognitive decline.

  • DREZ

    dorsal root entry zone

  • DS

    dermatan sulfate

  • DSA

    digital subtraction angiography

  • dsDNA

    double-stranded deoxyribonucleic acid

  • DSM

    Diagnostic and Statistical Manual of Mental Disorders

  • DSM-4

    diagnostic and statistical manual of mental disorders.

  • DSM-IV

    Diagnostic and Statistical Manual of Mental Disorders, 4th edition

  • DSPD

    delayed sleep phase disorder

  • DST

    dexamethasone suppression test

  • DTBZ

    dihydrotetrabenazine

  • DTI

    diffusion tensor imaging

  • DTIC

    dacarbazine

  • DTICH

    delayed traumatic intracerebral hematoma

  • DTPA

    Diethylenetriamine pentaacetic acid

  • Dura

    The outermost layer of the cranial meninges.

  • Dural sinus thrombosis

    Blood clot formation in a vein draining blood within the brain.

  • Duration criteria

    Criteria established in the International Classification of Sleep Disorders for determining the duration of a particular disorder as acute, subacute, or chronic.

  • DWI

    Diffusion-weighted imaging

  • DXA

    Dual energy x-ray absorptiometry

  • Dynamic aphasia

    Difficulty in organizing and planning language expression. Reduced spontaneous language, good comprehension, and good repetition are found.

  • Dysarthria

    Disturbance of articulation of speech.

  • Dysautonomic crisis

    A constellation of signs resembling a central sympathetic storm. Nausea or vomiting is a consistent feature. In addition, there is hypertension, tachycardia, diffuse sweating, erythematous skin blotching, and even personality change.

  • Dysembryoplastic neuroepithelial tumor

    An indolent glioneural neoplasm of the temporal or frontal lobes that produces medically refreactory partial epilepsy.

  • Dysesthesia

    Impairment of any sense, especially of the sense of touch; an unpleasant abnormal sensation produced by normal stimuli.

  • Dyslexia

    A partial deficit in reading. Colloquial usage has transformed it into a term used to describe the inability to acquire reading proficiency, with onset in childhood.

  • Dysostosis multiplex

    Widespread skeletal deformities seen in mucopolysaccharidoses, particularly Hurler disease. Includes poorly formed pelvis with small femoral heads and coxa valga; short, thickened, irregular clavicles; oar-shaped ribs; shortened, trapezoidal phalanges; enlarged diaphyses of long bones with irregular appearance of the metaphyses; underdeveloped epiphyseal centers; anterior hypoplasia of lumbar vertebrae with kyphosis; large skull with thickened calvarium; premature closure of the lambdoid and sagittal sutures; shallow orbits; enlarged J-shaped sella; odontoid hypoplasia.

  • Dysphagia

    Difficulty with normal swallowing.

  • Dysplasia

    Abnormal tissue development.abnormal cellular organization within a tissue resulting in structural changes—for example, within cartilage and bone in skeletal dysplasias.

  • Dysprosodic

    Pertaining to abnormal speech intonation.

  • Dyssomnia

    A primary disorder of initiating and maintaining sleep or of excessive sleepiness. The dyssomnias are disorders of sleep or wakefulness per se; not a parasomnia.

  • Dystonia

    An involuntary movement disorder characterized by abnormal twisting, tremor, or posturing of a body part. Dystonias can be focal (involving a single body part), segmental (involving adjacent body parts), or generalized. Dystonias are most frequently idiopathic, but can occur secondary to neuroleptic use (tardive dystonia), structural lesions in the brain or spinal cord, or head trauma. Dystonias can also be a part of one of many inherited neurologic syndromes, such as Wilson disease, or occur in patients with Parkinson disease. Treatments for the various dystonias include trials of oral medications (such as anticholinergics, benzodiazepines, and baclofen) as well as botulinum toxin and deep brain stimulation.

  • Dystonia

    An involuntary movement disorder characterized by abnormal twisting, tremor, or posturing of a body part. Dystonias can be focal (involving a single body part), segmental (involving adjacent body parts), or generalized. Dystonias are most frequently idiopathic, but can occur secondary to neuroleptic use (tardive dystonia), structural lesions in the brain or spinal cord, or head trauma. Dystonias can also be a part of one of many inherited neurologic syndromes, such as Wilson disease, or occur in patients with Parkinson disease, often as a sign of dopaminergic overdosing. Treatments include trials of oral medications (such as anticholinergics, benzodiazepines, and baclofen) as well as some surgical approaches (such as selective denervation for torticollis and myectomy for blepharospasm).

  • Early congenital syphilis

    Congenital syphilis clinically manifested before 2 years of age.

  • Early myoclonic encephalopathy

    A disease that presents in early infancy and is marked by erratic, fragmentary myoclonus, developmental delay, and early death.

  • early posttraumatic seizure

    Seizures occurring while the patient is still suffering from the direct effects of the head injury, a period commonly defined as 1 week after head injury.

  • Early posttraumatic seizures

    Seizures occurring while the patient is still suffering from the direct effects of the head injury, a period commonly defined as 1 week after head injury.

  • ECBT

    emotion-focused cognitive behavioral therapy

  • ECG

    electrocardiography

  • Echolalia

    Speech limited to repetition of what is heard or perseveration on the last few words heard.

  • ECLS

    extracorporeal life support

  • ECMO

    extracorporeal membrane oxygenation

  • ECoG

    electrocorticography

  • Ectropion

    Lower eyelid flaccidity.

  • EDAS

    encephalo-duro-angio-synangiosis

  • EDMD

    Emery-Dreifuss muscular dystrophy

  • EDSS

    Expanded Disability Status Scale

  • EDTA

    ethylenediaminetetraacetic acid

  • EEG

    electroencephalography

  • EGF

    epidermal growth factor

  • EGFR

    epidermal growth factor receptor

  • EGPA

    eosinophilic granulomatosis with polyangiitis

  • EGR-2

    early growth response gene-2

  • Eisenmenger syndrome

    The late development of pulmonary hypertension and right ventricular hypertrophy leading to the reversal of the preexisting shunt from left-to-right to right-to-left. Clinically characterized by a tetrad of an underlying heart defect that allows initial shunting of blood from the left side of the heart to the right; the development of pulmonary hypertension; polycythemia; the subsequent reversal of the shunt.

  • Eisenmenger's syndrome

    The late development of pulmonary hypertension and right ventricular hypertrophy leading to the reversal of the preexisting shunt from left-to-right to right-to-left. Clinically characterized by a tetrad of an underlying heart defect that allows initial shunting of blood from the left side of the heart to the right; the development of pulmonary hypertension; polycythemia; the subsequent reversal of the shunt.

  • EKG

    electrocardiography

  • Elaborative processing

    Learning under conditions where the to-be-learned materials are manipulated, as in making associations to the words (ie, "is it a pleasant word?" or making a sentence using the word).

  • ELAM-1

    endothelial leukocyte adhesion molecule-1

  • Electro-oculogram

    A recording of voltage changes resulting from shifts in position of the ocular globes, as each globe is a positive (anterior) and negative (posterior) dipole; along with the EEG and the EMG, one of the three basic variables used to score sleep stages and waking. Sleep recording in humans utilizes surface electrodes placed near the eyes to record the movement (incidence, direction, and velocity) of the eyeballs, Rapid eye movements in sleep form one part of the characteristics of the REM sleep state.

  • Electro-oculogram (EOG)

    A recording of voltage changes resulting from shifts in position of the ocular globes, as each globe is a positive (anterior) and negative (posterior) dipole; along with the EEG and the EMG, one of the three basic variables used to score sleep stages and waking. Sleep recording in humans utilizes surface electrodes placed near the eyes to record the movement (incidence, direction, and velocity) of the eyeballs, Rapid eye movements in sleep form one part of the characteristics of the REM sleep state.

  • Electroconvulsive therapy

    Inducing convulsions by means of electricity; used in the treatment of certain psychiatric disorders, including refractory depression.

  • Electronystagmogram

    Electrical test that quantitatively measures eye movements in response to stimulation of vestibular structures. It is used in elucidating the cause of vertigo, ie, peripheral versus central.

  • ELISA

    enzyme-linked immunoabsorbent assay

  • EMA

    eyelid myoclonia with absences

  • emboli

    Obstruction or occlusion of a vessel by a plug composed of a detached thrombus, vegetation, mass of bacteria, or other foreign body.

  • Embolism

    Obstruction or occlusion of a vessel by a plug composed of a detached thrombus, vegetation, mass of bacteria, or other foreign body.

  • EMG

    electromyography

  • EMS

    emergency management of stroke

  • Encephalitis

    Inflammatory disease of the brain.

  • Encephalocele

    A cephalocele containing both meninges and brain tissue.

  • Encephalocystocele ((meningoencephalocele)

    A cephalocele containing meninges, brain tissue, and part of the ventricle.

  • Encephalomyelitis

    Inflammatory disease of the brain and spinal cord.

  • End-tidal carbon dioxide

    Carbon dioxide value usually determined at the nares by an infrared carbon dioxide gas analyzer. The value reflects the alveolar or pulmonary arterial blood carbon dioxide level.

  • End-tidal CO2

    Carbon dioxide value usually determined at the nares by an infrared carbon dioxide gas analyzer. The value reflects the alveolar or pulmonary arterial blood carbon dioxide level.

  • Endarterectomy

    A surgical procedure that strips the inner lining of an artery generally to remove atherosclerotic plaque.

  • Endovascular technique

    A method in which a catheter passed from within the vessel is used for treatment.

  • ENS

    epidural nevus syndrome

  • Enthesitis

    Inflammation of tendonous or muscular attachment to bone.

  • Entrainment

    Synchronization of a biological rhythm by a forcing stimulus such as an environmental time cue (Zeitgeber). During entrainment, the frequencies of the two cycles are the same or are integral multiples of each other.

  • Enzyme inducer

    A drug that increases synthesis of drug-metabolizing enzymes.

  • EOG

    A recording of voltage changes resulting from shifts in position of the ocular globes, as each globe is a positive (anterior) and negative (posterior) dipole; along with the EEG and the EMG, one of the three basic variables used to score sleep stages and waking. Sleep recording in humans utilizes surface electrodes placed near the eyes to record the movement (incidence, direction, and velocity) of the eyeballs, Rapid eye movements in sleep form one part of the characteristics of the REM sleep state.

  • EORTC

    European Organization for Research on Treatment of Cancer

  • Eosinophilic polymyositis

    An inflammatory disease of skeletal muscle that is characterized by an eosinophilic infiltration of muscle perimysium or endomysium, without evidence of a parasitic infection.

  • EPC

    epilepsia partialis continua

  • Ephapse

    A false synapse at which ectopic activity may be triggered by mechanical irritation, changes in regional electrolyte concentration, or flow of extracellular current during passage of nerve impulses in adjacent fibers.

  • Ephaptic transmission

    Activation of an axon by "cross-talk" from a neighboring axon. Axons are normally shielded by their Schwann cells and by a purposely short length of contiguity between any two fibers. The nerve sprouts that follow a nerve injury have neither of these properties.

  • Epidermal nevus syndrome

    A neurocutaneous disease involving a variety of cutaneous nevi but also including verrucous lesions, sebaceous and hair follicle involvement, and pigmentary changes on the face and scalp primarily, but also involving the trunk and extremities.

  • Epidural

    Location outside and adjacent to the dura.

  • Epilepsia partialis continua

    A particular form of partial status epilepticus characterized by continuous focal clonic motor seizures.

  • Epilepsy with myoclonic-atonic seizures

    Infantile-onset epilepsy associated with psychomotor retardation and multiple seizure types, but most prominently myoclonic and atonic seizures.

  • Episodic memory

    Learning and recall of facts and events.

  • Epoch

    A measure of duration of the sleep recording that typically is 20 or 30 seconds in duration, depending on the paper speed of the polysomnograph, and corresponds to one page of the polysomnogram.

  • EPP

    endplate potential

  • EPPS

    endplate potntials

  • ERG

    electroretinography or electroretinogram

  • ERP

    event-related potentials

  • ERPs

    event-related potentials

  • ESR

    erythrocyte sedimentation rate

  • ESRD

    end-stage renal disease

  • Essential myoclonus

    Monosymptomatic myoclonus, usually with autosomal dominant inheritance.

  • Etat cribl

    Holes that are seen in the brain due to enlarged perivascular or Virchow-Robin spaces.

  • Etat porose

    Holes in the brain due to postmortem gas formation.

  • ETF

    electron transfer flavoprotein

  • Ethmocephaly

    Intraocular proboscis; ocular hypotelorism.

  • Exophthalmos

    Protrusion of the eyeball(s).

  • External auditory meatus

    The opening of the external auditory canal.

  • external globus pallidus

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • External neurolysis

    The surgical removal of scar tissue in a circumferential fashion from around an injured peripheral nerve.

  • Extinction

    Unawareness of a stimulus on one side only when there is a competing stimulus on the opposite side

  • Extrapyramidal

    Outside the pyramidal tract; generally referring to disorders of the basal ganglia.

  • Exudative vitreoretinopathy

    Fibrous or exudative adhesions of vitreous and retina

  • Eyelid myoclonia with absences

    Childhood-onset epileptic syndrome characterized by eyelid myoclonus, brief absences, photosensitivity, and normal intellect.

  • FAB

    familial amyloidosis-British type

  • FABP

    fatty acid-binding protein

  • Face of the giant panda

    Symmetric bilateral hyperintensities of the midbrain and pons seen on axial T2-MRI in Wilson disease. Resembles the "hot cross bun" sign described in multiple system atrophy.

  • Face of the giant panda sign

    Symmetric bilateral hyperintensities of the midbrain and pons seen on axial T2-MRI in Wilson disease. Resembles the "hot cross bun" sign described in multiple system atrophy.

  • Face of the panda cub

    Symmetric bilateral hyperintensities in the dorsal pons seen on axial T2-MRI in Wilson disease.

  • Face of the panda cub sign

    Symmetric bilateral hyperintensities in the dorsal pons seen on axial T2-MRI in Wilson disease.

  • Face-of-the-giant-panda

    Symmetric bilateral hyperintensities of the midbrain and pons seen on axial T2-MRI in Wilson disease. Resembles the "hot cross bun" sign described in multiple system atrophy.

  • Face-of-the-panda-cub

    Symmetric bilateral hyperintensities in the dorsal pons seen on axial T2-MRI in Wilson disease.

  • Factor V Leiden

    A mutation (1691 G to A, leading to Arg506 to Gln) in the gene for coagulation factor V that causes a hypercoagulable state.

  • FADH2

    flavin adenine dinucleotide

  • FALDH

    fatty aldehyde dehydrogenase

  • Fanconi syndrome

    Disorders of renal tubular function.

  • Fanconi's syndrome

    Disorders of renal tubular function.

  • FAPI

    Fibroblast activation protein imaging

  • Farber bodies

    Curvilinear lipid cytoplasmic inclusion bodies seen in macrophages under electron microscopy in Farber disease.

  • Farber body

    Curvilinear lipid cytoplasmic inclusion bodies seen in macrophages under electron microscopy in Farber disease.

  • FAS

    fetal alcohol syndrome

  • FASI

    focal areas of signal intensity

  • FDA

    United States Food and Drug Administration

  • FDG

    18-fluorodeoxyglucose

  • FDG-PET

    18-fluorodeoxyglucose positron emission tomography

  • febrile convulsion

    Otherwise unprovoked seizures that occur in the setting of fever in infants and children between 3 months and 5 years of age.

  • Febrile convulsions

    Otherwise unprovoked seizures that occur in the setting of fever in infants and children between 3 months and 5 years of age.

  • FEBRT

    focal external beam radiation therapy

  • Femoral neuropathies

    A disorder characterized by selective dysfunction of the femoral nerve(s) due to axonal loss or segmental demyelination or both.

  • Femoral neuropathy

    A disorder characterized by selective dysfunction of the femoral nerve(s) due to axonal loss or segmental demyelination or both.

  • FEP

    free erythroprotoporphyrin

  • Fetal alcohol effects

    Syndrome due to intrauterine fetal exposure to ethanol, and characterized by two of the following criteria: (1) prenatal or postnatal growth retardation, (2) developmental delay or intellectual impairment, and (3) at least two of the following craniofacial abnormalities: microcephaly, shortened palpebral fissures, poorly developed philtrum, thin upper vermillion, or flattened maxillary area.

  • Fetal alcohol spectrum disorder

    The range of outcomes caused by prenatal exposure to alcohol. This term is not a diagnosis but is used principally for research purposes and recognizes the important fact that exposure to alcohol during development can induce damage to the brain or other organs without causing the full fetal alcohol syndrome.

  • Fetal alcohol syndrome

    A constellation of developmental defects caused by intrauterine exposure to ethanol and characterized by the following 3 criteria: (1) prenatal or postnatal growth retardation, (2) neurodevelopmental abnormalities, and (3) a characteristic set of midfacial abnormalities, which include shortened palpebral fissures, poorly developed philtrum, thin upper vermillion, and flattened maxillary area.

  • FEV1/FVC

    ratio of one-second expiratory volume to vital capacity

  • FGF3

    fibroblast growth factor 3 gene

  • FGFR

    fibroblast growth factor receptor

  • FiCO2

    percent inspired carbon dioxide

  • Final awakening

    The amount of wakefulness that occurs after the final wake-up time until the arise time (lights on).

  • Final wake-up

    The clock time at which an individual awakens for the last time before the arise time.

  • FiO2

    percent inspired oxygen

  • First night effect

    The effect of the environment and polysomnographic recording apparatus on the quality of the subject's sleep the first night of recording. Sleep is usually of reduced quality compared to that which would be expected in the subject's usual sleeping environment, without electrodes and other recording procedure stimuli. The subject usually will habituate to the laboratory by the time of the second night of recording.

  • Floppy infant

    An infant whose muscles and joints do not show normal resistance when moved passively. This is most noticeable when the infant is passively lifted against gravity.

  • floppy infants

    An infant whose muscles and joints do not show normal resistance when moved passively. This is most noticeable when the infant is passively lifted against gravity.

  • Fluent agraphia

    Writing disturbance associated with fluent aphasia. Writing is abundant, calligraphy is normal, but a significant amount of errors in letters and words are observed.

  • Fluent aphasia

    Language disorder with normal rate and ease of word production.

  • Fluorescent in situ hybridization

    The essential steps of the procedure are preparation of the specimen, probe-labeling, hybridization, and detection. Several methods are used for detection.

  • Fluorodopa

    A radiolabeled tracer used in positron emission tomography to measure dopaminergic neuronal function.

  • FMD

    fibromuscular dysplasia

  • FMR1

    fragile X mental retardation-1

  • FMR2

    fragile XE menatal retardation-2

  • fMRI

    Functional magnetic resonance imaging, which uses radio waves and intense magnetic fields to photograph and measure regional cerebral metabolism during a specified task.

  • FMRP

    fragile X mental retardation protein

  • FOLA

    Familial oculo-leptomeningeal amyloidosis

  • Folic acid

    A vitamin that is required for some methyl transfer reactions. Deficiency of folic acid causes megaloblastic anemia and hyperhomocysteinemia.

  • FPZ

    frontopolar zed (midline)

  • fra X

    fragile X

  • Freebase cocaine

    Alkaloidal cocaine.

  • Frontal acalculia

    Disturbance in calculation abilities resulting from a frontal lobe damage. It is associated with: attentional difficulties, perseveration, and impairments of complex mathematical concepts.

  • Frontal leukodystrophy

    Greatest white matter loss in the frontal lobes.

  • Frontal lobe dementia

    Insidious and progressive deterioration in executive cognition.

  • frontal lobe dementias

    Insidious and progressive deterioration in executive cognition.

  • frontal-executive function

    Functions thought to be subserved by the frontal lobe. These include organizing, sequencing, and planning; mental flexibility and adaptability; maintaining and changing a cognitive set; and abstraction, judgment, and reasoning.

  • Frontal-executive functions

    Functions thought to be subserved by the frontal lobe. These include organizing, sequencing, and planning; mental flexibility and adaptability; maintaining and changing a cognitive set; and abstraction, judgment, and reasoning.

  • FS+

    febrile seizures plus

  • FSH

    follicle-stimulating hormone

  • FSHD

    facioscapulohumeral dystrophy (or disease)

  • FSHMD

    facioscapulohumeral muscular dystrophy

  • FTA-ABS

    fluorescent treponemal antibody absorption (test)

  • FTLD-T

    frontotemporal lobar degeneration-tauopathy

  • FTLD-U

    frontotemporal lobar degeneration-ubiquinopathy

  • Functionally autonomous insomnia

    Insomnia no longer associated with its initial cause.

  • FUT-175

    nafamostat mesilate

  • FVIIa

    activated factor VII

  • FXTAS

    Fragile X-associated tremor/ataxia syndrome

  • FZ

    frontal zed (midline)

  • G6PD

    glucose-6-phosphate dehydrogenase

  • GAA

    guanine-adenosine-adenosine

  • GABA

    gamma-aminobutyric acid

  • GABHS

    group A beta-hemolytic streptococcus

  • GAD

    glutamic acid decarboxylase

  • GALE

    Uridine diphosphate galactose-4-epimerase deficiency

  • GALK

    Galactokinase deficiency

  • GALT

    galactose-1-phosphate uridyltransferase

  • Gaucher disease

    An autosomal recessive lipidosis caused by glucocerebrosidase deficiency, and resulting in abnormal lysosomal storage of glucosylceramide in the cells of the reticuloendothelial system. Separated into type 1 (adult) chronic nonneuronopathic Gaucher disease, type 2 (infantile) acute neuronopathic Gaucher disease, and type 3 (juvenile) subacute neuronopathic Gaucher disease.

  • Gaucher's disease

    An autosomal recessive lipidosis caused by glucocerebrosidase deficiency, and resulting in abnormal lysosomal storage of glucosylceramide in the cells of the reticuloendothelial system. Separated into type 1 (adult) chronic nonneuronopathic Gaucher disease, type 2 (infantile) acute neuronopathic Gaucher disease, and type 3 (juvenile) subacute neuronopathic Gaucher disease.

  • GBM

    glioblastoma multiforme

  • GC

    gas chromatography (or glucocerebrosidase)

  • GCA

    giant cell arteritis

  • GCDH

    glutaryl-CoA dehydrogenase

  • GCS

    Glasgow Coma Scale

  • GCSF

    granulocyte colony stimulating factor

  • Gd-DTPA

    gadolinium-diethylenetriamine pentaacetic acid

  • GDNF

    glial cell line-derived neurotrophic factor

  • Gegenhalten

    Active resistance of any effort to examine or move a patient.

  • Gegenhalten (Paratonia)

    Active resistance of any effort to examine or move a patient.

  • Gelastic seizures

    Seizures characterized by unusual happiness or laughter and often linked with hypothalamic hamartomas.

  • Generalized seizures

    Seizures that initially involve both hemispheres, usually with impairment of consciousness at the outset. They include absence (typical or atypical), myoclonic, tonic, clonic, tonic-clonic, and atonic seizures.

  • Genu valgum

    A deformity with the knees abnormally close, ie, "knock kneed."

  • Gerstmann syndrome

    Acalculia, agraphia, right-left disorientation, and finger agnosia. It has been related with left angular gyrus pathology.

  • Gerstmann's syndrome

    Acalculia, agraphia, right-left disorientation, and finger agnosia. It has been related with left angular gyrus pathology.

  • GFAP

    glial fibrillary acidic protein

  • GGT

    gamma-glutamyl transferase

  • GH

    growth hormone

  • GHB

    gamma hydroxybutyrate acid

  • GI

    gastrointestinal

  • Giant aneurysm

    An aneurysm with a diameter that equals or exceeds 25 mm.

  • Gibbus

    A hump.

  • Glasgow coma scale

    A standardized scoring system used to assess severity of brain injury

  • Glial fibrillary acid protein

    A 51-kd intermediate filament expressed by neoplastic glial cells; an immunochemical staining technique that identifies glial cells by using antibodies directed against cytoplasmic glial fibrillary acidic protein.

  • Glial fibrillary acid protein (GFAP)

    A 51-kd intermediate filament expressed by neoplastic glial cells; an immunochemical staining technique that identifies glial cells by using antibodies directed against cytoplasmic glial fibrillary acidic protein.

  • Globus pallidus externa

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • globus pallidus external

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • Globus pallidus interna

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • globus pallidus internal

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • globus pallidus internus

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • Glu

    glutamine

  • Glucocerebroside

    A ceramide with a glucose moiety esterified to the C-1 of ceramide in a beta-glucosidic linkage.

  • Gluconeogenesis

    Production of new glucose from noncarbohydrate sources.

  • Glucosylceramide

    A ceramide with a glucose moiety esterified to the C-1 of ceramide in a beta-glucosidic linkage.

  • Glucosylceramide (Glucocerebroside)

    A ceramide with a glucose moiety esterified to the C-1 of ceramide in a beta-glucosidic linkage.

  • gly

    glycine

  • Glycosylation

    The collective term for the processes in which proteins and lipids are modified with carbohydrates.

  • GM1

    monosialoganglioside

  • GMP

    guanosine monophosphate

  • GnRH

    gonadotropin-releasing hormone

  • GON

    greater occipital nerve

  • GOS

    Glasgow Outcome Scale

  • GPA

    granulomatosis with polyangiitis (Wegener)

  • GPe

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • GPi

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • Gradenigo syndrome

    Petrositis with abducens paresis and trigeminal-distribution pain (often in the temporal region) typically resulting from suppurative otitis media spreading to the petrous apex and affecting the gasserian ganglion in Meckel's cave and the abducens nerve in Dorello's canal.

  • Gram-negative bacillary meningitis

    Meningitis due to Enterobacteriaceae, Pseudomonas aeruginosa, and other gram-negative bacteria.

  • Gram-positive meningitis

    Meningitis due to Staphylococcus aureus, coagulase-negative Staphylococcus, Streptococcus Group A, B (non-neonatal), and D, not including pneumococci or listeria.

  • Grasp reflex

    Involuntary clenching of the hand to tactile stimulation.

  • GSS

    Gerstmann-Straussler-Scheinker syndrome

  • GTCS

    generalized tonic-clonic seizures

  • GTP

    guanosine triphosphate

  • GTP cyclohydrolase deficiency

    An autosomal recessive or dominant disorder of tetrahydrobiopterin metabolism resulting in reduced synthesis of biogenic amine neurotransmitters. GTP cyclohydrolase is the first enzyme in the biosynthetic pathway for tetrahydrobiopterin synthesis. Symptoms and signs in the recessive form are similar to those in other tetrahydrobiopterin disorders, with notable features of greatly reduced neopterin and biopterin in urine and cerebrospinal fluid after oxidation. The dominant form leads to dopa-responsive dystonia.

  • Gumma

    Tertiary syphilitic granulomas.

  • GUSTO

    Global Utilization of Streptokinase and tPA for Occluded Arteries

  • H-CC

    hypoplastic corpus callosum

  • H-reflex

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • H-reflexes

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • H-wave

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • H-wave (Hoffmann reflex)

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • H-waves

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • HAART

    highly active antiretroviral therapy

  • HAH1

    human ATX1 homologue

  • HAM/TSP

    HTLV-1 associated myelopathy/tropical spastic paraparesis

  • Hamartoma

    An overgrowth in an organ of cytologically normal cells that are native to that organ, forming a discrete mass.

  • HaNDL

    headache associated with neurologic deficits and cerebrospinal fluid lymphocytosis

  • Haplotype

    The combination of alleles for different genes that are close together on the same chromosome and tend to be inherited together.

  • Haplotypes

    The combination of alleles for different genes that are close together on the same chromosome and tend to be inherited together.

  • HBO

    hyperbaric oxygen

  • HBsAb

    hepatitis B virus surface antibody

  • HBsAg

    hepatitis B virus surface antigen

  • HBV

    hepatitis B virus

  • HCCAA

    Hereditary Cystatin C Amyloid Angiopathy

  • hCG

    human chorionic gonadotrophin

  • HCG (or hCG)

    human chorionic gonadotrophin

  • HCHWA-D

    Hereditary Cerebral Hemorrhage with Amyloidosis-Dutch type

  • HCHWA-F

    Hereditary Cerebral Hemorrhage with Amyloidosis-Flemish type

  • HCHWA-I

    Hereditary Cerebral Hemorrhage with Amyloidosis-Icelandic type

  • HCI

    hemocytology index

  • HDL

    high-density lipoprotein

  • Headache associated with ischemic cerebrovascular disease

    The headache of ischemic cerebrovascular disease is equally likely to be abrupt or gradual in onset, and the quality of pain varies widely among patients. The headache is usually unilateral, focal, and of mild to moderate severity. It is frequently frequently associated with nausea, vomiting, and photophobia and phonophobia. It is theorized that the headache is mostly related to electrochemical or mechanical stimulation of the trigeminovascular afferent system.

  • Heat shock protein

    These are essential for cell viability and are considered to offer protection from harmful conditions by binding to improperly folded or denatured proteins that accumulate during stress. Heat shock proteins protect cells from oxidative stress, heat shock, toxins, and cellular damage following ischemia or sepsis-induced injury.

  • HELLP

    hemolytic anemia, elevated liver enzymes, low platelets

  • Hemeralopia

    Defective vision in bright light, or "day blindness."

  • Hemianopia

    Loss of vision for one half of the visual field for one or both eyes.

  • Hemicrania continua

    A headache disorder, often responsive to indomethacin, consisting of continuous lateralized dull aching, with superimposed jolts of pain and attacks of pounding severe pain ipsilateral to the dull ache.

  • Hemihypesthesia

    Hemisensory deficit.

  • Hemosiderin

    A breakdown product of hemoglobin.

  • Hennebert's sign

    Pressure-induced vertigo, nystagmus, or both elicited by insufflation of the external auditory canal. It is often a sign of perilymphatic fistulae and Meniere syndrome.

  • HEPA-VAC

    high-efficiency particle accumulator vacuum cleaner

  • Hereditary homocystinuria

    An autosomal recessive disease caused by deficiency of cystathionine beta-synthase.

  • HERNS

    hereditary endotheliopathy with retinopathy, nephropathy, and stroke

  • Hertel exophthalmometry

    A method of measuring the protrusion of the cornea relative to the lateral orbital rim by a particular device. Upper limits of normal are defined based on sex and racial group.

  • Hertel's exophthalmometry

    A method of measuring the protrusion of the cornea relative to the lateral orbital rim by a particular device. Upper limits of normal are defined based on sex and racial group.

  • Heteromodal

    A qualifier for populations of neurons that receive input from more than one sensory modality and from other heteromodal populations of neurons either individually or collectively, eg, heteromodal neocortex; similar to 'multimodal.'

  • Heterotopia

    Normal tissue in an abnormal location. Specifically, displacement of gray matter into the deep white matter.

  • Heterotopias

    Normal tissue in an abnormal location. Specifically, displacement of gray matter into the deep white matter.

  • HEXA

    hexosaminidase A

  • HEXB

    hexosaminidase B

  • Hexosaminidase A

    Enzyme composed of alpha and beta subunits.

  • Hexosaminidase B

    Enzyme composed of two beta subunits.

  • HgA1C

    hemoglobin A1C

  • HHH

    hyperornithinemia-hyperammonemia-homocitrullinuria

  • HHHO

    hypotonia-hypomentia-hypogonadism-obesity (syndrome)

  • HHNK

    hyperglycemic hyperosmolar nonketotic state

  • HHT

    hereditary hemorrhagic telangiectasia

  • HHV

    human herpes virus

  • HIAA

    hydroxyindoleacetic acid

  • Hib

    Haemophilus influenzae type b

  • Hirschprung's disease

    Congenital megacolon from colonic agangliosidosis.

  • HIV

    human immunodeficiency virus

  • HIV-1

    human immunodeficiency virus type 1

  • HKAFO

    hip-knee-ankle-orthosis

  • HLA

    human leukocyte antigen

  • HLA-DR

    human leukocyte antigen, locus DR

  • HMG

    3-hydroxy-3-methylglutarate

  • HMG-CoA

    3-hydroxy-3-methylglutaryl-coenzyme A

  • HMG-CoA lyase deficiency

    An autosomal recessive disorder of organic acid metabolism with onset often within the first year of life. Symptoms of vomiting, tachypnea, and lethargy are seen with associated nonketotic aciduria, hypoglycemia, and hyperammonemia.

  • HmPAO

    hexamethylpropyleneaminoeoxime

  • HNPP

    hereditary neuropathy with liability to pressure palsies

  • Hoffman Reflex

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • Hoffmann Reflexes

    The electrically elicited spinal monosynaptic reflex that bypasses the muscle spindles.

  • Homocysteine

    A sulfur-containing amino acid derived from metabolism of methionine.

  • Homogentisic acid oxidase deficiency

    A rare inherited disorder of metabolism, characterized by urine that turns black when exposed to air. Another characteristic is the development of arthritis in adulthood. Also known as ochronosis or homogentisic acid oxidase deficiency.

  • Homovanillic acid

    A major metabolite of dopa, dopamine, and norepinephrine that is detectable in the blood, urine, and cerebrospinal fluid.

  • Horschprung disease

    Congenital megacolon from colonic agangliosidosis.

  • Hot cross bun

    Cruciform signal hyperintensity in the mid-pons seen in multiple system atrophy. Resembles "face of the giant panda" sign, described in Wilson disease.

  • Hot cross bun sign

    Cruciform signal hyperintensity in the mid-pons seen in multiple system atrophy. Resembles "face of the giant panda" sign, described in Wilson disease.

  • Hot-cross-bun

    Cruciform signal hyperintensity in the mid-pons seen in multiple system atrophy. Resembles "face of the giant panda" sign, described in Wilson disease.

  • HPE

    holoprosencephaly

  • HPLC

    high-performance liquid chromatography

  • HPRT

    hypoxanthine-guanine phosphoribosyltransferase

  • HRQL

    health-related quality of life

  • HS

    heparan sulfate

  • HSAN

    hereditary sensory and autonomic neuropathy

  • HSES

    hemorrhagic shock and encephalopathy syndrome

  • Hsp40

    heat shock protein 40

  • Hsp60

    heat shock protein 60

  • HSV

    herpes simplex virus

  • HSV-1

    herpes simplex virus type 1

  • HSV-2

    herpes simplex virus type 2

  • HTLV

    human T-cell lymphotropic virus

  • HTLV-1

    human T cell lymphotropic virus type 1

  • HU

    hydroxyurea

  • Hummingbird

    Atrophy of the rostral and caudal midbrain tegmentum seen on sagittal T1-MRI in progressive supranuclear palsy may resemble the bill of a hummingbird.

  • Hummingbird sign

    Atrophy of the rostral and caudal midbrain tegmentum seen on sagittal T1-MRI in progressive supranuclear palsy may resemble the bill of a hummingbird.

  • Hurler syndrome

    An autosomal recessive mucopolysaccharide caused by deficiency of alpha-L-iduronidase. Characterized by excretion of dermatan sulfate and heparan sulfate in the urine. Onset is usually around 1 year with symptoms of progressive mental deterioration, gargoyle facies, kyphosis, dwarfism, dysotosis multiplex, hepatosplenomegaly, and cardiac defects. Death occurs by 10 years, usually by respiratory infection or heart failure. Also known as mucopolysaccharidosis I-H.

  • Hurler-Scheie syndrome

    Intermediate autosomal recessive syndrome between mucopolysaccharidosis I-H and mucopolysaccharidosis I-S. Caused by deficiency of alpha-L-iduronidase. Symptoms consist of hearing loss, visual impairment, dysotosis multiplex pachymeningitis cervicalis, and little or no intellectual dysfunction. Also known as mucopolysaccharidosis I-H/S.

  • Hutchinson teeth

    Notched incisors.

  • Hutchinson triad

    Notched incisors, eighth cranial nerve deafness, and interstitial keratitis.

  • Hutchinson's teeth

    Notched incisors.

  • Hutchinson's triad

    Notched incisors, eighth cranial nerve deafness, and interstitial keratitis.

  • Hutchinson-Gilford syndrome

    Extremely rapid aging from unknown etiology with death within the first decade.

  • HVA

    homovanillic acid

  • HVF

    humphrey visual field

  • HVJ

    hemagglutinating virus of Japan

  • Hydrophobia

    Fear of water in rabies patients due to uncomfortable contractions of the diaphragm and other inspiratory muscles, which may be precipitated by attempts to swallow.

  • Hyperalgesia

    (From hyper, increased, and algesia, pain) Increased pain from a stimulus that normally provokes pain.

  • Hypercapnia

    Elevated carbon dioxide level in blood.

  • hyperCKemia

    hypercreatinekinasemia

  • Hypercoagulable state

    Any prothrombotic condition caused by a specific disorder of blood coagulation.

  • Hypereosinophilic syndrome

    A systemic disease characterized by idiopathic eosinophilia (> 1500/mm3 ) of at least 6 months duration, or of less duration if there already is evidence of organ involvement by eosinophils or related mechanisms.

  • Hyperesthesia

    (From hyper, increased, and esthesia, sensation) Increased sensitivity to stimulation, excluding the special senses, defined as a reduced threshold.

  • Hyperimmune response

    Immunologic response greater than that expected as a normal response to foreign antigen.

  • Hyperimmune responses

    Immunologic response greater than that expected as a normal response to foreign antigen.

  • Hyperkinetic seizures

    Seizures with bizarre hyperactive automatisms.

  • Hypermutation

    Increased number of mutations in a genome beyond that expected by chance; associated with defined regions of a genome, often designated "hot areas."

  • Hyperpathia

    (Hyper, increased, and pathia, suffering) A painful syndrome characterized by an abnormally painful reaction to a stimulus, especially a repetitive stimulus, as well as an increased threshold.

  • hyperPP

    hyperkalemic periodic paralysis

  • Hypertelorism

    Extreme width between two bodily parts (such as the eyes).

  • Hypertrophic neuropathies

    Neuropathy characterized by segmentary enlargement of nerve trunks, resulting from repeated cycles of demyelination and remyelination, as demonstrated by the presence of onion bulbs.

  • Hypertrophic neuropathy

    Neuropathy characterized by segmentary enlargement of nerve trunks, resulting from repeated cycles of demyelination and remyelination, as demonstrated by the presence of onion bulbs.

  • Hyperventilation syndrome

    A syndrome characterized by a variety of somatic symptoms induced by physiologically inappropriate hyperventilation and usually reproduced in whole or in part by voluntary hyperventilation.

  • Hypesthesia

    (From hypo, reduced, and esthesia, sensation) Reduced sensation to a particular modality, often included in the term (eg, hypesthesia to temperature sensation), defined experimentally as increased threshold to that modality.

  • Hypnagogic

    Occurrence of an event during the transition from wakefulness to sleep.

  • Hypnagogic hallucination

    Vivid sensory images occurring at sleep onset, but particularly vivid with sleep-onset REM periods. A feature of narcoleptic naps, when the onset occurs with REM sleep.

  • Hypnagogic hallucinations

    Vivid sensory images occurring at sleep onset, but particularly vivid with sleep-onset REM periods. A feature of narcoleptic naps, when the onset occurs with REM sleep.

  • Hypnagogic imagery

    Vivid sensory images occurring at sleep onset, but particularly vivid with sleep-onset REM periods. A feature of narcoleptic naps, when the onset occurs with REM sleep.

  • Hypnagogic startle

    A "sleep start" or sudden body (hypnic jerk), observed normally just at sleep onset and usually resulting, at least momentarily, in an awakening.

  • Hypnagogic startles

    A "sleep start" or sudden body (hypnic jerk), observed normally just at sleep onset and usually resulting, at least momentarily, in an awakening.

  • Hypnopomic

    Occurrence of an event during the transition from sleep to wakefulness at the termination of a sleep episode.

  • Hypnopompic

    Occurrence of an event during the transition from sleep to wakefulness at the termination of a sleep episode.

  • Hypnopompic (Hypnopomic)

    Occurrence of an event during the transition from sleep to wakefulness at the termination of a sleep episode.

  • Hypnotic-dependent sleep disorder

    Insomnia or daytime sleepiness associated with hypnotic use and a pronounced difficulty in discontinuing the hypnotic medication due to the worsening of sleep, sleepiness, or other patient distress.

  • Hypoalgesia

    (From hypo, reduced and algesia, pain) Diminished pain in response to a normally painful stimulus.

  • hypoesthesia

    Decreased sensitivity to stimulation, excluding the special senses.

  • Hypokinesia

    Reduced voluntary motor activity in a body part.

  • Hypopnea

    A episode of shallow breathing (airflow reduced by at least 50%) during sleep lasting 10 seconds or longer, usually associated with a fall in blood oxygen saturation.

  • hypoPP

    hypokalemic periodic paralysis

  • Hypospadia

    Developmental anomaly with urethral wall defect opening into the vagina or the underside of the penis.

  • Hypothalamic hamartoma

    A developmental brain disorder of a non-growing lesion most often attached in the 3rd cerebral ventricle and associated with gelastic seizures and developmental delay.

  • I-cell

    inclusion cell

  • I-cell disease

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis II.

  • Iatrogenic

    An adverse event that results from treatment.

  • IBM

    inclusion body myositis

  • IBT

    The clock time at which a person gets into bed. The into bed time (IBT) will be the same as the bedtime for many people, but not for those who spend time in wakeful activities in bed, such as reading, before attempting to sleep.

  • IBZM

    iodine-123-iodobenzamide

  • ICA

    internal carotid artery

  • ICCA

    infantile convulsions and charcoathetosis

  • ICEES

    International Classification of Epilepsies and Epileptic Syndromes

  • Ichthyosis

    A congenital skin condition that causes the epidermis to become dry and rough like fish scales.

  • ICP

    intracranial pressure

  • ICSD

    International Classification of Sleep Disorders

  • ICSD sleep code

    A code number of the International Classification of the Sleep Disorders (ICSD) that refers to modifying information of a diagnosis, such as associated symptom, severity, and duration of a sleep disorder.

  • ICU

    intensive care unit

  • IDDM

    insulin-dependent diabetes mellitus

  • Ideomotor apraxia

    Impaired skill performance due to improper reproduction of the required movement sequences or the spatial configuration of the involved body part, not attributable to weakness, incoordination, sensory loss, or failure to understand the task.

  • IFN

    interferon

  • IgA

    immunoglobulin A

  • IgD

    immunoglobulin D

  • IgE

    immunoglobulin E

  • IGF

    insulinlike growth factor

  • IgG

    immunoglobulin G

  • IgG4

    Immunoglobulin G4

  • IgG4-H

    Immunoglobulin G4-related hypophysitis

  • IgG4-HP

    Immunoglobulin G4-related hypertrophic pachymeningitis

  • IgG4-RD

    Immunoglobulin G4-related disease

  • IgM

    immunoglobulin M

  • IgM/G

    immunoglobulin M/G

  • IGS

    image-guided system

  • IHS

    International Headache Society

  • IL

    interleukin

  • IL-1

    interleukin-1

  • IL-12

    interleukin-12

  • IL-1ra

    interleukin-1 receptor antagonist

  • IL-2

    interleukin-2

  • IL-6

    interleukin-6

  • IL1-beta

    interleukin 1-beta

  • ILAE

    International League Against Epilepsy

  • ILS

    isolated lissencephaly sequence

  • Imitation behavior

    Disinhibited copying of another person's speech or actions, synonymous with the terms echolalia and echopraxia.

  • Immediate memory

    The shortest time-frame memory system that operates over seconds. It is sometimes referred to as registration.

  • Immediate posttraumatic seizure

    An epileptic seizure that occurs within 5 minutes of head trauma.

  • immediate posttraumatic seizures

    An epileptic seizure that occurs within 5 minutes of head trauma.

  • Immune reconstitution inflammatory syndrome

    A group of different inflammatory disorders, which are associated with paradoxical deterioration of various preexisting infectious processes following commencement of highly active antiretroviral therapy in HIV-infected patients.

  • Imprinting

    The differential expression of a gene depending on the parent from whom it was inherited. This would allow similar deletions to have different phenotypic expression.

  • In situ hybridization

    A powerful and versatile tool for detection and localization of nucleic acid sequences within an intact cell, chromosome, or a tissue preparation by means of labeled complementary sequences.

  • INCL

    infantile neuronal ceroid lipofuscinosis

  • INF

    interferon

  • INR

    international normalized ratio

  • Interleukin

    Soluble factors released by immune and nonimmune cells, which regulate immune responses.

  • Intermediary sleep stage

    A term sometimes used for NREM stage 2 sleep. See Deep Sleep; Light Sleep. Often used, especially in the French literature, for stages combining elements of stage 2 and REM sleep.

  • Internal arousal insomnia

    Insomnia associated with increased activity in the reticular activating system.

  • Internal desynchronization

    A situation where different circadian rhythms are not entrained to a fixed external rhythm, resulting in potentially symptomatic phase angle differences between the rhythms.

  • internal globus pallidus

    A major output structure, in conjunction with the substantia nigra reticulata, of the basal ganglia.

  • Into bed time

    The clock time at which a person gets into bed. The into bed time (IBT) will be the same as the bedtime for many people, but not for those who spend time in wakeful activities in bed, such as reading, before attempting to sleep.

  • Intracerebral hemorrhage

    Bleeding into the substance of the brain.

  • Intracranial epidural abscess

    Infection occurring between the outermost layer of the meninges, the cranial dura, and the overlying skull.

  • intracranial epidural abscesses

    Infection occurring between the outermost layer of the meninges, the cranial dura, and the overlying skull.

  • Intracranial subdural empyema

    Infection occurring between the outermost layer of the cranial meninges, the dura, and the cranial arachnoid.

  • Intractable epilepsy

    Seizures not controlled with anti-seizure medications. By definition, therapy-resistant epilepsy consists of more than 1 seizure per month.

  • Intraluminal

    Within the lumen of a vessel.

  • Intramedullary spinal cord metastasis

    Invasion of the parenchyma of the spinal cord by a malignant solid tumor that arises outside the CNS.

  • intrinsic sleep disorder

    Disorders that either originate or develop from within the body, or arise from causes within the body. The intrinsic sleep disorders are a subgroup of the dyssomnias.

  • Intrinsic sleep disorders

    Disorders that either originate or develop from within the body, or arise from causes within the body. The intrinsic sleep disorders are a subgroup of the dyssomnias.

  • Intron

    A piece of DNA of unknown function that is interspersed between exons.

  • ion pump

    Specialized membrane proteins that convert metabolic energy into the work of moving ions across membranes against their electrochemical gradient.

  • Ion pumps

    Specialized membrane proteins that convert metabolic energy into the work of moving ions across membranes against their electrochemical gradient.

  • IOPD

    infantile-onset Pompe disease

  • IP3

    inositol triphosphate

  • IPW

    imprinted gene in the PWS region

  • IQ

    intelligence quotient

  • IRLS

    International Restless Legs Severity Scale

  • Irregular sleep-wake pattern

    Temporally disorganized and irregular sleep and waking behavior, where sleep is broken into three or more short blocks in the period of 24 hours, with marked day-to-day variability of sleep and wake periods and with no circadian or ultradian pattern.

  • Isolated beta-methylcrotonyl-CoA carboxylase deficiency

    An inherited disorder of organic acid metabolism that is characterized by neurologic symptoms and ketoacidosis.

  • IST

    International Stroke Trial

  • IT15

    interesting transcript 15 (gene on short arm of chromosome 4 implicated in Huntington disease)

  • IVIG

    intravenous immunoglobulin

  • IVP

    intravenous pyelogram

  • Jackson-Weiss syndrome

    A rare genetic disorder characterized by distinctive malformations of the head and facial (craniofacial) area and abnormalities of the feet. The range and severity of symptoms and findings may be extremely variable, including among affected members of the same family. However, primary findings may include premature closure of the fibrous joints (cranial sutures) between certain bones of the skull (craniosynostosis); unusually flat, underdeveloped midfacial regions (midfacial hypoplasia); abnormally broad great toes; and/or malformation or fusion of certain bones within the feet. In some cases, Jackson-Weiss syndrome may result from new genetic changes that appear to occur randomly for unknown reasons. In other affected individuals, the disorder may be inherited as an autosomal dominant trait.

  • Jacksonian seizures

    Clonic seizures with spread to adjacent muscle groups.

  • Jacobson's nerve

    The tympanic branch of the glossopharyngeal nerve.

  • JCV

    JC virus

  • JNCL

    juvenile neuronal ceroid lipofuscinosis

  • JWS

    A rare genetic disorder characterized by distinctive malformations of the head and facial (craniofacial) area and abnormalities of the feet. The range and severity of symptoms and findings may be extremely variable, including among affected members of the same family. However, primary findings may include premature closure of the fibrous joints (cranial sutures) between certain bones of the skull (craniosynostosis); unusually flat, underdeveloped midfacial regions (midfacial hypoplasia); abnormally broad great toes; and/or malformation or fusion of certain bones within the feet. In some cases, Jackson-Weiss syndrome may result from new genetic changes that appear to occur randomly for unknown reasons. In other affected individuals, the disorder may be inherited as an autosomal dominant trait.

  • K complex

    A sharp, negative EEG wave followed by a high-voltage slow wave. The complex duration is at least 0.5 seconds, and may be accompanied by a sleep spindle. K complexes occur spontaneously during NREM sleep, and begin and define stage 2 sleep. They are thought to be evoked responses to internal stimuli. They can also be elicited during sleep by external (particularly auditory) stimuli.

  • K complexes

    A sharp, negative EEG wave followed by a high-voltage slow wave. The complex duration is at least 0.5 seconds, and may be accompanied by a sleep spindle. K complexes occur spontaneously during NREM sleep, and begin and define stage 2 sleep. They are thought to be evoked responses to internal stimuli. They can also be elicited during sleep by external (particularly auditory) stimuli.

  • K+

    Serum potassium

  • K-Alpha

    A K complex followed by several seconds of alpha rhythm; a type of microarousal.

  • Keratoconjunctivitis sicca

    Dryness of the conjunctiva and cornea.

  • Ketogenesis

    Formation of ketone bodies.

  • Ketosis

    A condition resulting from the buildup of ketone bodies when lipids are metabolized.

  • Kindling

    The process in which a progressively increased seizure response occurs to a stimulus that initially is insufficient to induce a seizure and eventually results in seizures independent of the stimulus.

  • Kleeblattsch

    A congenital malformation in which the skull bones join to from three lobes. The condition may also be associated with hydrocephalus and facial and skeletal deformities. Also known as kleeblattsch.

  • Kleeblattschadel syndrome

    A congenital malformation in which the skull bones join to from three lobes. The condition may also be associated with hydrocephalus and facial and skeletal deformities. Also known as kleeblattsch.

  • Kleeblattschidel syndrome

    A congenital malformation in which the skull bones join to from three lobes. The condition may also be associated with hydrocephalus and facial and skeletal deformities. Also known as kleeblattsch.

  • Km

    Michaelis' constant

  • Krebs cycle

    Energy-producing cycle that takes place in the cell's mitochondria.

  • KSS

    Kearns-Sayre syndrome

  • L-2 hydroxyglutaric aciduria

    Disease of unknown etiology and genetic basis, presenting after the first 6 months of life with nonspecific developmental delay, ataxia, mental retardation, dysarthria, spastic paresis, macrocephaly by exam, subcortical leukoencephalopathy and cerebellar atrophy by MRI, and increased L-2 stereoisomer of hydroxyglutaric acid in urine, plasma, and CSF by gas chromatography.

  • L-dopa

    levodopa

  • L-DOPS

    L-threo-dihydroxyphenylserine

  • L-FABP

    liver-type fatty acid-binding protein

  • L1CAM

    L1 cell adhesion molecule

  • Lacuna

    Small, deep cerebral infarct, which in the chronic state is represented by an irregular, small cystic lesion in the deep brain, brainstem, or cerebellum.

  • lacunae

    Small, deep cerebral infarct, which in the chronic state is represented by an irregular, small cystic lesion in the deep brain, brainstem, or cerebellum.

  • Lacunar gait

    Gait apraxia, with gait disturbance characterized by appearance of feet glued to the floor.

  • Lafora body disease

    An autosomal recessive progressive myoclonic epilepsy associated with the triad of severe myoclonus, generalized epilepsy, and dementia and pathologically with Lafora body (PAS-positive) inclusions seen throughout the nervous system.

  • Lagophthalmos

    Incomplete eyelid closure.

  • LAK

    lymphokine-activated killer

  • Lambdoid synostosis

    A rare condition in which there is premature unilateral or bilateral fusion of the lambdoid suture. Also known as occipital plagiocephaly.

  • LAMM

    labyrinthine aplasia, microtia, and microdontia

  • LAMM syndrome

    Autosomal recessive form of syndrome deafness with key clinical features of labyrinthine aplasia, microtia, and microdontia due to homozygous mutations in the fibroblast growth factor 3 (FGF3) gene. LAMM syndrome is one cause of Michel deformity.

  • Laryngeal dystonia

    Can be divided into (1) adductor spasmodic dysphonia, which is the result of the vocal cords' hyperadducting, creating a strained, choked voice, and (2) abductor spasmodic dysphonia, resulting from the vocal cords' being pulled apart, creating a weak, breathy voice.

  • Late congenital syphilis

    Congenital syphilis clinically manifested after 2 years of age.

  • late posttraumatic seizure

    Epileptic seizures that result from head trauma but occur more than 1 month after the head injury.

  • Late posttraumatic seizures

    Epileptic seizures that result from head trauma but occur more than 1 month after the head injury.

  • Late Whiplash Syndrome

    Refers to persistent symptoms present more than 6 months after an accident.

  • Latent myofascial trigger point

    A trigger point that is clinically quiescent with respect to spontaneous pain: it is painful only when palpated.

  • latent myofascial trigger points

    A trigger point that is clinically quiescent with respect to spontaneous pain: it is painful only when palpated.

  • LCC

    lipoma of the corpus callosum

  • LCMV

    lymphocytic choriomeningitis virus

  • LCR

    ligase chain reaction

  • LCS

    long-chain acyl-CoA synthetase

  • LD50

    Dose needed to kill 50% of test subjects.

  • LDH

    lactate dehydrogenase

  • LDL

    low-density lipoprotein

  • Learned insomnia

    Insomnia based on having acquired a habit of excessive concern with one's ability to sleep or a conditioned arousal to the stimuli surrounding sleep.

  • Leber hereditary optic neuropathy

    A maternally inherited optic neuropathy typically characterized by decreased acuity, a visual field defect involving the blind spot and central fixation (ie, cecocentral scotoma), and a characteristic pseudoedema of the optic disc that does not leak on fluorescein angiography.

  • Leber's hereditary optic neuropathy

    A maternally inherited optic neuropathy typically characterized by decreased acuity, a visual field defect involving the blind spot and central fixation (ie, cecocentral scotoma), and a characteristic pseudoedema of the optic disc that does not leak on fluorescein angiography.

  • Leonine facies

    Face of a leprosy patient resembling the face of a lion.

  • LETM

    longitudinally extensive transverse myelitis

  • leu

    leucine

  • Leucoderm

    Several areas of hypopigmented skin.

  • Leucoderm/leukoderma

    Several areas of hypopigmented skin.

  • Leukocoria

    White pupillary reflexes

  • Leukoderma

    Several areas of hypopigmented skin.

  • Leukoencephalopathies

    Disorder of cerebral white matter producing neurologic dysfunction.

  • Leukoencephalopathy

    Disorder of cerebral white matter producing neurologic dysfunction.

  • Levator function

    Upper eyelid excursion from extreme downgaze to extreme upgaze.

  • LGI1

    leucine-rich glioma inactivated 1

  • LH

    luteinizing hormone

  • LHRH

    luteinizing hormone-releasing hormone

  • LIF

    leukemia inhibitory factor

  • Light-dark cycle

    The periodic pattern of light (artificial or natural) alternating with darkness.

  • light-dark cycles

    The periodic pattern of light (artificial or natural) alternating with darkness.

  • Limb dystonia

    Dystonia involving either the arm or leg. The majority of patients with dystonia of the limbs have a task-specific, or action-induced, disorder. At rest, most patients have no problem, but when patients write (writer's cramp), play an instrument (musician's cramp), or do other tasks, the dystonia becomes apparent. Similarly, foot dystonia often is present only when the patient attempts to walk.

  • Limb-kinetic apraxia

    Loss of the ability to make precise, fine, and individual finger movements.

  • LINAC

    linear accelerator

  • LINCL

    late infantile neuronal ceroid lipofuscinosis

  • Lipoprotein

    Important lipid-protein compounds with spherical hydrophobic core of triglycerides or cholesterol esters surrounded by an amphipathic monolayer of phospholipids, cholesterol and apolipoproteins. Classified according to their density: chylomicrons, VLDLD, LDL, HDL.

  • Lisch nodule

    Nodular clump of iris pigment cells, iris hamartoma.

  • Lissencephaly

    Cerebral malformation in which typical gyri and sulci do not form ("smooth brain").

  • Listerial rhombencephalitis

    Listerial infection of the brainstem.

  • LMWH

    low-molecular-weight heparinoid

  • LNA

    locked nucleic acid

  • Lobar atrophy

    Dementing disorder associated with predominately frontal and/or temporal lobe atrophy with involvement of both gray and white matter.

  • Lobar hemorrhage

    Bleeding into the parenchyma of the brain in one of the major lobes of the brain.

  • Lobar hemorrhages

    Bleeding into the parenchyma of the brain in one of the major lobes of the brain.

  • Logographic reading

    Reading systems based on meaningful units (morphemes, words).

  • Long-term memory

    Also known as semantic memory or remote memory, this memory system stores and retrieves events from the past (eg, personal history, public events, and vocabulary). It is probably stored diffusely in the cerebral cortex.

  • LOPD

    late-onset Pompe disease

  • LP

    lumbar puncture

  • LRPN

    lumbosacral radiculoplexus neuropathy

  • LSD

    lysergic acid diethylamide

  • LT

    leukotriene

  • Lumbar disc herniation

    Extrusion of nuclear material through a weakened annulus fibrosis.

  • lumbar disk herniation

    Extrusion of nuclear material through a weakened annulus fibrosis.

  • Lumbosacral radiculopathy

    Involvement of the lumbosacral roots to produce radicular symptoms and signs.

  • Lupuslike anticoagulant

    An antiphospholipid antibody that nonspecifically prolongs the activated partial thromboplastin time or other in vitro coagulation assays.

  • Luria hand sequences

    A test of motoric executive function in which the patient must learn and reproduce a sequence of hand positions (eg, flat-fist-edge).

  • LVEF

    left ventricular ejection fraction

  • LVT

    left ventricular thrombi

  • Lymphocyte transformation test

    Lymphocytes from previously exposed individuals will proliferate in response to antigens to which they have been exposed. This is an in vitro test that is felt to represent an in vivo T-cell response.

  • Lymphocytic choriomeningitis virus

    An arena virus and a common human pathogen that can cross the placenta and act as a neuroteratogen.

  • Lys

    Lysine

  • Lyst gene

    The lysosomal trafficking gene, the gene for Chediak-Higashi disease.

  • LYST protein

    The protein product of Lyst gene.

  • m-CPP

    meta-chloro-phenyl-piperazine

  • MADA

    myoadenylate deaminase

  • MAG

    myelin associated glycoprotein

  • MAGEL2

    melanoma antigen-like gene 2

  • Magnetic resonance tomographic angiography

    A technique that uses computer reconstruction of magnetic resonance angiography images to create images that display both vascular and other anatomic tissues simultaneously.

  • MAI

    Mycobacterium avium intracellular

  • Maintenance of Wakefulness Test

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of the ability to remain awake. Subjects are instructed to try to remain awake in a darkened room while in a semireclined position. Long latencies to sleep are indicative of the ability to remain awake. This test is most useful for assessing the effects of medication upon the ability to remain awake.

  • Maintenance of Wakefulness Test (MWT)

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of the ability to remain awake. Subjects are instructed to try to remain awake in a darkened room while in a semireclined position. Long latencies to sleep are indicative of the ability to remain awake. This test is most useful for assessing the effects of medication upon the ability to remain awake.

  • Major sleep episode

    The longest sleep episode that occurs on a daily basis. Typically the sleep episode dictated by the circadian rhythm of sleep and wakefulness; the conventional or habitual time for sleeping.

  • Major sleep episodes

    The longest sleep episode that occurs on a daily basis. Typically the sleep episode dictated by the circadian rhythm of sleep and wakefulness; the conventional or habitual time for sleeping.

  • MALDI

    Matrix-assisted laser desorption

  • malformation

    A morphologic abnormality that arises because of an abnormal developmental process. A primary error in morphogenesis—for example, cleft lip.

  • malformation sequence

    A pattern of multiple defects resulting from a single primary malformation--for example, talipes and hydrocephalus can result from a lumbar neural tube defect.

  • malformation syndrome

    A pattern of features, often with a unifying underlying cause, that arises from several different errors in morphogenesis (“syndrome” from the Greek “running together”).

  • MAM

    methylazoxymethanol

  • mAMPD

    muscle adenylic acid deaminase

  • Mann-Whitney U test

    This test is a non-parametric alternative to the unpaired t test and requires all the observations to be ranked as if they were from a single sample. The sum of the ranks in one group is calculated, and a p value is found from a table. The statistic U (number of all possible pairs of observations comprising one from each sample) is somewhat complicated, but it has the advantage that it is one of the few non-parametric tests that has a useful interpretation.

  • MAO

    monoamine oxidase

  • MAOI

    monoamine oxidase inhibitor

  • Marburg variant multiple sclerosis

    Part of the spectrum of multiple sclerosis initially described by Marburg in 1906, which included examples of lesions with bands of preserved myelin and disrupted myelin.

  • Marche a petits pas

    Lacunar gait-gait apraxia, with gait disturbance characterized by appearance of feet glued to the floor.

  • Marchiafava-Bignami syndrome

    Degeneration of the corpus callosum seen in individuals with alcoholism.

  • Markov chain Monte Carlo

    A class of algorithms for sampling from probability distributions based on constructing a Markov chain that has the desired distribution as its equilibrium distribution. Markov chain means that the description of the present state enables determination of future states through a probabilistic process. It is used in statistics to generate sequences of random numbers for depicting complicated desired probability distributions.

  • Maroteaux-Lamy syndrome

    Autosomal recessive mucopolysaccharidosis caused by arylsulfate beta deficiency, with dermatan sulfate excreted in the urine. Hurler-like symptoms are seen, with coarse facial features, dysotosis multiplex, short stature, corneal clouding, hepatosplenomegaly, hearing loss, and normal intelligence. Life span is dependent on extent of cardiomyopathy and valvular disease. Also known as mucopolysaccharidosis VI and arylsulfate beta deficiency.

  • MASA

    mental retardation, aphasia, shuffling gait, and adducted thumbs

  • MASA syndrome

    mental retardation, aphasia, shuffling gait, and adducted thumbs

  • MAST-E

    Multicentre Acute Stroke Trial-Europe

  • MAST-I

    Multicentre Acute Stroke Trial-Italy

  • Masticatory seizures

    Seizures with swallowing automatisms originating in the frontal operculum.

  • Maternal inheritance

    Inheritance from mother to child, characteristic of disorders due to abnormalities of the mitochondrial genome.

  • MATR3

    matrin3

  • MBP

    myelin basic protein

  • MCA

    middle cerebral artery

  • MCAD

    medium-chain acyl-CoA dehydrogenase

  • McLeod syndrome

    X-linked recessive illness with a similar clinical syndrome to neuroacanthocytosis. It is characterized by the lack of the Kx red cell antigen.

  • MCM

    L-methylmalonyl-coenzyme A mutase

  • MCT

    medium-chain triglyceride

  • MDD

    myoadenylate deaminase deficiency

  • MDGCR

    minimal DiGeorge critical region

  • MDMA

    methylenedioxymethamphetamine

  • MDS

    Miller-Dieker syndrome

  • MEB

    muscle, eye, and brain disease

  • MEG

    magnetoencephalography

  • Meige syndrome

    A combination of blepharospasm and oromandibular dystonia.

  • MELAS

    mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes syndrome

  • MEN1

    multiple endocrine neoplasia type 1

  • Meningoencephalitis

    Inflammatory disease of the meninges and brain.

  • MEPC

    miniature endplate current

  • MEPP

    miniature endplate potential

  • MERRF

    myoclonus epilepsy with ragged-red fibers

  • Mesial temporal lobe epilepsy

    A syndrome of temporal lobe epilepsy associated with hippocampal sclerosis, often surgically correctable.

  • Metachromatic leukodystrophy

    An autosomal recessive disorder on chromosome 22 resulting in a deficiency of arylsulfatase A. There is an accumulation of sulfatide in the central and peripheral nervous system, which causes progressive spastic quadriparesis after initial weakness and hypotonia, posturing, behavioral changes, gallstones, peripheral neuropathy, optic atrophy, and seizures. The onset can occur in late infancy, adolescence, or adulthood.

  • Methemoglobinemia

    A modified form of oxyhemoglobin found in the blood as adverse reaction to certain drugs.

  • Methionine synthase

    A vitamin B-12-dependent enzyme that catalyzes the synthesis of methionine from homocysteine and 5-methyltetrahydrofolate.

  • Metopic stenosis

    A condition in which there is premature fusion of the metopic suture, resulting in a triangular shaped forehead. A bony ridge extends from the bridge of the nose to the upper part of the forehead, producing a prominent midline keel with lateral recession of the brows. From the frontal view, these patients typically have the appearance of hypotelorism or decreased distance between the eyes. Also known as trigonocephaly.

  • MeV

    million electron volts

  • mfERG

    multifocal electroretinogram

  • MFG

    A retroviral vector

  • MGUS

    monoclonal gammopathy of unknown significance

  • MHA-TP

    microhemagglutination assay for antibody to Treponema pallidum

  • MHC

    major histocompatibility complex

  • MHPG

    3-methoxy-4-hydroxypheylglycol

  • MIB1-LI

    MIB1 labeling index

  • MIBG

    metaiodobenzylguanidine

  • MiBK

    methyl-isobutyl ketone

  • Michaelis constant

    The concentration of the substrate at which half the true maximum velocity of an enzyme-catalyzed reaction is achieved.

  • Michel deformity

    Labyrinthine aplasia

  • Mickey Mouse

    Atrophy of the mid-brain tegmentum with relative preservation of the tectum and cerebral peduncles seen on axial T1-MRI in progressive supranuclear palsy.

  • Mickey Mouse sign

    Atrophy of the mid-brain tegmentum with relative preservation of the tectum and cerebral peduncles seen on axial T1-MRI in progressive supranuclear palsy.

  • Micrognathia

    Small jaw

  • Microphthalmia

    Congenitally small globe

  • Microscopic polyangiitis

    Inflammation of small-sized arteries, arterioles, capillaries, and venules without granuloma formation, involving kidney, lung, skin, and peripheral nerve, with infrequent involvement of other organs.

  • Microsleep

    An episode lasting up to 30 seconds during which external stimuli are not perceived. The polysomnogram suddenly shifts from waking characteristics to sleep. Microsleeps are associated with excessive sleepiness and automatic behavior.

  • Micturition diary

    A record of the times, amounts, and nature of fluids taken in orally and excreted through urination, usually recorded for a week.

  • MIM

    Mendelian Inheritance in Man

  • Minicore myopathy

    A childhood myopathy beginning soon after birth, characterized by hypotonia usually following a benign, nonprogressive course with typical muscle biopsy changes demonstrated by defects in enzyme histochemistry and sarcomeres out of register by electron microscopy. The diagnosis of minicore myopathy should be suspected in patients with a rigid spine or rapidly progressive kyphoscoliosis in adolescence.

  • Minipolymyoclonus

    A form of multifocal myoclonus, characterized by small jerks in different locations.

  • MiRNA

    MicroRNAs (miRNAs), small and mostly non-coding RNA gene products, are molecules derived from larger segments of "precursor" RNA that are found in all diverse multicellular organisms. MiRNAs are 21-25 nucleotide transcripts that repress gene function through interactions with target mRNAs. Molecular diagnostic technologies have been used to study miRNA gene expression and implicate miRNAs in viral disease, neurodevelopment, and cancer. Apart from their diagnostic value, miRNAs are also being used for development of therapeutics.

  • Mitgehen

    A condition in which patients are extremely compliant and will assume changes in posture with only slight effort from an examiner.

  • MJD

    Machado-Joseph disease

  • MJD/SCA3

    Spinocerebellar ataxia type 3 (Machado-Joseph disease)

  • MKRN3

    makorin ring finger protein

  • ML II

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis II.

  • ML III

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis III.

  • ML IV

    Deficiency of a ganglioside-specific neuraminidase.

  • MMA

    methylmalonic acidemia

  • MMPI

    Minnesota Multiphasic Personality Inventory

  • MMSE

    Mini-Mental State Examination

  • MnBK

    methyl-n-butyl ketone

  • MND

    motor neuron degeneration

  • MNGIE

    mitochondrial neurogastrointestinal encephalomyopathy

  • Moderate hyperhomocysteinemia

    Fasting plasma total homocysteine concentration between 15 micromolars and 100 micromolars.

  • MOG

    myelin oligodendrocyte glycoprotein

  • Mondini deformity

    An incomplete partition of cochlea.

  • monoclonal antibody

    A monoclonal antibody (MAb) is an antibody made from a single clone (hybridoma) of white blood cells.

  • Monoclonal band

    Abnormal proteins produced in the body that appear as a single band on serum protein electrophoresis.

  • Monoclonal bands

    Abnormal proteins produced in the body that appear as a single band on serum protein electrophoresis.

  • Monoclonal gammopathy

    Excessive production of identical immunoglobulins derived from transformation of single B cell clones.

  • Mononeuritis multiplex

    Simultaneous or sequential involvement of many noncontiguous nerves by a pathological process.

  • MOPP

    mechlorethamine, Oncovin, procarbazine, prednisone

  • Morning glory

    A concavity due to focal atrophy of the lateral margin of the midbrain tegmentum seen on axial T2w-MRI in multiple system atrophy and progressive supranuclear palsy.

  • Morning glory sign

    A concavity due to focal atrophy of the lateral margin of the midbrain tegmentum seen on axial T2w-MRI in multiple system atrophy and progressive supranuclear palsy.

  • Morquio syndrome

    Two biochemically distinct but clinically similar autosomal recessive forms of mucopolysaccharidoses, with both keratan sulfate and chondroitin sulfate excreted in the urine. The enzymatic defects are of galactosamine-6-sulfate sulfatase and beta-galactosidase, respectively. Skeletal and nervous system defects include dwarfism, odontoid hypoplasia, mild corneal clouding, kyphosis, valvular heart disease, hearing loss, atlantoaxial subluxation, waddling gait, and normal intelligence. Also known as mucopolysaccharidosis IV.

  • Morquio syndrome A-B

    Two biochemically distinct but clinically similar autosomal recessive forms of mucopolysaccharidoses, with both keratan sulfate and chondroitin sulfate excreted in the urine. The enzymatic defects are of galactosamine-6-sulfate sulfatase and beta-galactosidase, respectively. Skeletal and nervous system defects include dwarfism, odontoid hypoplasia, mild corneal clouding, kyphosis, valvular heart disease, hearing loss, atlantoaxial subluxation, waddling gait, and normal intelligence. Also known as mucopolysaccharidosis IV.

  • Motor fluctuations

    The unpredictable motor response to levodopa in patients with chronic Parkinson disease.

  • Motor impersistence

    Failure to sustain voluntary muscular contraction to command for periods too brief to result from muscle fatigue.

  • Motor neglect

    Failure to mobilize a body part spontaneously, but with intact self-mobility when the patient is commanded to attend to or to move the part; must be distinguished from paralysis.

  • Motor tic

    Repetitive abrupt, sudden, brief isolated movements.

  • Motor tics

    Repetitive abrupt, sudden, brief isolated movements.

  • Movement arousal

    A body movement associated with an EEG pattern of arousal or a full awakening; a sleep scoring variable.

  • movement arousals

    A body movement associated with an EEG pattern of arousal or a full awakening; a sleep scoring variable.

  • Movement time

    The term used in sleep record scoring to denote when EEG and EOG tracings are obscured for more that half the scoring epoch because of movement. It is only scored when the preceding and subsequent epochs are in sleep.

  • MPA

    microscopic polyangiitis

  • MPO

    myeloperoxidase

  • MPP

    1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

  • MPS I-H

    An autosomal recessive mucopolysaccharide caused by deficiency of alpha-L-iduronidase. Characterized by excretion of dermatan sulfate and heparan sulfate in the urine. Onset is usually around 1 year with symptoms of progressive mental deterioration, gargoyle facies, kyphosis, dwarfism, dysotosis multiplex, hepatosplenomegaly, and cardiac defects. Death occurs by 10 years, usually by respiratory infection or heart failure. Also known as mucopolysaccharidosis I-H.

  • MPS I-H/S

    Intermediate autosomal recessive syndrome between mucopolysaccharidosis I-H and mucopolysaccharidosis I-S. Caused by deficiency of alpha-L-iduronidase. Symptoms consist of hearing loss, visual impairment, dysotosis multiplex pachymeningitis cervicalis, and little or no intellectual dysfunction. Also known as mucopolysaccharidosis I-H/S.

  • MPS I-S

    Relatively mild form of mucopolysaccharidosis I, with the characteristic autosomal recessive enzymatic defect of alpha-L-iduronidase. As with other mucopolysaccharidosis I syndromes dysotosis multiplex, joint abnormalities, corneal clouding, hearing loss, valvular disease, and obstructive airway disease are seen; but intelligence, stature, and life span are typically normal. Also known as mucopolysaccharidosis I-S, and previously as mucopolysaccharidosis V.

  • MPS III A-D

    Autosomal recessive biochemically distinct but clinically similar diseases. These syndromes are characterized by normal facial features and stature, absence of corneal clouding, mild hepatosplenomegaly, rapidly progressive mental retardation between 2 and 10 years, hearing loss, seizures, behavioral problems, and usually death before 20 years. Types A-D have enzymatic defects of N-sulfoglucosamine sulfohydrolase (heparan-N-sulfatase), N-alpha-acetylglucosaminidase (alpha-N-acetyl-lucosaminidase), heparin acetyl-CoA:alpha-glucosaminide N-acetyltransferase (acetyl-CoA:alpha-glucosaminide acetyltransferase), and N-acetylglucosamine-6-sulfatase (N-acetylglucosamine-beta-sulfatase), respectively, each causing excretion of heparan sulfate in the urine. Also referred to as mucopolysaccharidosis III A-D.

  • MPS VI

    Autosomal recessive mucopolysaccharidosis caused by arylsulfate beta deficiency, with dermatan sulfate excreted in the urine. Hurler-like symptoms are seen, with coarse facial features, dysotosis multiplex, short stature, corneal clouding, hepatosplenomegaly, hearing loss, and normal intelligence. Life span is dependent on extent of cardiomyopathy and valvular disease. Also known as mucopolysaccharidosis VI and arylsulfate beta deficiency.

  • MPTP

    1-methyl-4-phenyl-1,2,3,6-propionoxypiperidine

  • MRA

    magnetic resonance angiography

  • MRC

    medical research council

  • MRI

    magnetic resonance imaging

  • MRN

    magnetic resonance neurography

  • mRNA

    messenger ribonucleic acid

  • MRS

    magnetic resonance spectroscopy

  • MRTA

    A technique that uses computer reconstruction of magnetic resonance angiography images to create images that display both vascular and other anatomic tissues simultaneously.

  • MSA

    multiple system atrophy

  • MSLT

    multiple sleep latency test

  • MSUD

    maple syrup urine disease

  • MTCA

    mixed transcortical aphasia

  • mtDNA

    Mitochondrial deoxyribonucleic acid. Human mtDNA is a maternally inherited 16,569 base pair genome encoding 37 genes: 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes, and 13 genes coding for protein subunits of respiratory chain complexes I, III, IV, and V.

  • MTHFR

    methylene tetrahydrofolate reductase

  • MTLE

    mesial temporal lobe epilepsy

  • MTLE-HS

    mesial temporal lobe epilepsy associated with hippocampal sclerosis

  • MTM1

    myotubularin gene in Xq28

  • MTMX

    myotubular myopathy, X-linked

  • MTPT

    1-methyl-4-phenyl-1,2,3,6-tetrahydro pyridine

  • MTR

    magnetization transfer ration

  • MUAP

    motor unit action potential

  • MUAPs

    motor unit action potentials

  • mucolipidosis I

    Cherry-red spot myoclonus syndrome due to a primary neuraminidase defect. Type I is normosomatic; type II is dysmorphic. Also known as mucolipidosis I.

  • mucolipidosis II

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis II.

  • mucolipidosis III

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis III.

  • Mucolipidosis IV

    Deficiency of a ganglioside-specific neuraminidase.

  • Mucopolysaccharide

    Heteropolysaccharides usually containing two types of monosaccharide unit, of which one has an acidic group. They occur in complexes with specific proteins called mucins, or mucoproteins, to form glycoproteins, eg, dermatan sulfate, heparan sulfate, chondroitin sulfate.

  • Mucopolysaccharides

    Heteropolysaccharides usually containing two types of monosaccharide unit, of which one has an acidic group. They occur in complexes with specific proteins called mucins, or mucoproteins, to form glycoproteins, eg, dermatan sulfate, heparan sulfate, chondroitin sulfate.

  • mucopolysaccharidosis I-H

    An autosomal recessive mucopolysaccharide caused by deficiency of alpha-L-iduronidase. Characterized by excretion of dermatan sulfate and heparan sulfate in the urine. Onset is usually around 1 year with symptoms of progressive mental deterioration, gargoyle facies, kyphosis, dwarfism, dysotosis multiplex, hepatosplenomegaly, and cardiac defects. Death occurs by 10 years, usually by respiratory infection or heart failure. Also known as mucopolysaccharidosis I-H.

  • mucopolysaccharidosis I-H/S

    Intermediate autosomal recessive syndrome between mucopolysaccharidosis I-H and mucopolysaccharidosis I-S. Caused by deficiency of alpha-L-iduronidase. Symptoms consist of hearing loss, visual impairment, dysotosis multiplex pachymeningitis cervicalis, and little or no intellectual dysfunction. Also known as mucopolysaccharidosis I-H/S.

  • mucopolysaccharidosis I-S

    Relatively mild form of mucopolysaccharidosis I, with the characteristic autosomal recessive enzymatic defect of alpha-L-iduronidase. As with other mucopolysaccharidosis I syndromes dysotosis multiplex, joint abnormalities, corneal clouding, hearing loss, valvular disease, and obstructive airway disease are seen; but intelligence, stature, and life span are typically normal. Also known as mucopolysaccharidosis I-S, and previously as mucopolysaccharidosis V.

  • mucopolysaccharidosis III A-D

    Autosomal recessive biochemically distinct but clinically similar diseases. These syndromes are characterized by normal facial features and stature, absence of corneal clouding, mild hepatosplenomegaly, rapidly progressive mental retardation between 2 and 10 years, hearing loss, seizures, behavioral problems, and usually death before 20 years. Types A-D have enzymatic defects of N-sulfoglucosamine sulfohydrolase (heparan-N-sulfatase), N-alpha-acetylglucosaminidase (alpha-N-acetyl-lucosaminidase), heparin acetyl-CoA:alpha-glucosaminide N-acetyltransferase (acetyl-CoA:alpha-glucosaminide acetyltransferase), and N-acetylglucosamine-6-sulfatase (N-acetylglucosamine-beta-sulfatase), respectively, each causing excretion of heparan sulfate in the urine. Also referred to as mucopolysaccharidosis III A-D.

  • mucopolysaccharidosis IV

    Two biochemically distinct but clinically similar autosomal recessive forms of mucopolysaccharidoses, with both keratan sulfate and chondroitin sulfate excreted in the urine. The enzymatic defects are of galactosamine-6-sulfate sulfatase and beta-galactosidase, respectively. Skeletal and nervous system defects include dwarfism, odontoid hypoplasia, mild corneal clouding, kyphosis, valvular heart disease, hearing loss, atlantoaxial subluxation, waddling gait, and normal intelligence. Also known as mucopolysaccharidosis IV.

  • mucopolysaccharidosis IX

    A newly described deficiency of hyaluroglucosaminidase 1 for the major glycosaminoglycan hyaluronan. Previously thought to be incompatible with life, the primary areas of impact are joints (periarticular soft tissue masses, acetabular erosions) and short stature, with no apparent impact on cognitive neurodevelopment. The gene HYAL1 encodes a specific lysosomal hyaluronidase with 2 specific allele mutations having been indentified. The existence of 2 other genes, HYAL2 and HYAL3 would therefore predict the existence of other hyaluroglucosaminidase deficiency disorders.

  • mucopolysaccharidosis VI

    Autosomal recessive mucopolysaccharidosis caused by arylsulfate beta deficiency, with dermatan sulfate excreted in the urine. Hurler-like symptoms are seen, with coarse facial features, dysotosis multiplex, short stature, corneal clouding, hepatosplenomegaly, hearing loss, and normal intelligence. Life span is dependent on extent of cardiomyopathy and valvular disease. Also known as mucopolysaccharidosis VI and arylsulfate beta deficiency.

  • mucopolysaccharidosis VII

    Autosomal recessive mucopolysaccharidosis caused by a deficiency in beta-glucuronidase with heparan sulfate and chondroitin sulfate excreted in the urine. Hurler-like features are seen including dysotosis multiplex, hepatosplenomegaly, and short stature. Intelligence ranges from severely impaired to normal. Also known as mucopolysaccharidosis VII.

  • mulberry molar

    Notched molars.

  • Mulberry molars

    Notched molars.

  • Multi-infarct dementia

    Dementia due to cerebrovascular disease.

  • Multimodal

    Pertaining to more than one sensory modality.

  • Multiple sleep latency test

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of excessive sleepiness. Subjects are allowed a fixed number of opportunities to fall asleep during their customary awake period. Excessive sleepiness is characterized by short latencies. Long latencies are helpful in distinguishing physical tiredness or fatigue from true sleepiness.

  • Multiple sleep latency test (MSLT)

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of excessive sleepiness. Subjects are allowed a fixed number of opportunities to fall asleep during their customary awake period. Excessive sleepiness is characterized by short latencies. Long latencies are helpful in distinguishing physical tiredness or fatigue from true sleepiness.

  • multiple sleep latency tests

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of excessive sleepiness. Subjects are allowed a fixed number of opportunities to fall asleep during their customary awake period. Excessive sleepiness is characterized by short latencies. Long latencies are helpful in distinguishing physical tiredness or fatigue from true sleepiness.

  • Multiple sulfatase deficiency

    An autosomal recessive disorder with deficiency of arylsulfatases A, B, and C and several other sulfatases needed for sulfatide and mucopolysaccharide metabolism. Symptoms are those of severe metachromatic leukodystrophy with mucopolysaccharidosislike features. Psychomotor delay, coarse facial features, hepatosplenomegaly, bony abnormalities, and ichthyosis become apparent within the first 2 years of life.

  • MuSK

    muscle specific kinase

  • MWT

    A series of measurements of the interval from "lights out" to sleep onset that is utilized in the assessment of the ability to remain awake. Subjects are instructed to try to remain awake in a darkened room while in a semireclined position. Long latencies to sleep are indicative of the ability to remain awake. This test is most useful for assessing the effects of medication upon the ability to remain awake.

  • Myelin associated glycoprotein

    A minor protein constituent of peripheral nerve myelin.

  • Myelin protein zero

    Major membrane protein of peripheral nerve myelin that mediates adhesion and compaction between and within myelin lamellae and between myelin and the axon.

  • Myelinoclastic

    Causing destruction of myelin.

  • Myelitis

    Inflammatory disease of the spinal cord.

  • Myelopathy

    Spinal cord dysfunction.

  • Myoclonic status epilepticus

    A prolonged state of relentless spontaneous generalized or multifocal myoclonus of predominantly cortical origin. Myoclonic jerks must occur either (1) at least once every 10 seconds for longer than 10 minutes or (2) at least once a minute for longer than 30 minutes.

  • Myophosphorylase deficiency

    A disorder characterized by a gross failure of the breakdown of glycogen to lactic acid.

  • Myotactic unit

    A group of agonist and antagonist muscles, which function together as a unit because they share common spinal reflex responses.

  • Myotonic dystrophy

    A disease named for its principal manifestations in skeletal muscle: myotonia-the sustained contraction of muscle in response to electrical or percussive stimuli-and dystrophy-the progressive loss of skeletal muscle with fibrosis and fatty infiltration. It is inherited as an autosomal dominant trait with extremely variable penetrance. The most constant feature is the extreme variation of clinical expression between multiple members of each pedigree. The apparent worsening of the disease in subsequent generations, or anticipation, is characteristic. The occurrence of a congenital form of myotonic dystrophy, inherited by either sex but only through their mother, is another manifestation of the disease. With the discovery of the inherited variable trinucleotide repeat, some of these genetic phenomena are being explained, but the mysteries of myotonic dystrophy are still unfolding.

  • Myxedema

    Severe hypothyroidism associated with a doughy induration of the skin

  • N-linked glycosylation

    The process in which a lipid-linked oligosaccharide is preformed in the ER, transferred to target proteins (onto asparagines), and further modified whence protein-bound.

  • N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

    A contaminating byproduct of meperidine synthesis that can induce parkinsonism in human and nonhuman animals (as the result of dopaminergic neuronal cell death) when injected intravenously. The serendipitous discovery of this selectively neurotoxic compound has allowed development of animal models of parkinsonism.

  • N314D

    aspartate (D) substituted for asparagine (N) at codon 314 of the galactose-1-phosphate uridyltransferase complementary deoxyribonucleic acid

  • NAA

    N-acetylaspartic acid

  • NAD

    nicotinamide adenine dinucleotide

  • NADH

    reduced form of nicotinamide adenine dinucleotide

  • NADH-TR

    nicotinamide adenine dinucleotide dehydrogenase tetrazolium reductase

  • NADPH

    reduced form of nicotinamide adenine dinucleotide phosphate

  • NAGS

    N-acetylglutamate synthetase

  • NAION

    nonarteritic anterior ischemic optic neuropathy

  • NAIP

    neuronal apoptosis inhibitory protein

  • Nanoparticles

    Particulate matter on nanoscale, ie, at the level of atoms, molecules, and supramolecular structures. At least 1 characteristic dimension of these particles is measured in nanometers (a nanometer is one-billionth of a meter). Nanoparticles occur in nature and can also be created in the laboratory. Applications include molecular diagnostics, drug delivery, and therapeutics.

  • NARP

    Neurogenic weakness, ataxia, retinitis pigmentosa

  • NASBA

    nucleic acid sequence based amplification

  • NASCIS

    National Acute Spinal Cord Injury Study

  • Natriuresis

    Excretion of sodium in urine.

  • NBIA

    neurodegeneration with brain iron accumulation

  • NCI

    National Cancer Institute

  • NCL

    neuronal ceroid lipofuscinosis

  • NCOG

    Northern California Oncology Group

  • NCSE

    nonconvulsive status epilepticus

  • NCV

    nerve conduction velocity

  • NDN(NECDIN)

    neurally differentiated EC-cell derived factor

  • nDNA

    nuclear deoxyribonucleic acid

  • near-SIDS

    The apparent sudden and unexpected death of an infant, who then survives spontaneously or with medical help.

  • near-sudden infant death syndrome

    The apparent sudden and unexpected death of an infant, who then survives spontaneously or with medical help.

  • Neglect alexia

    Reading disorder characterized by failure to identify the initial or left-most portion of a string of letters or words in a text. Neglect ataxia corresponds to spatial alexia.

  • Negri bodies

    Characteristic viral inclusions in the cytoplasm of rabies virus-infected neurons.

  • negri body

    Characteristic viral inclusions in the cytoplasm of rabies virus-infected neurons.

  • Nemaline myopathy

    A congenital hereditary disorder of muscle that usually causes symptoms beginning in infancy or early childhood. Prominent features include facial diplegia, severe hypotonia, and generalized weakness that is often nonprogressive. Patients may die in infancy from respiratory failure or may survive into adulthood with moderate restrictive lung disease. The hallmark of the disorder is the histopathological appearance of "rods" in myofibers, usually intramyofibrillar but occasionally intranuclear, for which the pathogenesis remains unknown. Congenital muscle fiber-type disproportion or massive type I fiber predominance is an associated finding in the muscle biopsy.

  • neologism

    "Words" that previous to a cerebral injury did not exist in the patient's vocabulary or culture.

  • Neologisms

    "Words" that previous to a cerebral injury did not exist in the patient's vocabulary or culture.

  • neonatal seizure

    Refers to all seizure phenomena occurring in the neonatal period.

  • Neonatal seizures

    Refers to all seizure phenomena occurring in the neonatal period.

  • Neural crest

    Embryonic tissue formed in the dorsal midline of the neural tube during its closure, which later separates from the neural tube. The cells derived from the neural crest migrate bilaterally to different sites in the body.

  • neuralgia

    Pain in the distribution of a nerve or nerves.

  • Neurally-mediated syncope

    The common or "vasovagal" faint characterized as an apparent dissociation between the vasodepressor (vascular) and bradycardic (vagally-mediated) components.

  • Neurapraxia

    The mildest form of peripheral nerve injury that produces an incomplete and transient loss of function that spontaneously recovers within hours to months of injury.

  • neuritis

    Inflammation of a nerve or nerves.

  • Neurofibromin

    Protein product of gene on chromosome 17 which is defective in neurofibromatosis type 1.

  • Neuroleptic

    Antipsychotic agent.

  • Neuroma-in-continuity

    A peripheral nerve lesion in which the nerve itself remains grossly intact despite a variable amount of internal fascicular disruption.

  • Neuronal migration

    Implies the displacement (movement or migration) of newly generated neurons from their birthplaces around the ventricular cavity in the central nervous system where most neurons are generated from the primitive neuroepithelial germinal layer to their definitive destinations (eg, the cerebral cortex layers). This phenomenon of neuronal migration in the developing telencephalon is assisted by a system of primitive and immature glial cells known as radial glial fibers whose surfaces provide a guiding role to migrating neurons.

  • Neuropathic pain

    Pain typically resulting from damage to the peripheral nerve, the dorsal root ganglion, dorsal root, or the central nervous system.

  • New daily persistent headache

    Daily headache arising within a few days without a gradual increase in headache frequency.

  • NF1

    neurofibromatosis type 1

  • NF2

    neurofibromatosis type 2

  • NFLE

    nocturnal frontal lobe epilepsy

  • NGF

    nerve growth factor

  • NHANES

    National Health and Nutrition Examination Survey

  • NHL-CNS

    non-Hodgkin lymphoma-central nervous system

  • NIAID

    National Institute of Allergy and Infectious Disease

  • NICCD

    Neonatal intrahepatic cholestasis caused by citrin deficiency

  • NIHSS

    National Institute of Health Stroke Scale

  • Nil per ora

    Nothing by mouth

  • NINDS-AIREN

    Neuroepidemiology Branch of the National Institute of Neurological Diseases and Stroke (NINDS) and the Association Internationale pour la Recherche et L'Enseignement en Neurosciences (AIREN)

  • Ninjurin

    A nerve injury-induced protein

  • NIPA1

    non-imprinted in Prader-Willi/Angelman loci

  • NMDA

    N-methyl-D-aspartate

  • NMDAR

    N-methyl-D-aspartate receptor

  • NMR

    nuclear magnetic resonance

  • NNRTI

    non-nucleoside reverse transcriptase inhibitor

  • Noack syndrome

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • Noack's syndrome

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • nociception

    The neural process of encoding noxious stimuli.

  • nociceptive pain

    Pain that arises from actual or threatened damage to non-neural tissue and is due to the activation of nociceptors.

  • nociceptor

    A high-threshold sensory receptor of the peripheral somatosensory nervous system that is capable of transducing and encoding noxious stimuli.

  • Nocturnal confusion

    Episodes of delirium and disorientation close to or during nighttime sleep; often seen in the elderly, and is indicative of organic central nervous system deterioration.

  • Nocturnal dyspnea

    Respiratory distress that may be minimal during the day, but becomes quite pronounced during sleep.

  • Nocturnal penile tumescence

    The natural periodic cycle of penile erections that occur during sleep, typically associated with REM sleep. Preferred term: sleep-related erections.

  • Nocturnal penile tumescence (NPT)

    The natural periodic cycle of penile erections that occur during sleep, typically associated with REM sleep. Preferred term: sleep-related erections.

  • Nocturnal sleep

    Indicative of the typical "nighttime" or major sleep episode related to the circadian rhythm of sleep and wakefulness; the conventional or habitual time for sleeping.

  • Non-cyclic alternating pattern

    EEG translation of a sustained condition of sleep stability.

  • Noncommunicating hydrocephalus

    Hydrocephalus due to structural obstruction of CSF circulation within the ventricular system, eg, colloid cyst of the third ventricle.

  • Nonpenetrating head trauma

    Blunt injury that does not result in laceration of dura or penetration of the cerebral tissue.

  • Northern blot

    A standard method for analyzing the structure of DNA fragments. RNA is separated by electrophoresis, transferred to filters, and probed with complimentary sequences.

  • northern blot test

    A standard method for analyzing the structure of DNA fragments. RNA is separated by electrophoresis, transferred to filters, and probed with complimentary sequences.

  • northern blotting

    A standard method for analyzing the structure of DNA fragments. RNA is separated by electrophoresis, transferred to filters, and probed with complimentary sequences.

  • Notch3

    The gene on chromosome 19 that may be defective in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

  • noxious stimulus

    A stimulus that is damaging or threatens damage to normal tissues.

  • NPH

    normal-pressure hydrocephalus

  • NPSLE

    neuropsychiatric systemic lupus erythematosus

  • NPT

    The natural periodic cycle of penile erections that occur during sleep, typically associated with REM sleep. Preferred term: sleep-related erections.

  • NPV

    negative predictive value

  • NREM

    Non-rapid eye movement sleep state. The other major sleep state apart from REM sleep; comprises sleep stages 1-4, which constitute levels in the spectrum of NREM sleep "depth" or physiological intensity.

  • NREM sleep intrusion

    An interposition of NREM sleep, or a component of NREM sleep physiology (eg, elevated EMG, K complex, sleep spindle, delta waves), in REM sleep; a portion of NREM sleep not appearing in its usual sleep cycle position.

  • NREM sleep period

    The NREM sleep portion of NREM-REM sleep cycle; such an episode consists primarily of sleep stages 3 and 4 early in the night and of sleep stage 2 later.

  • NREM stage 1

    A stage of NREM sleep that occurs at sleep onset or that follows arousal from sleep stages 2, 3, 4, or REM. It consists of a relatively low-voltage EEG with mixed frequency, mainly theta activity and alpha activity of less than 50% of the scoring epoch. It contains EEG vertex waves and slow rolling eye movements; no sleep spindles, K complexes, or REMs. Stage 1 normally represents 4-5% of the major sleep episode.

  • NREM stage 2

    A stage of NREM sleep characterized by the presence of sleep spindles and K complexes present in a relatively low-voltage, mixed-frequency EEG background; high-voltage delta waves may comprise up to 20% of stage 2 epochs; usually accounts for 45-55% of the major sleep episode.

  • NREM stage 3

    A stage of NREM sleep defined by at least 20% and not more than 50% of the episode consisting of EEG waves less than 2 Hz and more than 75 'V (high-amplitude delta waves); a "delta" sleep stage; with stage 4, it constitutes "deep" NREM sleep, so-called slow wave sleep (SWS); often combined with stage 4 into NREM sleep stage 3/4 because of the lack of documented physiological differences between the two; appears usually only in the first third of the sleep episode; usually comprises 4-6% of total sleep time.

  • NREM stage 4

    All statements concerning NREM sleep stage 3 apply to stage 4 except that high-voltage, EEG slow waves persist 50% or more of the epoch; NREM sleep stage 4 usually represents 12-15% of total sleep time. Sleepwalking, sleep terrors, and confusional arousal episodes generally start in stage 4 or during arousals from this stage. See Sleep Stage 3.

  • NREM-REM sleep cycle

    A period during sleep composed of an NREM sleep episode and the subsequent REM sleep episode; each NREM-REM sleep couplet is equal to one cycle. Any NREM sleep stage suffices as the NREM sleep portion of a cycle. An adult sleep period of 6.5-8.5 hours generally consists of four to six cycles. The cycle duration increases from infancy to young adulthood.

  • NREM-REM sleep cycle (Synonymous with sleep cycle)

    A period during sleep composed of an NREM sleep episode and the subsequent REM sleep episode; each NREM-REM sleep couplet is equal to one cycle. Any NREM sleep stage suffices as the NREM sleep portion of a cycle. An adult sleep period of 6.5-8.5 hours generally consists of four to six cycles. The cycle duration increases from infancy to young adulthood.

  • NRTI

    nucleoside reverse transcriptase inhibitor

  • NSAID

    non-steroidal anti-inflammatory drug

  • NSD

    nominal standard dose

  • NT

    neurotrophin

  • NTF

    neurotrophic factor

  • Obesity-hypoventilation syndrome

    A term applied to obese individuals who hypoventilate during wakefulness. Because the term can apply to several different disorders, it is discouraged from use.

  • Obtundation

    A mild to moderate reduction on alertness, with increasing time spent in the sleep state.

  • Occipital plagiocephaly

    A rare condition in which there is premature unilateral or bilateral fusion of the lambdoid suture. Also known as occipital plagiocephaly.

  • OCD

    obsessive-compulsive disorder

  • Ochronosis

    A rare inherited disorder of metabolism, characterized by urine that turns black when exposed to air. Another characteristic is the development of arthritis in adulthood. Also known as ochronosis or homogentisic acid oxidase deficiency.

  • OCTN

    organic cation/carnitine transporter

  • Ocular apraxia

    Defects in visual explorations with preserved ability to move.

  • OD

    right eye

  • Odynophagia

    Pain on swallowing.

  • OGT

    N-butlydeoxynojirimycin

  • OI

    osteogenesis imperfecta

  • OIS

    orbital inflammatory syndrome

  • Oligemia

    Decreased amount of blood in the body.

  • oligoclonal band

    Immunogolublin G of different migratory properties demonstrated by protein electrophoresis of serum or CSF; bands contain identical antibodies produced by multiple clones.

  • Oligoclonal bands

    Immunogolublin G of different migratory properties demonstrated by protein electrophoresis of serum or CSF; bands contain identical antibodies produced by multiple clones.

  • Oligodendrocyte

    Brain cell that synthesizes myelin.

  • Oligodendrocyties

    Brain cell that synthesizes myelin.

  • oligonucleotide

    A polymer made of few nucleotides.

  • Oligonucleotides

    A polymer made of few nucleotides.

  • Oncogene

    Genes associated with neoplastic proliferation following a mutation or perturbation in their expression. Various examples include growth hormones, receptors, G proteins, protein kinases, transcription factors, and cyclins.

  • Oncogenes

    Genes associated with neoplastic proliferation following a mutation or perturbation in their expression. Various examples include growth hormones, receptors, G proteins, protein kinases, transcription factors, and cyclins.

  • onion bulb

    Concentric layers of proliferating Schwann cells, surrounding the axons of affected nerve fibers. Onion bulbs result from repeated cycles of demyelination and remyelination.

  • Onion bulbs

    Concentric layers of proliferating Schwann cells, surrounding the axons of affected nerve fibers. Onion bulbs result from repeated cycles of demyelination and remyelination.

  • OPCA

    olivopontocerebellar atrophy

  • Open-label

    A type of clinical trial in which both the investigator and the patient know the identity of the medication.

  • Ophthalmoplegia

    The partial or complete inability to move the eye.

  • Oppositional defiant disorder

    Negativistic, hostile, and defiant behavior typified by interpersonal problems involving stubborn, resistant behavior, arguing and testing of limits, not following directions, and verbal aggression.

  • Optic atrophy

    Loss of optic nerve axons, usually resulting in a characteristic pallor of the optic disk.

  • Optic neuritis

    Inflammation of the optic nerves and chiasm, characterized by demyelination.

  • Optode

    Miniaturized fiberoptic electrodes that enable the continuous measurement of oxygen, carbon dioxide, and hydrogen ion.

  • optodes

    Miniaturized fiberoptic electrodes that enable the continuous measurement of oxygen, carbon dioxide, and hydrogen ion.

  • Oral-facial-digital syndrome

    A genetically and phenotypically heterogenous group of congenital disorders characterized by malformations of the mouth, face, and digits. Typical non-neuroanatomic manifestations include hypertrophic frenula, lingual hamartomas, cleft palate or lip, ocular hypertelorism, brachydactyly, polydactyly, and syndactyly. Associated malformations of the central nervous system are frequently present and psychomotor retardation is common. Porencephaly, hydrocephaly, ependymal cysts, hypothalamic hamartoma, heterotopic neuroglial rests, agenesis of the corpus callosum, cerebellar dysgenesis, and chorioretinal coloboma have been observed in patients with this condition. At least two genetic subtypes distinguished by X-linked dominant and autosomal recessive inheritance have been described, but significant phenotypic overlap exists between the two forms. Prognosis is highly variable and depends on the extent and severity of malformations. Patients with normal intelligence have been reported.

  • Oral-facial-digital syndromes

    A genetically and phenotypically heterogenous group of congenital disorders characterized by malformations of the mouth, face, and digits. Typical non-neuroanatomic manifestations include hypertrophic frenula, lingual hamartomas, cleft palate or lip, ocular hypertelorism, brachydactyly, polydactyly, and syndactyly. Associated malformations of the central nervous system are frequently present and psychomotor retardation is common. Porencephaly, hydrocephaly, ependymal cysts, hypothalamic hamartoma, heterotopic neuroglial rests, agenesis of the corpus callosum, cerebellar dysgenesis, and chorioretinal coloboma have been observed in patients with this condition. At least two genetic subtypes distinguished by X-linked dominant and autosomal recessive inheritance have been described, but significant phenotypic overlap exists between the two forms. Prognosis is highly variable and depends on the extent and severity of malformations. Patients with normal intelligence have been reported.

  • Organomegaly

    Enlargement of certain organs in the body.

  • Oromandibular dystonia

    Dystonia involving the jaw, mouth, tongue, and other lower facial muscles.

  • Orthodromic

    Conducting impulses in the normal direction.

  • OS

    left eye

  • OSA

    obstructive sleep apnea

  • OSAS

    obstructive sleep apnea syndrome

  • Oscillopsia

    An optical illusion of motion of a visually fixated target, due to movement of the image across the retina.

  • Osteosclerotic myeloma

    A neoplastic disease of the plasma cell in the bone marrow that causes sclerosis of the bone.

  • OTC

    ornithine transcarbamylase

  • Otolithic crisis or otolithic catastrophe of Tumarkin

    Drop attack without warning, associated autonomic or neurologic symptoms, loss of consciousness, or post-ictal signs in patient with severe vestibular disease, usually due to Meniere disease.

  • Oxidative phosphorylation

    The process by which ATP is formed as electrons are transferred from NADH or FADH2 to molecular oxygen (O2).

  • OXPHOS

    oxidative phosphorylation

  • Oxycephaly

    A congenital abnormality of the skull in which the top of the head assumes a conical or pointed shape because of premature closing of the lambdoid and coronal sutures. Also known as acrocephaly.

  • P value

    Probability value

  • P-value

    Probability value

  • P0

    protein zero

  • Pachygyria

    Gyral pattern consisting of few, unusually thick gyri.

  • PACNS

    primary angiitis of the central nervous system

  • PACO2

    arterial partial pressure of carbon dioxide

  • PADP

    pulmonary artery diastolic pressure

  • PAHX

    phytanoyl-CoA alpha hydroxylase

  • PALA

    N-(phosphonacetyl)-L-aspartate

  • Palatal myoclonus

    Involves the soft palate, and may be irritating, cause dysphagia, and even result in an audible clicking sound.

  • Palatal myoclonus (Palatal tremor)

    Involves the soft palate, and may be irritating, cause dysphagia, and even result in an audible clicking sound.

  • Palatal tremor

    Involves the soft palate, and may be irritating, cause dysphagia, and even result in an audible clicking sound.

  • Palilalia

    A condition in which a phrase or word is repeated with increasing rapidity.

  • Palinopsia

    Visual perseveration or the recurrent appearance of a visual image after the stimulus has disappeared.

  • Pallidotomy

    A procedure in which a lesion is made in the globus pallidus, most typically in the posteroventral portion of the internal globus pallidus.

  • PALP

    placental alkaline phosphatase

  • PANDAS

    Tics, obsessive-compulsive behavior and other neuropsychiatric abnormalities that presumably result from autoimmune attack triggered by infection with b-hemolytic group A streptococcus and targeted at basal ganglia neurons.

  • Panhypopituitarism

    Inadequate secretion of all pituitary hormones.

  • PAO2

    arterial partial pressure of oxygen

  • Papilledema

    Optic disc edema secondary to elevated intracranial pressure.

  • paradoxical insomnia

    A disorder in which a complaint of insomnia occurs without objective evidence of sleep disturbance.

  • Paradoxical sleep

    Synonymous with REM sleep, which is the preferred term.

  • Parafalcine subdural empyema

    A subdural empyema located between the medial surface of the cerebral hemisphere and the flax cerebri

  • Paragraphia

    Error in writing letters (literal paragraphia) and words (verbal paragraphia).

  • Paralexia

    A reading error consisting of a sound (phonemic or literal paralexia) or word (verbal paralexia) substitution.

  • Paralytic rabies

    Clinical form of rabies with early and prominent limb weakness.

  • Paramxyovirus

    Negative-strand, enveloped RNA virus.

  • Paraneoplastic

    Associated with a distant tumor relevant to the generation or perpetuation of the immune response.

  • Paraphasic

    Pertaining to abnormal speech distinguished by impaired sound or word selection.

  • Paratonia

    Active resistance of any effort to examine or move a patient.

  • Paresthesia

    Abnormal sensation, such as burning, prickling, or formication, that is not typically painful.

  • paresthesias

    Abnormal sensation, such as burning, prickling, or formication, that is not typically painful.

  • Paroxysmal nocturnal dyspnea

    Respiratory distress and shortness of breath due to pulmonary edema, which appears suddenly and often awakens the sleeping individual.

  • Paroxysmal nocturnal dyspnea (PND)

    Respiratory distress and shortness of breath due to pulmonary edema, which appears suddenly and often awakens the sleeping individual.

  • Partial seizure

    Clinical manifestation of a sudden, excessive, rapid, and localized electrical discharge by gray matter from a particular part of the brain. Consciousness may be intact ("simple partial") or impaired ("complex partial") during a partial seizure.

  • PAS

    periodic acid-Schiff

  • PCA-1

    Purkinje cell cytoplasmic antibody type 1

  • PCA2

    Purkinje cell antibody 2

  • PCD

    paraneoplastic cerebellar degeneration

  • PCH

    pontocerebellar hypoplasia

  • PCNA

    proliferating cell nuclear antigen

  • PCNSL

    primary central nervous system lymphoma

  • PCNU

    1-(2-chloroethyl)-3(2,6-dioxo-3-piperidyl)-1-nitrosourea

  • pCO2

    partial pressure of carbon dioxide

  • PCP

    phencyclidine

  • PCR

    polymerase chain reaction

  • PCV

    procarbazine, CCNU (lomustine), vincristine

  • PCWP

    pulmonary capillary wedge pressure

  • PDALS

    parkinsonism-dementia-amyotrophic lateral sclerosis

  • PDC

    parkinsonism dementia complex

  • PDD

    pervasive developmental disorder

  • PDE4D

    phosphodiesterase 4D gene

  • PDGF

    platelet-derived growth factor

  • PDGFR

    Platelet-derived growth factor receptor

  • PDHC

    pyruvate dehydrogenase complex

  • PDZ

    post synaptic density protein (PSD95), Drosophila disc large tumor suppressor (DlgA), and zo-1

  • PEDF

    pigment epithelium-derived factor

  • Peduncular hallucinosis

    A form of release phenomena with vivid, usually colored visual images possessing all the qualities of true sensoral perception. The patients correctly identify the hallucinations and are aware of their unreality, unlike with true visual hallucinations.

  • PEHO

    progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy

  • Pelizaeus-Merzbacher-like disease

    Patients with clinical and imaging criteria compatible with Pelizaeus-Merzbacher disease, but without a mutation found in the proteolipid gene.

  • Pellagra

    A disorder secondary to deficiency of nicotinic acid or tryptophan.

  • Pencil-shaped necrosis of the spinal cord

    Infarction of the ventral part of the dorsal column or dorsal horn that extends over several adjacent segments of the spinal cord.

  • Pendred syndrome

    A syndromic form of autosomal recessive hearing loss with goiter and a partial defect in iodide organification, which is due to balletic mutations in the SLC26A4 gene on chromosome 7q. The SLC26A4 gene encodes pendrin, a multifunctional anion exchanger. Pendred syndrome is often associated with forms of otic capsule dysplasia, including Mondini deformity and large vestibular aqueduct syndrome.

  • Penetrating head trauma

    An injury that results in disruption of the dura or underlying cerebral tissue.

  • Penguin

    Atrophy of the mid-brain tegmentum with relative preservation of the pons seen on mid-sagittal T1-MRI in progressive supranuclear palsy

  • Penguin sign

    Atrophy of the mid-brain tegmentum with relative preservation of the pons seen on mid-sagittal T1-MRI in progressive supranuclear palsy

  • Penile buckling pressure

    The amount of force applied to the glans of the penis sufficient to produce at least a 30 degree bend in the shaft.

  • Penile rigidity

    The firmness of the penis as measured by the penile buckling pressure. Normally, the fully erect penis has maximum rigidity.

  • Penile tumescence

    Hardening and expansion of the penis (penile erection). When associated with REM sleep, it is referred to as a sleep-related erection.

  • Penumbra

    Area surrounding an infarction in which blood flow is compromised but still present.

  • PEO

    progressive external ophthalmoplegia

  • PEP

    plasma cell dyscrasia, edema, and skin pigmentation

  • Periodic Leg Movements Index

    The number of periodic leg movements per hour of total sleep time as determined by all-night polysomnography. Sometimes expressed as the number of movements per hour of NREM sleep because the movements are usually inhibited during REM sleep. See Periodic Leg Movement.

  • Periodic Leg Movements Percentage

    The percentage of total sleep time occupied with recurrent episodes of periodic leg movements.

  • Periodic Limb Movements Index

    The number of periodic leg movements per hour of total sleep time as determined by all-night polysomnography. Sometimes expressed as the number of movements per hour of NREM sleep because the movements are usually inhibited during REM sleep. See Periodic Leg Movement.

  • Periodic Limb Movements Percentage

    The percentage of total sleep time occupied with recurrent episodes of periodic leg movements.

  • Peripheral alexia

    Reading disorder caused by visual processing deficits in which visual inputs cannot be associated with the stored representations of written words.

  • PERM

    Progressive encephalomyelitis with rigidity and myoclonus

  • Peroneal neuropathies

    A disorder characterized by selective dysfunction of the peroneal nerve(s) due to axonal loss or segmental demyelination or both.

  • Peroneal neuropathy

    A disorder characterized by selective dysfunction of the peroneal nerve(s) due to axonal loss or segmental demyelination or both.

  • Peroxisome

    Subcellular organelle, present in all cell types except erythrocytes, containing many oxidative enzymes and pathways important for normal lipid metabolism.

  • Peroxisomes

    Subcellular organelle, present in all cell types except erythrocytes, containing many oxidative enzymes and pathways important for normal lipid metabolism.

  • Perseveration

    Persistence of the same response, even when it is shown to be inappropriate.

  • Pfeiffer syndrome

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • Pfeiffer's syndrome

    A very rare genetic disorder characterized by abnormalities of the craniofacial area, distinctive malformations of the fingers and toes, and additional physical abnormalities. Also known as Pfeiffer syndrome, this disorder is generally accepted to be the same disorder as Noack Syndrome (Acrocephalopolysyndactyly Type I). The Acrocephalosyndactyly disorders are a group of very rare genetic disorders characterized by premature closure of the cranial sutures between certain bones of the skull, causing the top of the head to appear abnormally pointed, and webbing or fusion of certain fingers and/or toes.

  • PFK

    phosphofructokinase

  • PFK-M

    phosphofructokinase, muscle type

  • PGD

    preimplantation genetic diagnosis

  • PGM1

    phosphoglucomutase 1

  • pH

    potential hydrogen

  • Phakomatosis

    A group of hereditary diseases characterized by hamartomatous lesions in various tissues.

  • Phase activity

    Brain, muscle, or autonomic events of a brief and episodic nature occurring in sleep; characteristic of REM sleep, such as eye movements, or muscle twitches; usually the duration is milliseconds to 1-2 seconds.

  • Phase advance

    The shift of an episode of sleep or wake to an earlier position in the 24-hour sleep-wake cycle. A shift of sleep from 11 p.m.-7 a.m. to 8 p.m.-4 a.m. represents a 3-hour phase advance. See Phase Delay.

  • phase advances

    The shift of an episode of sleep or wake to an earlier position in the 24-hour sleep-wake cycle. A shift of sleep from 11 p.m.-7 a.m. to 8 p.m.-4 a.m. represents a 3-hour phase advance. See Phase Delay.

  • Phase delay

    A shift of an episode of sleep or wake to a later time of the 24-hour sleep-wake cycle. It is the exact opposite of phase advance. These terms differ from common concepts of change in clock time: to effect a phase delay, the clock is moved ahead or advanced. In contrast, to effect a phase advance, the clock moves backward. See Phase Advance.

  • phase delays

    A shift of an episode of sleep or wake to a later time of the 24-hour sleep-wake cycle. It is the exact opposite of phase advance. These terms differ from common concepts of change in clock time: to effect a phase delay, the clock is moved ahead or advanced. In contrast, to effect a phase advance, the clock moves backward. See Phase Advance.

  • Phase event

    Brain, muscle, or autonomic events of a brief and episodic nature occurring in sleep; characteristic of REM sleep, such as eye movements, or muscle twitches; usually the duration is milliseconds to 1-2 seconds.

  • phase shifts

    Change of a phase relative to a fixed external rhythm (clock time), eg, phase-delay, phase-advance.

  • Phase transition

    One of the two junctures of the major sleep and wake phases in the 24-hour sleep-wake cycle.

  • Phase-shift

    Change of a phase relative to a fixed external rhythm (clock time), eg, phase-delay, phase-advance.

  • Phasic event

    Brain, muscle, or autonomic events of a brief and episodic nature occurring in sleep; characteristic of REM sleep, such as eye movements, or muscle twitches; usually the duration is milliseconds to 1-2 seconds.

  • Phe

    phenylalanine

  • Phoneme

    A unit of word sound, roughly corresponding to a syllable.

  • Phonophobia

    Intolerance of noise.

  • Photoperiod

    The duration of light in a light-dark cycle.

  • Photopsia

    Simple visual disturbance, usually a sensation of flashing light.

  • Photosensitive epilepsy

    Epileptic syndrome characterized by generalized seizures induced by flickering or other changes in light stimulation.

  • Phthisis bulbi

    Shrinkage and wasting of globe.

  • PHYH

    phytanoyl-CoA alpha hydroxylase

  • Phytanic acid

    A branched-chain 20-carbon fatty acid, 3,7,11,15-tetramethylhexadecanoic acid, which is of exogenous (ie, dietary) origin in man and cannot be degraded by beta-oxidation.

  • Pi

    inorganic phosphate

  • Pick disease

    Dementing disorder associated with predominately frontal and/or temporal lobe atrophy with involvement of both gray and white matter.

  • Pick's disease

    Dementing disorder associated with predominately frontal and/or temporal lobe atrophy with involvement of both gray and white matter.

  • Pickwickian

    A term applied to an individual who snores, is obese and sleepy, and has alveolar hypoventilation. The term has been applied to many different disorders and therefore its use is discouraged.

  • Pili torti

    Twisted hairs.

  • Pilus

    A hairlike appendage found on the surface of many bacteria.

  • Pit-1

    A nuclear binding transcriptional factor found in many cells in human pituitary glands.

  • Pituitary agenesis

    Complete absence of all types of hypophyseal tissues.

  • Pituitary hypoplasia

    A pituitary gland of less than normal size located in a normal sella turcica.

  • PKCγ

    protein kinase gamma

  • PKU

    phenylketonuria

  • Plagiocephaly

    The coronal suture closes early and restricts growth of the forehead on the "synostosed" side. This leads to a flattening of the forehead and a "compensatory" bulging of the forehead on the opposite side. Also known as plagiocephaly.

  • Plasmacytoma

    Localized disease of plasma cells that commonly produce monoclonal bands.

  • Plasmapheresis

    The removal of plasma and replacement with saline or other plasma substitute.

  • Plasmin

    A fibrinolytic enzyme formed by plasminogen cleavage. Plasmin acts to cleave fibrin clots.

  • Platypnea-orthodeoxia syndrome

    Rare condition characterized by both dyspnea and arterial desaturation in the upright position-platypnea, with improvement in the supine position-orthodexia. It is seen in patent foramen ovale, atrial septal defect, pericardial effusion, constrictive pericarditis, emphysema, amiodarone pulmonary toxicity, pneumonectomy, and cirrhosis.

  • Platyspondylia

    Congenital flattening of the vertebral bones.

  • PLED

    periodic lateralizing epileptiform discharge

  • PLM index

    The number of periodic leg movements per hour of total sleep time as determined by all-night polysomnography. Sometimes expressed as the number of movements per hour of NREM sleep because the movements are usually inhibited during REM sleep. See Periodic Leg Movement.

  • PLM percentage

    The percentage of total sleep time occupied with recurrent episodes of periodic leg movements.

  • PLM-arousal index

    The number of sleep-related periodic leg movements per hour of sleep that are associated with an EEG arousal. See Periodic Leg Movement.

  • PLMS

    periodic leg movements of sleep

  • PLP

    proteolipid protein

  • PMC

    paramyotonia congenita

  • PML

    progressive multifocal leukoencephalopathy

  • PMLD

    Patients with clinical and imaging criteria compatible with Pelizaeus-Merzbacher disease, but without a mutation found in the proteolipid gene.

  • PMM2

    phosphomannomutase 2

  • PMP-22

    peripheral myelin protein 22 kd

  • PMP22

    A major membrane protein of peripheral nerve myelin that mediated adhesion and compaction between and within myelin lamellae and between myelin and the axon.

  • PNA

    peptide nucleic acid

  • PND

    Respiratory distress and shortness of breath due to pulmonary edema, which appears suddenly and often awakens the sleeping individual.

  • PNET

    primitive neuroectodermal tumor

  • PO2

    partial pressure of oxygen

  • POEMS

    polyneuropathy, organomegaly, endocrinopathy, monoclonal bands, skin changes

  • POLG

    Mitochondrial DNA polymerase gamma

  • Poliosis

    Gray/white hair

  • Polydactyly

    More than five digits on a hand or foot.

  • Polymicrogyria

    A malformation of the cortex attributed to a variety of pathological conditions disturbing normal neuronal migration.

  • Polymorphism

    Naturally-occurring genetic variations in the gene sequence. These can be single nucleotide polymorphisms or point mutations.

  • Polymorphisms

    Naturally-occurring genetic variations in the gene sequence. These can be single nucleotide polymorphisms or point mutations.

  • Polyneuropathy

    A disorder affecting peripheral nerves in a symmetric fashion.

  • Polyradiculoneuropathy

    Disorder involving spinal roots.

  • Polysomnogram

    The continuous and simultaneous recording of multiple physiological variables during sleep, ie, EEG, EOG, EMG (these are the three basic stage scoring parameters), EKG, respiratory air flow, respiratory movements, leg movements, and other electrophysiological variables.

  • Polysomnograph

    A biomedical instrument for the measurement of physiological variables of sleep.

  • Polysomnographic

    Describes a recording on paper, computer disc, or tape of a polysomnogram.

  • Polysomnographic (as in -Recording, -Monitoring, -Registration, or -Tracings)

    Describes a recording on paper, computer disc, or tape of a polysomnogram.

  • PON1

    paraoxonase/arylesterase 1 gene

  • Postencephalitic parkinsonism

    Motor syndrome characterized by a variable combination of rigidity, bradykinesia, tremor, oculogyric crisis and behavioral abnormalities following encephalitis.

  • Posterior cortical atrophy

    Progressive visual agnosia, alexia, Balint and Gerstmann syndrome, and transcortical sensory aphasia, which eventually develops into a dementia of the Alzheimer type.

  • Posterior fossa subdural empyema

    A subdural empyema located in the posterior fossa.

  • Posteroventral pallidotomy

    A procedure in which a lesion is made in the posteroventral globus pallidum, medial pallidum, or internal segment of the globus pallidus.

  • Posttraumatic stress disorder

    Posttraumatic stress disorder includes fearful awakenings from realistic dreams that repeat the trauma and may occur from stage 2 sleep or REM sleep earlier in the night.

  • POTS

    postural orthostatic tachycardia syndrome

  • Pott disease

    Extrapulmonary tuberculosis affecting the spine.

  • Pott's disease

    Extrapulmonary tuberculosis affecting the spine.

  • PPD

    purified protein derivative

  • PPMS

    primary progressive multiple sclerosis

  • PPOKS

    progressive postoperative kyphoscoliosis

  • PPP2R2B

    protein phosphatase 2A

  • PPRF

    parapontine reticular formation

  • PPV

    positive predictive value

  • PR

    partial response

  • PR3

    proteinase 3

  • Premature morning awakening

    Early termination of the sleep episode, with inability to return to sleep, sometimes after the last of several awakenings. It reflects interference at the end rather than at the commencement of the sleep episode. A characteristic sleep disturbance of some people with depression.

  • premature morning awakenings

    Early termination of the sleep episode, with inability to return to sleep, sometimes after the last of several awakenings. It reflects interference at the end rather than at the commencement of the sleep episode. A characteristic sleep disturbance of some people with depression.

  • PRES

    posterior reversible encephalopathy syndrome

  • Pressure waves

    Abnormal CSF pressure fluctuations seen in patients with increased cerebrospinal fluid pressure. Three types have been described, the most dramatic of which are plateau waves. These elevations of CSF pressure may be asymptomatic or associated with increased headache, tone, restlessness, nausea, vomiting, and impaired consciousness.

  • Pretectal area

    The area located anterior to the tectum mesencephali.

  • Primary dystonia

    Dystonia of unknown origin.

  • Primary hyperparathyroidism

    A disorder of bone and mineral metabolism due to excessive, abnormally regulated secretion of parathyroid hormone occurring in the absence of any physiologic stimulus extrinsic to the parathyroid glands.

  • Primary insomnia

    In the International Classification of Sleep Disorders, this is a synonym for idiopathic insomnia. In DSM-IV, primary insomnia is a much broader term, including idiopathic insomnia, psychophysiologic insomnia, and sleep state misperception syndrome.

  • Primary myoclonic status epilepsy

    Myoclonic status epilepticus that occurs in patients with primary generalized epilepsies.

  • prion disease

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • prion diseases

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • PRL

    prolactin

  • PROACT

    prolyse in acute cerebral thromboembolism

  • Procedural memory

    Memory processes that operate outside of conscious awareness. Learning is reflected in improved performance even though the person may not be aware of the performance improvement. Types of procedural memory include priming and motor learning. Another term for procedural memory is non-declarative memory.

  • progeria

    Extremely rapid aging from unknown etiology with death within the first decade.

  • Progeria (Hutchinson-Gilford syndrome)

    Extremely rapid aging from unknown etiology with death within the first decade.

  • PROMM

    proximal myotonic myopahty

  • propionic acidemia

    An inherited disorder of organic acidemia that is characterized by neurologic symptoms, ketolactic acidosis, and hyperammonemia (also called propionic acidemia).

  • propionicacidemia

    An inherited disorder of organic acidemia that is characterized by neurologic symptoms, ketolactic acidosis, and hyperammonemia (also called propionic acidemia).

  • Propionyl-CoA carboxylase deficiency

    An inherited disorder of organic acidemia that is characterized by neurologic symptoms, ketolactic acidosis, and hyperammonemia (also called propionic acidemia).

  • Proposed sleep disorder

    A disorder in which there is insufficient information available in the medical literature to confirm the unequivocal existence of the disorder. A category of the International Classification of Sleep Disorders.

  • proposed sleep disorders

    A disorder in which there is insufficient information available in the medical literature to confirm the unequivocal existence of the disorder. A category of the International Classification of Sleep Disorders.

  • Proprioceptive-induced seizures

    Epileptic syndrome characterized by brief tonic or simple partial seizures induced by active or passive movement.

  • Prosencephalon

    Anterior-most part of embryologic brain; differentiates into telecephalon and diencephalon.

  • Prosopagnosia

    A form of visual agnosia characterized by the inability to recognize familiar faces.

  • Protein C deficiency

    A hypercoagulable state caused by inherited deficiency of protein C.

  • Protein S deficiency

    A hypercoagulable state caused by inherited deficiency of protein S.

  • Proteoglycans

    Multifunctional macromolecules composed of a core polypeptide and a variable number of glycosaminoglycan chains.

  • PrP

    prion protein

  • Pseudo-Hurler polydystrophy

    Lysosomal enzyme deficiency resulting from a defective posttranslational modification. Also known as mucolipidosis III.

  • Pseudoarylsulfatase A deficiency

    A benign condition with abnormal arylsulfatase A activity by assay, but without symptoms of metachromatic leukodystrophy. Conversion of sulfatides to inorganic sulfates is found to be normal after sulfatide loading, rather than increased as in metachromatic leukodystrophy.

  • Pseudobulbar palsy

    Emotional lability, explosive laughing, and crying.

  • Pseudodementia

    Cognitive impairment resulting from depression that is characterized by lack of effort and overestimation of deficits. It is reversible with appropriate treatment of the depression. Also known as dementia syndrome of depression.

  • Pseudohypoparathyroidism

    A genetic disorder that resembles hypoparathyroidism (lowered levels of parathyroid hormone) but is caused by a lack of response to parathyroid hormone rather than a deficiency in the hormone itself. Also known as Albright hereditary osteodystrophy.

  • Pseudologia fantastica

    A clinical condition of outrageous lying.

  • Pseudoptosis

    A condition resembling an inability to lift the eyelid.

  • PSG

    progressive subcortical gliosis

  • Pshychophysiological insomnia

    a disorder so somatized tension and learned sleep-preventing associations that results in a complaint of insomnia and associated decreased functioning during wakefulness.

  • PSPRS

    Progressive Supranuclear Palsy Rating Scale

  • Psychoeducation

    Form of psychiatric treatment in which the psychiatrist offers precise information about the disease, its etiology, treatment, risk factors, and other relevant topics regarding the mental illness. It is mostly performed in a group, sometimes with relatives, and constitutes an effective strategy to improve the patient's insight, knowledge, compliance, and adherence to medication, thereby improving coping strategies and prognosis.

  • psychogenic seizure

    Involuntary intermittent events that resemble epileptic seizures but are psychologically induced.

  • Psychogenic seizures

    Involuntary intermittent events that resemble epileptic seizures but are psychologically induced.

  • Pterin-4a-carbinolamine dehydratase deficiency

    An autosomal recessive disorder of tetrahydrobiopterin metabolism resulting in mild hyperphenylalaninemia without affects on biogenic amine metabolism in the central nervous system. In pterin-4a-carbinolamine dehydratase deficiency, an additional peak of 7-biopterin (as opposed to the normal 6-biopterin) is detected, and minor signs consisting of slight tremors of upper limbs and hypertonia or hypotonia have been reported in the neonatal period.

  • PTS

    posttraumatic syndrome

  • PTSD

    Posttraumatic stress disorder includes fearful awakenings from realistic dreams that repeat the trauma and may occur from stage 2 sleep or REM sleep earlier in the night.

  • PTT

    partial thromboplastin time

  • Purpura

    Bleeding into the skin.

  • Purpura fulminan

    A fulminating form of purpura typically associated with infection, which occurs in children, and is associated with hypotension, fever, and disseminated intravascular coagulation.

  • Purpura fulminans

    A fulminating form of purpura typically associated with infection, which occurs in children, and is associated with hypotension, fever, and disseminated intravascular coagulation.

  • Putamen

    The larger and more lateral section of the lentiform nucleus.

  • PVL

    periventricular leukomalacia

  • PVRI

    pulmonary vascular resistance index

  • Q188R

    arginine (R) substituted for glutamine (Q) at codon 188 of the galactose-1-phosphate uridyltransferase complementary deoxyribonucleic acid

  • QRS

    Q wave, R wave, and S wave

  • QT

    blood volume (quantity) per unit of time

  • QTc

    cardiac output interval corrected for heart rate

  • Racemase

    Alpha-methylacyl-CoA racemase

  • Radiculopathy

    Lesion of a spinal root that may result in pain and motor, reflex, or sensory deficits in that distribution of the root.

  • RBD

    rapid eye movement sleep behavior disorder

  • rCBF

    regional cerebral blood flow

  • RCDP

    rhizomelic chondrodysplasia punctata

  • RCVS

    reversible cerebral vasoconstriction syndrome

  • RDI

    The number of apneas (obstructive, central, or mixed) plus hypopneas per hour of total sleep time as determined by all-night polysomnography.

  • Rebound headache

    Headache syndrome resulting from overuse of abortive antimigraine drugs.

  • rebound headaches

    Headache syndrome resulting from overuse of abortive antimigraine drugs.

  • rebound hypersomnia

    Significant increase in REM sleep following discontinuation of stimulants.

  • Rebound insomnia

    A significant worsening of sleep upon discontinuation of a hypnotic, usually a benzodiazepine or similar compound.

  • Recent memory

    The memory system responsible for ongoing, high-volume learning and storage. It is tested by asking the patient to recall three items at the end of 3 to 5 minutes. Recent memories are stored in the hippocampal formation.

  • Reciprocal programs

    A test of motoric executive function that screens for perseveration or inability to inhibit a response. First the patient is asked to respond with two taps each time the examiner taps on the table once. For two taps from the examiner, he must respond with only one. The go/no-go test follows the reciprocal programs, also known as rhythmic tapping. For the go/no-go task, the patient still responds with two taps each time the examiner taps on the table once, but must inhibit any tapping when the examiner taps twice.

  • REEP1

    receptor expression-enhancing protein 1

  • Referred pain

    Pain that arises in a trigger point, but is felt at a distance, often entirely remote from its source. The pattern of referred pain is reproducibly related to its site of origin.

  • Refsum disease

    Autosomal recessive disorder characterized clinically by peripheral polyneuropathy, cerebellar ataxia, and retinitis pigmentosa; caused by impaired alpha-oxidation of the branched-chain fatty acid phytanic acid resulting in its accumulation in plasma and tissues; treated by eliminating sources of this fatty acid from the diet.

  • Reitan's Trail Making Tests A and B

    Subjects must draw a line from one stimulus to the next in a series, following numerical or alphabetical order.

  • relapsing neuropathies

    Neuropathy exhibiting a clinical course where relapses are followed by remissions, with complete or partial restoration of functional ability.

  • Relapsing neuropathy

    Neuropathy exhibiting a clinical course where relapses are followed by remissions, with complete or partial restoration of functional ability.

  • REM

    State of rapid-eye-movement sleep. The stage of sleep with highest brain activity, characterized by enhanced brain metabolism and vivid hallucinatory imagery or dreaming. There are spontaneous rapid eye movements, resting muscle activity is suppressed, and awakening threshold to nonsignificant stimuli is high. The EEG is a low-voltage, mixed-frequency, non-alpha record. REM sleep is usually 20-25% of total sleep time. It is also called "paradoxical sleep."

  • REM density

    A function that expresses the frequency of eye movements per unit time during sleep stage REM.

  • REM intensity

    A function that expresses the frequency of eye movements per unit time during sleep stage REM.

  • REM sleep episode

    The REM sleep portion of a NREM-REM sleep cycle; early in the night it may be as short as a half minute, whereas in later cycles longer than an hour. See Sleep Stage REM.

  • REM sleep episodes

    The REM sleep portion of a NREM-REM sleep cycle; early in the night it may be as short as a half minute, whereas in later cycles longer than an hour. See Sleep Stage REM.

  • REM sleep intrusion

    A brief internal of REM sleep appearing out of its usual position in the NREM-REM sleep cycle; an interposition of REM sleep in NREM sleep; sometimes appearance of a single, dissociated component of REM sleep (eg, eye movements, "drop out" of muscle tone) rather than all REM sleep parameters.

  • REM sleep latency

    The interval from sleep onset to the first appearance of stage REM sleep in the sleep episode.

  • REM sleep onset

    The designation for commencement of a REM sleep episode. Sometimes also used as a shorthand term for a sleep-onset REM sleep episode. See Sleep Onset; Sleep-Onset REM Period (SOREMP).

  • REM sleep percent

    The proportion of total sleep time constituted by the REM stage of sleep.

  • REM sleep rebound

    Lengthening and increase in frequency and density of REM sleep episodes, which result in an increase in REM sleep percent above baseline. REM sleep rebound follows REM sleep deprivation once the depriving influence is removed.

  • REM sleep recovery

    Lengthening and increase in frequency and density of REM sleep episodes, which result in an increase in REM sleep percent above baseline. REM sleep rebound follows REM sleep deprivation once the depriving influence is removed.

  • Remote memory

    The memory system responsible for retrieving information learned at some point in the distant past. Remote memory is synonymous with semantic memory.

  • Respiratory disturbance index

    The number of apneas (obstructive, central, or mixed) plus hypopneas per hour of total sleep time as determined by all-night polysomnography.

  • Respiratory disturbance index (RDI) (Apnea-hypopnea index)

    The number of apneas (obstructive, central, or mixed) plus hypopneas per hour of total sleep time as determined by all-night polysomnography.

  • Rest tremor

    A rhythmic, sinusoidal movement that resolves with movement but is often present with sustained postures.

  • restriction endonuclease

    Enzymes that digest DNA into short pieces at specific sites determined by a stretch of specific DNA sequences. DNA pieces cleaved with the same enzyme will have sticky ends that will anneal under appropriate conditions when mixed together. Treatment of these mixed pieces with the enzyme DNA ligase results in phosphodiester bond formation at the ends of DNA strands, which are already held together by complementary base-pairing, thus creating an instant piece of recombinant DNA. The recognition site is a short, symmetric sequence of bases repeated on both strands of the DNA.

  • Restriction endonucleases

    Enzymes that digest DNA into short pieces at specific sites determined by a stretch of specific DNA sequences. DNA pieces cleaved with the same enzyme will have sticky ends that will anneal under appropriate conditions when mixed together. Treatment of these mixed pieces with the enzyme DNA ligase results in phosphodiester bond formation at the ends of DNA strands, which are already held together by complementary base-pairing, thus creating an instant piece of recombinant DNA. The recognition site is a short, symmetric sequence of bases repeated on both strands of the DNA.

  • Rete mirable

    "Wonderful network": a vascular network interrupting the continuity of a vessel; generally not seen on angiography.

  • Reticuloendothelial system

    A group of cells (eg, macrophages, fibroblasts) in the liver, spleen, bone marrow, alveolar capillaries, and lymph nodes that sequester debris.

  • Retinitis pigmentosa

    A group of diseases marked by progressive loss of the retinal response, attenuation of the retinal vessels, and clumping of retinal pigment.

  • Retrograde amnesia

    Loss of access to memories for events that antedated the onset of amnesia (usually associated with head injury).

  • Reverse transcriptase

    This enzyme copies the viral RNA into DNA, up to the 5'-end of the virus, which is the same as the 3'-end. The initial transcriptor jumps to the 3'-end of the virus, base-pairing with the 3'-repeat and acts as a primer for further synthesis. After other steps, a double-stranded molecule is produced, which replicates and inserts in the host genome.

  • RFLP

    restriction fragment length polymorphism

  • rhagade

    Perioral fissures.

  • Rhagades

    Perioral fissures.

  • rhizomelia

    Either a disproportion of the length of the proximal limb (usually shortening) or deformity affects shoulder and arm or hip and thigh

  • Rhizomelic chondrodysplasia punctata

    An autosomal recessive, severe form of chondrodysplasia punctata with short limbs, growth deficiency, and shortened life span

  • RhNGF

    recombinant human nerve growth factor

  • Rho-zero cell line

    A human-derived cell line lacking mtDNA.

  • Rhombencephalic dysgenesis

    Abnormal differentiation and growth of the rhombencephalon (pons and cerebellum).

  • Ribosomal frame-shifting

    Shifting of the ribosome forwards or backwards as seen in certain viruses, bacteria, and yeast when an amino acid is limiting.

  • Rickettsia rickettsii

    Small, gram-negative pleomorphic coccobacillary microorganisms that contain both DNA and RNA and possess characteristics of both bacteria and viruses.

  • Rigidity

    Stiffness and resistance to passive movement.

  • riMLF

    rostral interstitial nucleus of the medial longitudinal fasciculus

  • Rimmed vacuole

    Nonstorage vacuoles with typical granular staining at their periphery: the staining is basophilic with hematoxylin-eosin and red with Gomori trichrome. They contain myeloid bodies and filamentous inclusions. Rimmed vacuoles are frequent in inclusion-body myositis and in various distal myopathies.

  • Rimmed vacuoles

    Nonstorage vacuoles with typical granular staining at their periphery: the staining is basophilic with hematoxylin-eosin and red with Gomori trichrome. They contain myeloid bodies and filamentous inclusions. Rimmed vacuoles are frequent in inclusion-body myositis and in various distal myopathies.

  • RLS

    restless legs syndrome

  • RNA

    ribonucleic acid

  • Rosenthal fiber

    Dense granular and osmiophilic inclusions within astrocyte processes and cell bodies, which are surrounded by glial filaments and composed of glial fibrillary acidic protein, the small heat shock proteins, alphaB-crystallin and HSP27, and ubiquitin. Their widespread distribution in Alexander disease includes prominent subpial and subependymal as well as perivascular locations. Rosenthal fibers also occur in tumors, hamartomas, and other conditions.

  • Rosenthal fibers

    Dense granular and osmiophilic inclusions within astrocyte processes and cell bodies, which are surrounded by glial filaments and composed of glial fibrillary acidic protein, the small heat shock proteins, alphaB-crystallin and HSP27, and ubiquitin. Their widespread distribution in Alexander disease includes prominent subpial and subependymal as well as perivascular locations. Rosenthal fibers also occur in tumors, hamartomas, and other conditions.

  • Rotavirus infection

    A group of RNA viruses that include gastroenteritis infections.

  • RPLS

    reversible posterior leukoencephalopathy syndrome

  • RPR

    rapid plasma reagin (test)

  • rt-PA

    recombinant tissue plasminogen activator

  • RT-PCR

    reverse transcriptase-polymerase chain reaction

  • rTMS

    repetitive transcranial magnetic stimulation

  • RTOG

    Radiation Therapy Oncology Group

  • rTPA

    recombinant tissue plasminogen activator

  • RWT

    R-wave threshold (electrocardiography)

  • RYR

    rayanodine receptor

  • RYR1

    rayanodine receptor

  • S Phase

    synthesis phase of cell growth cycle

  • S135L

    leucine substituted for serine in codon 135 of the galactose-1-phosphate uridyltransferase complementary deoxyribonucleic acid

  • Saber shin

    Thinned tibia.

  • Saccades

    A rapid conjugate eye movement either voluntarily or involuntarily produced.

  • Saccular aneurysm

    An aneurysm that has a neck through which blood enters and exits.

  • Saethre-Chotzen syndrome

    A condition in which there is coronal synostosis (unilateral or bilateral), facial asymmetry (particularly in individuals with unicoronal synostosis), ptosis, and characteristic appearance of the ear (small pinna with a prominent crus). Syndactyly of digits two and three of the hand is variably present. Also known as Saethre-Chotzen syndrome.

  • Saethre-Chotzen's syndrome

    A condition in which there is coronal synostosis (unilateral or bilateral), facial asymmetry (particularly in individuals with unicoronal synostosis), ptosis, and characteristic appearance of the ear (small pinna with a prominent crus). Syndactyly of digits two and three of the hand is variably present. Also known as Saethre-Chotzen syndrome.

  • Sagittal sinus thrombosis

    Blood clot formation in a vein draining blood within the brain.

  • Sagittal synostosis

    A condition in which there is fusion of the sagittal suture. Often the fontanel is absent or closed. A ridge can be seen, or felt, running along the top of the head between the right and left half of the skull. When viewed from above, the skull is wider near the forehead and gets narrower towards the back of the skull. When looking straight at the child's face, the forehead seems quite prominent and the sides of the skull look narrow. Also known as scaphocephaly.

  • Sanfilippo syndrome

    Autosomal recessive biochemically distinct but clinically similar diseases. These syndromes are characterized by normal facial features and stature, absence of corneal clouding, mild hepatosplenomegaly, rapidly progressive mental retardation between 2 and 10 years, hearing loss, seizures, behavioral problems, and usually death before 20 years. Types A-D have enzymatic defects of N-sulfoglucosamine sulfohydrolase (heparan-N-sulfatase), N-alpha-acetylglucosaminidase (alpha-N-acetyl-lucosaminidase), heparin acetyl-CoA:alpha-glucosaminide N-acetyltransferase (acetyl-CoA:alpha-glucosaminide acetyltransferase), and N-acetylglucosamine-6-sulfatase (N-acetylglucosamine-beta-sulfatase), respectively, each causing excretion of heparan sulfate in the urine. Also referred to as mucopolysaccharidosis III A-D.

  • Sanfilippo syndrome A-D

    Autosomal recessive biochemically distinct but clinically similar diseases. These syndromes are characterized by normal facial features and stature, absence of corneal clouding, mild hepatosplenomegaly, rapidly progressive mental retardation between 2 and 10 years, hearing loss, seizures, behavioral problems, and usually death before 20 years. Types A-D have enzymatic defects of N-sulfoglucosamine sulfohydrolase (heparan-N-sulfatase), N-alpha-acetylglucosaminidase (alpha-N-acetyl-lucosaminidase), heparin acetyl-CoA:alpha-glucosaminide N-acetyltransferase (acetyl-CoA:alpha-glucosaminide acetyltransferase), and N-acetylglucosamine-6-sulfatase (N-acetylglucosamine-beta-sulfatase), respectively, each causing excretion of heparan sulfate in the urine. Also referred to as mucopolysaccharidosis III A-D.

  • SaO2

    arterial oxygen saturation level

  • Satellite myofascial trigger point

    A trigger point that became active because the muscle was located within the zone of reference of another active trigger point.

  • satellite myofascial trigger points

    A trigger point that became active because the muscle was located within the zone of reference of another active trigger point.

  • saw-tooth wave

    A form of theta rhythm that occurs during REM sleep and is characterized by a notched appearance in the waveform. Occurs in bursts lasting up to 10 seconds.

  • Saw-tooth waves

    A form of theta rhythm that occurs during REM sleep and is characterized by a notched appearance in the waveform. Occurs in bursts lasting up to 10 seconds.

  • SBE

    subacute bacterial endocarditis

  • SBMA

    spinal and bulbar muscular atrophy

  • SBRT

    stereotactic body radiotherapy

  • SCA

    spinocerebellar ataxia

  • SCA1

    spinocerebellar ataxia type 1

  • SCA2

    spinocerebellar atrophy type 2

  • SCAD

    short-chain acyl-CoA dehydrogenase

  • SCADD

    Short-chain acyl-CoA dehydrogenase deficiency

  • Scaphocephaly

    A condition in which there is fusion of the sagittal suture. Often the fontanel is absent or closed. A ridge can be seen, or felt, running along the top of the head between the right and left half of the skull. When viewed from above, the skull is wider near the forehead and gets narrower towards the back of the skull. When looking straight at the child's face, the forehead seems quite prominent and the sides of the skull look narrow. Also known as scaphocephaly.

  • SCARMD

    severe childhood autosomal recessive muscular dystrophy

  • sCD8

    soluble CD8 protein

  • Scheie syndrome

    Relatively mild form of mucopolysaccharidosis I, with the characteristic autosomal recessive enzymatic defect of alpha-L-iduronidase. As with other mucopolysaccharidosis I syndromes dysotosis multiplex, joint abnormalities, corneal clouding, hearing loss, valvular disease, and obstructive airway disease are seen; but intelligence, stature, and life span are typically normal. Also known as mucopolysaccharidosis I-S, and previously as mucopolysaccharidosis V.

  • Schilder disease

    First described by Schilder in 1912 as large areas of demyelination involving much of the hemisphere. This term is no longer considered a distinctive entity.

  • Schizencephaly

    A structural brain abnormality characterized by congenital unilateral or bilateral clefts of the cerebral hemispheres from the pial surface to the lateral ventricles, lined by heterotopic gray matter. Affected patients are characterized by motor deficits, mental retardation, and epilepsy.

  • Schizophrenia

    Any of a group of severe emotional disorders, usually of psychotic proportions, characterized by withdrawal from reality, delusions, hallucinations, ambivalence, inappropriate affect, and withdrawn, bizarre, or regressive behavior.

  • Schwartz-Jampel

    Autosomal recessive disorder manifested by a combination of blepharospasm, blepharophimosis, dwarfism, muscular hypertrophy, generalized muscular stiffness, and myotonia.

  • Schwartz-Jampel syndrome

    Autosomal recessive disorder manifested by a combination of blepharospasm, blepharophimosis, dwarfism, muscular hypertrophy, generalized muscular stiffness, and myotonia.

  • Sciatic neuropathies

    A disorder characterized by selective dysfunction of the sciatic nerve(s) due to axonal loss or segmental demyelination or both.

  • Sciatic neuropathy

    A disorder characterized by selective dysfunction of the sciatic nerve(s) due to axonal loss or segmental demyelination or both.

  • Sciatica

    Back pain with radiation to the leg, suggesting nerve root compromise.

  • SCIP

    5-bromo-chloro-3-indolyl phosphate

  • SCM

    split cord malformation (or sodium channel myotonia)

  • SCP2

    sterol carrier protein X

  • SCPXT

    sterol carrier protein X thiolase

  • SDMT

    Symbol Digit Modalities Test

  • SEADL

    Schwab and England Activities of Daily Living

  • Secondary dystonia

    Dystonia that occurs as the result of a cerebral insult.

  • Secondary myoclonic status epilepticus

    Myoclonic status epilepticus that occurs in patients with symptomatic generalized epilepsies.

  • Secondary myofascial trigger point

    A trigger point that became active because its muscle was overloaded as a synergist substituting for, or as an antagonist countering the forces of, the muscle that contained the primary trigger point.

  • Secondary myofascial trigger points

    A trigger point that became active because its muscle was overloaded as a synergist substituting for, or as an antagonist countering the forces of, the muscle that contained the primary trigger point.

  • SEEG

    stereoelectroencephalography

  • SEER

    surveillance, epidemiology, and end results

  • Segmental demyelination

    A patchy loss of myelin.

  • SEM

    standard error of the mean

  • Semantic alexia

    Inability to understand written language despite intact phonological and orthographic processing. Semantic alexia is frequently found in dementia.

  • Semantic aphasia

    Language understanding defect characterized by difficulties in comprehending the relationship among the words in a sentence, particularly when spatial and temporal relationships are included.

  • Semantic memory

    The store of knowledge of prior events, facts, and knowledge of the lexicon.

  • Semantic paralexia

    Reading error consisting of semantically-related word substitution.

  • Semantic paraphasic error

    Verbal error based on substituting one word for another (eg, "spoon" for "fork"), as opposed to phonemic paraphasic error.

  • semantic paraphasic errors

    Verbal error based on substituting one word for another (eg, "spoon" for "fork"), as opposed to phonemic paraphasic error.

  • sensitization

    Increased responsiveness of nociceptive neurons to their normal input, and/or recruitment of a response to normally subthreshold inputs.

  • Sensory ganglionitis

    An acquired disorder affecting predominantly large-fiber sensory peripheral axons. This neuropathy typically affects patients in middle age, and, while it may present acutely or subacutely, it is likely to remain for many years and not respond well to therapy. Neurophysiologic and pathological studies reveal axonal degeneration of large-diameter sensory axons. Upon biopsy, inflammatory foci are often found in dorsal root ganglia. Idiopathic sensory ganglionitis can only be distinguished from that associated with Sjogren syndrome or small cell carcinoma of the lung by excluding these two disorders.

  • Sensory modality

    A basic sensation such as sensation to temperature, joint movement, vibration, or pain that requires its own receptor type for transmission to the central nervous system. Complex sensations utilizing several of the basic modalities, such as graphesthesia (discerning a letter traced on the skin) are not sensory modalities.

  • Sensory neuropathies associated with anti-GD1b ganglioside antibodies

    A peripheral nerve disorder predominantly affecting sensory fibres and occurring in association with circulating serum antibodies to the ganglioside GD1b.

  • Sepiapterin reductase deficiency

    An autosomal recessive disorder of tetrahydrobiopterin metabolism resulting in reduced synthesis of biogenic amine neurotransmitters. Sepiapterin reductase is the last enzyme required in the biosynthetic pathway for tetrahydrobiopterin synthesis. The disorder does not result in hyperphenylalaninemia. Clinical phenotype has included a mixed movement disorder that includes dystonia, myoclonus, spasticity, and choreoathetotic movements. Other symptoms include oculomotor apraxia, cognitive dysfunction, diurnal variation of symptoms, and excessive daytime sleepiness.

  • SEPN1

    selenoprotein N

  • Sepsis

    Generalized system infection.

  • ser

    serine

  • Serologic

    Relating to immunologic proteins in the serum.

  • Severe brain injury

    Brain injury caused by external forces resulting in a Glasgow Coma Scale score of between 3 and 8.

  • Severe head injury

    Brain injury caused by external forces resulting in a Glasgow Coma Scale score of between 3 and 8.

  • Severe hyperhomocysteinemia

    Fasting plasma total homocysteine concentration greater than 100 micromolars.

  • Severe myoclonic epilepsy in infancy

    Epileptic syndrome of genetic origin characterized by infantile onset, multiple seizure types, and progressive cognitive decline.

  • Severity criteria

    Criteria for establishing the severity of a particular sleep disorder according to categories: mild, moderate, or severe.

  • SF-36

    Short Form-36

  • SFEMG

    single-fiber EMG

  • SGLPG

    sulfated glucuronic acid lactosaminylparagloboside

  • SGOT

    serum glutamic-oxaloacetic transaminase

  • SGPG

    sulfogluceronyl paragloboside

  • SGPT

    serum glutamic-pyruvic transaminase

  • SGS

    secondarily generalized seizures

  • SGT

    serine glutamyltransferase

  • SHEP

    Systolic Hypertension in the Elderly Program

  • SHH

    Sonic hedgehog gene

  • Short sleeper

    An individual who habitually sleeps sustantially less during a 24-hour period than is expected for a person of his or her age.

  • Short-term memory

    The memory system that involves newly learned material. Short-term memory is sometimes used to encompass immediate and recent memory.

  • SIADH

    Syndrome of inappropriate secretion of antidiuretic hormone

  • Sialidosis

    Cherry-red spot myoclonus syndrome due to a primary neuraminidase defect. Type I is normosomatic; type II is dysmorphic. Also known as mucolipidosis I.

  • Sickle cell disease

    Hereditary disorder of hemoglobin causing abnormal erythrocyte shape resulting in a multisystem ischemic and occasionally hemorrhagic state.

  • sIL-2R

    soluble interleukin-2 receptor

  • Simpson grade

    Grading scale for the removal of meningiomas: (I) macroscopic complete removal with excision of dural attachment, (II) macroscopically complete with coagulation of dura, (III) macroscopically complete without removing or coagulating dura, (IV) partial removal, and (V) decompression only.

  • Sinus thrombosis

    Blood clot formation in a vein draining blood within the brain.

  • SIRS

    systemic inflammatory response syndrome

  • SLC39A8

    Solute carrier family 39, member A8 (manganese transporter)

  • SLE

    systemic lupus erythematosus

  • Sleep apnea syndrome

    Repetitive episodes of respiratory alteration that occur during sleep, usually associated with a reduction in oxygen saturation.

  • Sleep architecture

    The NREM-REM sleep stage and cycle infrastructure of sleep understood from the vantage point of the quantitative relationship of these components to each other. Often plotted in the form of a histogram.

  • Sleep diary

    A daily, written record of a person's sleep-wake pattern containing such information as time of retiring and arising, time in bed, estimated total sleep time, number and duration of sleep interruptions, quality of sleep, daytime naps, use of medications or caffeine beverages, nature of waking activities.

  • Sleep efficiency

    The proportion of sleep in the episode potentially filled by sleep, ie, the ratio of total sleep time to time in bed.

  • Sleep efficiency (or sleep efficiency index)

    The proportion of sleep in the episode potentially filled by sleep, ie, the ratio of total sleep time to time in bed.

  • Sleep efficiency index

    The proportion of sleep in the episode potentially filled by sleep, ie, the ratio of total sleep time to time in bed.

  • Sleep episode

    An interval of sleep that may be voluntary or involuntary. In the sleep laboratory, the sleep episode occurs from the time of "lights out" to the time of "lights on." The major sleep episode is usually the longest daily sleep episode.

  • sleep episodes

    An interval of sleep that may be voluntary or involuntary. In the sleep laboratory, the sleep episode occurs from the time of "lights out" to the time of "lights on." The major sleep episode is usually the longest daily sleep episode.

  • Sleep homeostasis

    The basic principle of sleep regulation. EEG slow waves (0.5 to 4 Hz), a correlate of sleep intensity, serve as an indicator of sleep homeostasis in NREM sleep.

  • Sleep hygiene

    The conditions and practices that promote continuous and effective sleep. These include regularity of bedtime and arise time; conformity of time spent in bed to the time necessary for sustained and individually adequate sleep (ie, the total sleep time sufficient to avoid sleepiness when awake); restriction of alcohol and caffeine beverages prior to bedtime; and employment of exercise, nutrition, and environmental factors so that they enhance, not disturb, restful sleep.

  • Sleep interruption

    Breaks in sleep resulting in arousal and wakefulness; fragmentation; restlessness.

  • Sleep latency

    The duration of time from "lights out," or bedtime, to the onset of sleep.

  • Sleep log

    A daily, written record of a person's sleep-wake pattern containing such information as time of retiring and arising, time in bed, estimated total sleep time, number and duration of sleep interruptions, quality of sleep, daytime naps, use of medications or caffeine beverages, nature of waking activities.

  • Sleep mentation

    The imagery and thinking experienced during sleep. Sleep mentation usually consists of combinations of images and thoughts during REM sleep. Imagery is vividly expressed in dreams involving all the senses in approximate proportion to their waking representations. Mentation is experienced generally less distinctly in NREM sleep, but it may be quite vivid in stage 2 sleep, especially toward the end of the sleep episode. Mentation at sleep onset (hypnagogic reverie) can be as vivid as in REM sleep.

  • Sleep onset

    The transition from awake to sleep, normally to NREM stage 1 sleep, but in certain conditions, such as infancy and narcolepsy, into stage REM sleep. Most polysomnographers accept EEG slowing, reduction, and eventual disappearance of alpha activity, presence of EEG vertex sharp transients, and slow rolling eye movements (the components of NREM stage 1) as sufficient for sleep onset; others require appearance of stage 2 patterns. See Latency; Sleep stages.

  • Sleep paralysis

    Immobility of the body that occurs in the transition from sleep to wakefulness that is a partial manifestation of REM sleep.

  • Sleep pattern

    A person's clock hour schedule of bedtime and arise time as well as nap behavior; may also include time and duration of sleep interruptions. See Sleep-Wake Cycle; Circadian Rhythm; Sleep Log.

  • Sleep pattern (24-Hour Sleep-Wake Pattern)

    A person's clock hour schedule of bedtime and arise time as well as nap behavior; may also include time and duration of sleep interruptions. See Sleep-Wake Cycle; Circadian Rhythm; Sleep Log.

  • Sleep spindle

    Spindle-shaped bursts of 11.5-15-Hz waves lasting 0.5-1.5 seconds. Generally diffuse, but of highest voltage over the central regions of the head. The amplitude is generally less than 50 'V in the adult. One of the identifying EEG features of NREM stage 2 sleep; may persist into NREM stages 3 and 4; generally not seen in REM sleep.

  • sleep stage

    Distinctive stages of sleep, best demonstrated by polysomnographic recordings of the EEG, EOG, and EMG.

  • Sleep stage 1

    A stage of NREM sleep that occurs at sleep onset or that follows arousal from sleep stages 2, 3, 4, or REM. It consists of a relatively low-voltage EEG with mixed frequency, mainly theta activity and alpha activity of less than 50% of the scoring epoch. It contains EEG vertex waves and slow rolling eye movements; no sleep spindles, K complexes, or REMs. Stage 1 normally represents 4-5% of the major sleep episode.

  • Sleep stage 1 (NREM stage 1)

    A stage of NREM sleep that occurs at sleep onset or that follows arousal from sleep stages 2, 3, 4, or REM. It consists of a relatively low-voltage EEG with mixed frequency, mainly theta activity and alpha activity of less than 50% of the scoring epoch. It contains EEG vertex waves and slow rolling eye movements; no sleep spindles, K complexes, or REMs. Stage 1 normally represents 4-5% of the major sleep episode.

  • Sleep stage 2

    A stage of NREM sleep characterized by the presence of sleep spindles and K complexes present in a relatively low-voltage, mixed-frequency EEG background; high-voltage delta waves may comprise up to 20% of stage 2 epochs; usually accounts for 45-55% of the major sleep episode.

  • Sleep stage 2 (NREM Stage 2)

    A stage of NREM sleep characterized by the presence of sleep spindles and K complexes present in a relatively low-voltage, mixed-frequency EEG background; high-voltage delta waves may comprise up to 20% of stage 2 epochs; usually accounts for 45-55% of the major sleep episode.

  • Sleep stage 3

    A stage of NREM sleep defined by at least 20% and not more than 50% of the episode consisting of EEG waves less than 2 Hz and more than 75 'V (high-amplitude delta waves); a "delta" sleep stage; with stage 4, it constitutes "deep" NREM sleep, so-called slow wave sleep (SWS); often combined with stage 4 into NREM sleep stage 3/4 because of the lack of documented physiological differences between the two; appears usually only in the first third of the sleep episode; usually comprises 4-6% of total sleep time.

  • Sleep stage 3 (NREM stage 3)

    A stage of NREM sleep defined by at least 20% and not more than 50% of the episode consisting of EEG waves less than 2 Hz and more than 75 'V (high-amplitude delta waves); a "delta" sleep stage; with stage 4, it constitutes "deep" NREM sleep, so-called slow wave sleep (SWS); often combined with stage 4 into NREM sleep stage 3/4 because of the lack of documented physiological differences between the two; appears usually only in the first third of the sleep episode; usually comprises 4-6% of total sleep time.

  • Sleep stage 4

    All statements concerning NREM sleep stage 3 apply to stage 4 except that high-voltage, EEG slow waves persist 50% or more of the epoch; NREM sleep stage 4 usually represents 12-15% of total sleep time. Sleepwalking, sleep terrors, and confusional arousal episodes generally start in stage 4 or during arousals from this stage. See Sleep Stage 3.

  • Sleep stage 4 (NREM stage 4)

    All statements concerning NREM sleep stage 3 apply to stage 4 except that high-voltage, EEG slow waves persist 50% or more of the epoch; NREM sleep stage 4 usually represents 12-15% of total sleep time. Sleepwalking, sleep terrors, and confusional arousal episodes generally start in stage 4 or during arousals from this stage. See Sleep Stage 3.

  • Sleep stage demarcation

    The significant polysomnographic characteristics that distinguish the boundaries of the sleep stages. In certain conditions and with drugs, sleep stage demarcations may be blurred or lost, making it difficult to identify certain stages with certainty or to distinguish the temporal limits of sleep stage lengths.

  • Sleep stage episode

    A sleep stage interval that represents the stage in a NREM-REM sleep cycle; easiest to comprehend in relation to REM sleep, which is a homogeneous stage, ie, the fourth REM sleep episode is in the fourth sleep cycle (unless a prior REM episode was skipped). If one interval of REM sleep is separated from another by more than 20 minutes, they constitute separate REM sleep episodes (and are in separate sleep cycles); a sleep stage episode may be of any duration.

  • Sleep stages

    Distinctive stages of sleep, best demonstrated by polysomnographic recordings of the EEG, EOG, and EMG.

  • Sleep structure

    Similar to sleep architecture. However, in addition to encompassing sleep stages and sleep cycle relationships, sleep structure assesses the within-stage qualities of the EEG and other physiological attributes.

  • Sleep terrors

    Fearful confusional arousals from first hour of sleep from stage 3 or 4 without dream content or recall but with high autonomic outflow.

  • Sleep-maintenance DIMS

    A disturbance in maintaining sleep, once achieved; persistently interrupted sleep without difficulty falling asleep. Synonymous with sleep continuity disturbance.

  • Sleep-maintenance DIMS (Insomnia)

    A disturbance in maintaining sleep, once achieved; persistently interrupted sleep without difficulty falling asleep. Synonymous with sleep continuity disturbance.

  • Sleep-maintenance disturbance in Maintaining Sleep

    A disturbance in maintaining sleep, once achieved; persistently interrupted sleep without difficulty falling asleep. Synonymous with sleep continuity disturbance.

  • Sleep-maintenance insomnia

    A disturbance in maintaining sleep, once achieved; persistently interrupted sleep without difficulty falling asleep. Synonymous with sleep continuity disturbance.

  • Sleep-onset REM period

    The beginning of sleep by entrance directly into stage REM sleep. The onset of REM sleep occurs within 10 minutes of sleep onset.

  • Sleep-onset REM period (SOREMP)

    The beginning of sleep by entrance directly into stage REM sleep. The onset of REM sleep occurs within 10 minutes of sleep onset.

  • Sleep-related erection

    The natural periodic cycle of penile erections that occur during sleep, typically associated with REM sleep. Sleep-related erectile activity can be characterized by four phases: T-up (ascending tumescence), T-max (plateau maximal tumescence), T-down (detumescence), and T-zero (no tumescence). Polysomnographic assessment of sleep-related erections is useful for differentiating organic from nonorganic erectile dysfunction.

  • Sleep-related erections

    The natural periodic cycle of penile erections that occur during sleep, typically associated with REM sleep. Sleep-related erectile activity can be characterized by four phases: T-up (ascending tumescence), T-max (plateau maximal tumescence), T-down (detumescence), and T-zero (no tumescence). Polysomnographic assessment of sleep-related erections is useful for differentiating organic from nonorganic erectile dysfunction.

  • Sleep-wake change

    When sleep as a whole or in part is moved to a time of customary waking activity, and the latter is moved to the time of the major sleep episode; common in jet lag and shift work.

  • Sleep-wake cycle

    Basically, the clock hour relationships of the major sleep and wake episodes in the 24-hour cycle. See Phase Transition; Circadian Rhythm.

  • Sleep-wake reversal

    When sleep as a whole or in part is moved to a time of customary waking activity, and the latter is moved to the time of the major sleep episode; common in jet lag and shift work.

  • Sleep-wake shift

    When sleep as a whole or in part is moved to a time of customary waking activity, and the latter is moved to the time of the major sleep episode; common in jet lag and shift work.

  • Sleep-wake transition disorder

    A disorder that occurs during the transition from wakefulness to sleep or from one sleep stage to another. A form of the parasomnias; not a dyssomnia.

  • Slow wave sleep

    Sleep characterized by EEG waves of duration slower than 4 Hz. Synonymous with sleep stages 3 plus 4 combined. See Delta Sleep Stage.

  • Slow wave sleep (SWS)

    Sleep characterized by EEG waves of duration slower than 4 Hz. Synonymous with sleep stages 3 plus 4 combined. See Delta Sleep Stage.

  • Sly syndrome

    Autosomal recessive mucopolysaccharidosis caused by a deficiency in beta-glucuronidase with heparan sulfate and chondroitin sulfate excreted in the urine. Hurler-like features are seen including dysotosis multiplex, hepatosplenomegaly, and short stature.Intelligence ranges from severely impaired to normal. Also known as mucopolysaccharidosis VII.

  • SMA

    spinal muscular atrophy

  • SMEI

    Epileptic syndrome of genetic origin characterized by infantile onset, multiple seizure types, and progressive cognitive decline.

  • SMN

    survival motor neuron

  • SMN1

    telomeric survival motor neuron

  • SMN2

    centromeric survival motor neuron

  • SMNc

    centromeric survival motor neuron

  • SMNt

    telomeric survival motor neuron

  • SMPA

    Scapuloperoneal muscular atrophy

  • SNc

    substantia nigra pars compacta

  • SNP

    single nucleotide polymorphism

  • SNpc

    substantia nigra pars compacta

  • SNpr

    substantia nigra pars reticulata

  • SNPs

    single nucleotide polymorphism

    Small stretches of DNA that differ in only one base are called single nucleotide polymorphisms and serve to distinguish one individual's genetic material from that of another. Single nucleotide polymorphisms occur once in every 300 nucleotides on average, which means there are approximately 10 million single nucleotide polymorphisms in the human genome. Identification of single nucleotide polymorphisms is important as it helps in understanding the genetic basis of common human diseases.

  • SNr

    substantia nigra pars reticulata

  • SNRPN

    small nuclear ribonucleoprotein N

  • Snuffles

    Purulent or bloody rhinitis.

  • SNURF

    small ribinucleoprotein N upstream reading frame

  • SOD

    superoxide dismutase

  • Somatoparaphrenia

    Delusional disorder of abnormal bodily interpretation, especially of one's own body or body part. Denial of limb ownership, and the belief that one has an extra limb (supernumerary limb or phantom limb), such as a third arm, is included with this definitition.

  • Somatosensory evoked potential

    Recorded responses from various central nervous system locations obtained after the stimulation of peripheral nerves, most commonly the median or tibial nerves.

  • Somatosensory evoked potentials

    Recorded responses from various central nervous system locations obtained after the stimulation of peripheral nerves, most commonly the median or tibial nerves.

  • SOREMP

    The beginning of sleep by entrance directly into stage REM sleep. The onset of REM sleep occurs within 10 minutes of sleep onset.

  • Southern blot

    A standard method of analyzing the structure of DNA cleaved by restriction endonucleases. The fragments of DNA are subsequently separated by size by gel electrophoresis. The DNA fragments are then denatured to separate the two strands of DNA. The single-strand DNA molecules are then blot transferred from the gel on to the surface of a solid-phase filter which is an opposed nitrocellulose or nylon membrane. The membrane serves as a lattice to capture and bind the single strands of DNA. After the DNA is heat-fixed to the membrane, the specific DNA sequence can be identified by incubating the filter with a single strand of radioactive DNA (called the probe) complementary to the recombinant DNA sequence of interest. The resulting hybridized labeled DNA:DNA complex, which is bonded to the nitrocellulose/nylon framework, is developed on an X-ray film to identify the original DNA fragments.

  • southern blot test

    A standard method of analyzing the structure of DNA cleaved by restriction endonucleases. The fragments of DNA are subsequently separated by size by gel electrophoresis. The DNA fragments are then denatured to separate the two strands of DNA. The single-strand DNA molecules are then blot transferred from the gel on to the surface of a solid-phase filter which is an opposed nitrocellulose or nylon membrane. The membrane serves as a lattice to capture and bind the single strands of DNA. After the DNA is heat-fixed to the membrane, the specific DNA sequence can be identified by incubating the filter with a single strand of radioactive DNA (called the probe) complementary to the recombinant DNA sequence of interest. The resulting hybridized labeled DNA:DNA complex, which is bonded to the nitrocellulose/nylon framework, is developed on an X-ray film to identify the original DNA fragments.

  • Span length

    The amount of material, usually digits or words, that a person can recall immediately after presentation under circumstances of no distraction.

  • SPARC

    Secreted protein acidic and rich in cysteine

  • Spasmodic dysphonia

    Can be divided into (1) adductor spasmodic dysphonia, which is the result of the vocal cords' hyperadducting, creating a strained, choked voice, and (2) abductor spasmodic dysphonia, resulting from the vocal cords' being pulled apart, creating a weak, breathy voice.

  • Spasmodic dysphonia (laryngeal dystonia)

    Can be divided into (1) adductor spasmodic dysphonia, which is the result of the vocal cords' hyperadducting, creating a strained, choked voice, and (2) abductor spasmodic dysphonia, resulting from the vocal cords' being pulled apart, creating a weak, breathy voice.

  • Spasmus nutans

    A benign transitory asymmetric nystagmus, often with head bobbing and head tilt.

  • Spatial acalculia

    Disturbance in calculation abilities resulting from spatial ability defects.

  • SPECT

    Single photon emission computed tomography

  • Speech reception threshold

    The intensity at which a patient can correctly repeat half of a sequence of common 2-syllable words delivered with equal emphasis on both syllables. It is a measure of the ability to hear and understand speech. It also serves as a check of the validity of tone results.

  • SPEP

    serum protein electrophoresis

  • SPG

    spastic paraplegia

  • SPG1

    spastic paraplegia, X-linked, complicated, with mutation in the L1CAM gene

  • SPG2

    spastic paraplegia, X-linked, uncomplicated (or pure), with mutation in the proteolipid protein gene; also, spastic paraplegia, X-linked, complicated, with mutation in the proteolipid protein gene.

  • sphingolipid

    A ceramide with a C-1 esterification group of phosphorylcholine forms a sphingomyelin, with monosaccharide or oligosaccharide forms glycosphingolipid, and with an oligosaccharide plus 1 to 4 molecules of sialic acid forms a ganglioside.

  • Sphingolipids

    A ceramide with a C-1 esterification group of phosphorylcholine forms a sphingomyelin, with monosaccharide or oligosaccharide forms glycosphingolipid, and with an oligosaccharide plus 1 to 4 molecules of sialic acid forms a ganglioside.

  • Spillover pain zone

    The region beyond the essential pain zone where some, but not all, patients experience referred pain from an active trigger point.

  • Spinal cord hemorrhage

    Acute myelopathy secondary to the mass effect produced by a hematoma within the spinal cord.

  • spinal cord hemorrhages

    Acute myelopathy secondary to the mass effect produced by a hematoma within the spinal cord.

  • Spinal cord infarction

    Acute myelopathy secondary to inadequate blood supply to certain areas of the spinal cord.

  • spinal cord infarctions

    Acute myelopathy secondary to inadequate blood supply to certain areas of the spinal cord.

  • spinal cord vascular malformation

    Abnormal vascular structures inside the spinal cord, or in the adjacent meninges, that may affect spinal cord function due to mass effect, acute hemorrhage, venous congestion, or transient ischemia due to steal flow phenomena.

  • Spinal cord vascular malformations

    Abnormal vascular structures inside the spinal cord, or in the adjacent meninges, that may affect spinal cord function due to mass effect, acute hemorrhage, venous congestion, or transient ischemia due to steal flow phenomena.

  • Spindle REM sleep

    A condition in which sleep spindles persist atypically in REM sleep; seen in chronic insomnia conditions and occasionally in the first REM period.

  • Split-brain

    The brain following surgical division of the corpus callosum.

  • SPMD

    scapuloperoneal muscular dystrophy (or disease)

  • SPMS

    secondary progressive multiple sclerosis

  • SpO2

    arterial oxygen saturation level measured by pulse oximetry

  • SPSE

    simple partial status epilepticus

  • SR

    sarcoplasmic reticulum

  • SS-A

    Sjogren syndrome-A, anti-Ro

  • SS-B

    Sjogren syndrome-B, anti-La

  • SSADH

    succinic semialdehyde dehydrogenase

  • SSCP

    single-strand conformation polymorphism

  • SSD

    sickle cell disease

  • ssDNA

    single-stranded deoxyribonucleic acid

  • SSE

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • SSEP

    somatosensory evoked potential

  • SSPE

    subacute sclerosing panencephalitis

  • SSRI

    selective serotonin reuptake inhibitor

  • SSS

    superior sagittal sinus

  • STAI

    State Trait Anxiety Inventory

  • Standard deviation

    A method of determining, on the average, how much the individual values differ from the mean. Standard deviation is equal to the average of the squared deviations from the mean. The smaller the standard deviation is, the less each score varies from the mean.

  • Standard error

    A standard deviation of sample means is called standard error of means. Standard error can be used to construct a confidence interval. Standard error is equal to the standard deviation divided by the square root of the sample size.

  • Stapedius muscle

    A muscle that has its origin at the interior of the pyramidal eminence of the tympanic cavity and its insertion at the neck of the stapes; innervated by the facial nerve; serves to dampen movement of the stapes.

  • Startle epilepsy

    An epilepsy syndrome characterized by tonic and generalized tonic-clonic seizures that occur in response to a sudden stimuli, typically associated with underlying neurologic impairment.

  • Startle syndrome

    An exaggerated startle response to a surprise stimulus.

  • Startle syndromes

    An exaggerated startle response to a surprise stimulus.

  • Status migrainosus

    Acute migraine that is not relieved after several attempts at treatment.

  • Steal phenomenon

    Shunting of blood away from a nervous system location causing transient or persistent ischemia or infarction. Shunting could result from hemodynamic factors causing low or reversal of arterial flow due to arterial occlusion, stenosis, hypoplasia, kinking, or compression of high-flow that leads to by-passing of local microcirculation or reduced head of pressure in other arterial branches due to arteriovenous malformations and fistulas. Hemodynamic effects are subject to modulation by posture, exercise, hemoglobin, oxygen saturation, blood pressure, and similar factors.

  • Steatosis

    Fatty degeneration.

  • Stevens-Johnson syndrome

    Severe idiosyncratic reaction characterized by skin eruption and mucosal and endothelial damage.

  • stimulant-dependent sleep disorder

    Reduction of sleepiness or suppression of sleep by central stimulants, and resultant alterations in wakefulness following drug abstinence.

  • STN

    subthalamic nucleus

  • STORCH

    syphilis, toxoplasmosis, rubella, cytomegalovirus, and herpesvirus

  • Striatum

    A subcortical mass of gray and white substance in front of and lateral to the thalamus in each cerebral hemisphere.

  • Striatum (Corpus striatum)

    A subcortical mass of gray and white substance in front of and lateral to the thalamus in each cerebral hemisphere.

  • Stroke volume

    The average of the volume of CSF moving caudally during cardiac systole and rostrally during cardiac diastole as measured in the cerebral aqueduct on phase-contrast CSF velocity MRI.

  • Stroop color test

    Subjects are given a card with words printed in different colors. Each word represents a color but is printed in the wrong color of ink; for example, the word "red" is written in blue ink. Subjects are instructed to ignore the words and just report the co

  • Stroop interference test

    Subjects are given a card with words printed in different colors. Each word represents a color but is printed in the wrong color of ink; for example, the word "red" is written in blue ink. Subjects are instructed to ignore the words and just report the color of ink they see. Subjects with frontal dysexecutive syndrome will be tempted to say "red" when the word "red" is written in blue.

  • Stupor

    A state of deep sleep, from which the patient can be aroused only with repeated and vigorous stimulation.

  • SUAS

    selective upper airway stimulation

  • subacute necrotizing encephalomyelopathies

    A neurodegenerative disorder that involves the basal ganglia and brainstem, usually presenting in infancy, with pathological findings of necrosis and microvascular proliferation.

  • Subacute necrotizing encephalomyelopathy

    A neurodegenerative disorder that involves the basal ganglia and brainstem, usually presenting in infancy, with pathological findings of necrosis and microvascular proliferation.

  • subacute spongiform encephalopathies

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • Subacute spongiform encephalopathies (Prion diseases)

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • subacute spongiform encephalopathy

    Progressive fatal processes that have variable clinical manifestations with a similar noninflammatory pathology and pathogenesis. These diseases are associated and probably caused by the accumulation of an abnormal form of the prion protein. They include kuru (a cerebellar degeneration among the Fore tribesmen of New Guinea), fatal familial insomnia (a rare autosomal dominantly inherited disease characterized by insomnia and dysautonomia), sporadic fatal insomnia (a non-inherited disease similar to fatal familial insomnia), and thalamic dementia (probably a form of fatal familial insomnia).

  • Subcortical band heterotopia

    A developmental brain abnormality associated with seizures and mental retardation. Patients are typically female and present during childhood with mental retardation/developmental delays and epilepsy that is often difficult to control with medication. It is an inherited disorder of epilepsy and mental retardation on the X-chromosome, and is due to a defect in migration of neurons to the cortex during gestation. There is currently no specific treatment, but genetic testing is available.

  • Subcortical dementia

    Pattern of cognitive deficits associated with illnesses, such as Huntington disease, Parkinson disease, and progressive supranuclear palsy, that involve predominantly subcortical structures. Characteristic features include forgetfulness, slowness of thought processes, impaired ability to manipulate acquired knowledge, and sometimes accompanying apathy and depression. There is a lack of frank amnesia, agnosia, and aphasia, as are seen in cortical dementias such as Alzheimer disease.

  • subcortical laminar heterotopia

    A developmental brain abnormality associated with seizures and mental retardation. Patients are typically female and present during childhood with mental retardation/developmental delays and epilepsy that is often difficult to control with medication. It is an inherited disorder of epilepsy and mental retardation on the X-chromosome, and is due to a defect in migration of neurons to the cortex during gestation. There is currently no specific treatment, but genetic testing is available.

  • Subdural empyema

    Bacterial (or possibly other) infection occurring between the outermost layer of the cranial or spinal meninges, the dura, and the middle layer of the meninges, the arachnoid.

  • subdural empyemas

    Bacterial (or possibly other) infection occurring between the outermost layer of the cranial or spinal meninges, the dura, and the middle layer of the meninges, the arachnoid.

  • Subluxation

    Partial dislocation of a joint.

  • Substantia innominata

    The area under the anterior commissure; the subcommissural region has a number of groups of cells that are in contact with various fiber bundles traversing the region. In the subcommissural region the most obvious cells are the nucleus basalis. The term "substantia innominata" has at times been used to denote the nucleus basalis.

  • Substantia nigra

    The layer of gray substance separating the tegmentum of the midbrain from the crus cerebri.

  • Subthalamic nuclei

    A nucleus on the medial side of the junction of the internal capsule and crus cerebri.

  • Sulfatide activator deficiency

    A disorder clinically indistinguishable from metachromatic leukodystrophy, and caused by a deficiency of sulfatide activator protein (saposin 1 or saposin b) rather than arylsulfatase A.

  • SUNCT

    short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing

  • Sundowning

    Agitation and other behavioral disturbances in a demented patient that typically start in the early evening and may extend into the night.

  • Supplementary motor area

    A region of the medial frontal cortex, immediately anterior to the primary motor cortex, that is thought to be principally active during movement preparation.

  • Supratentorial hemispheric low-grade glioma

    A group of brain tumors that are varied histologically but appear to be less malignant than faster-growing tumors.

  • Supratentorial hemispheric low-grade gliomas

    A group of brain tumors that are varied histologically but appear to be less malignant than faster-growing tumors.

  • SVRI

    systemic vascular resistance index

  • SWS

    Sleep characterized by EEG waves of duration slower than 4 Hz. Synonymous with sleep stages 3 plus 4 combined. See Delta Sleep Stage.

  • Sydenham chorea

    A major manifestation of rheumatic fever, resulting from antibodies raised against beta-hemolytic group A streptococcus that cross-react with basal ganglia epitopes. It is clinically characterized by chorea associated with decreased muscle tone, motor impersistence, decreased verbal fluency, obsessive-compulsive behavior and other behavioral abnormalities.

  • Symbol digit modalities test

    Subjects are shown a key in which each box in the upper row has a symbol in it and each box below it has a number. They are then instructed to look at rows of boxes that have symbols on top but empty boxes below and fill each empty box with the appropriate number based on the key.

  • sympathomimetic drug

    Drugs whose mechanism of action includes stimulation of adrenergic receptors directly or indirectly.

  • Sympathomimetic drugs

    Drugs whose mechanism of action includes stimulation of adrenergic receptors directly or indirectly.

  • Sympathomimetics

    Drugs whose mechanism of action includes stimulation of adrenergic receptors directly or indirectly.

  • Symptomatic myoclonic status epilepticus

    Myoclonic status epilepticus that occurs in the setting of anoxic brain injury or neurodegenerative, infectious, inflammatory, or toxic-metabolic disease.

  • Synaptophysin

    A glycoprotein, usually detected by immunohistochemistry, associated with presence of synapses found on the surface of many, but not all, neurones. It is often absent on immature neurones.

  • Synechiae

    Adhesion of adjacent tissues.

  • Synophrys

    Joining of the eyebrows in the midline with medial hypertrichosis.

  • Synophthalmia

    Variable fusion of eyes.

  • T-cell

    thymus derived cell

  • t-PA

    tissue plasminogen activator

  • T1-weighted

    spin-lattice of longitudinal relaxation time (MRI scan)

  • T1/2

    half-life

  • T2-weighted

    spin-spin or transverse relaxation time (MRI scan)

  • T3

    triodothyronine

  • T4

    thyroxine

  • Tactile anomia

    Inability to name an object solely through touch.

  • TAO

    thyroid-associated orbitopathy

  • Tapir mouth

    Indicates facial weakness and is associated with the inability to purse lips or to whistle. Also known as pout, pouting mouth, or bouche de tapir.

  • Taut band

    The group of taut muscle fibers that is associated with a myofascial trigger point and is identifiable by tactile examination of the muscle.

  • TCD

    transcranial doppler

  • TCMA

    transcortical motor aphasia

  • TCSA

    transcortical sensory aphasia

  • TDP-43

    TAR DNA binding protein-43

  • Teichopsia

    Shimmering colored lights accompanied by blank spots in the visual field, usually associated with migraine.

  • teichopsias

    Shimmering colored lights accompanied by blank spots in the visual field, usually associated with migraine.

  • Tela

    Web-like structure; any thin membrane

  • Teratogenic effect

    Effect of fetal tissue malformation caused by extrinsic/environmental factors.

  • tetrahydrobiopterin metabolism disorder

    Disorders in the cofactor formed from GTP, required in association with phenylalanine hydroxylase to convert phenylalanine to tyrosine. It is also involved in tyrosine hydroxylase (catecholamine synthesis) and tryptophan hydroxylase (serotonin synthesis) reactions. First described as phenylketonuria unresponsive to diet. Neonatal symptoms often include poor suck, hypotonia, microcephaly, and low birth weight, with later onset of increased salivation, pin-point pupils, sweating, oculogyric crises, seizures, myoclonus, dysphagia, and hyperreflexia. Variant forms are GTP cyclohydrolase deficiency, 6-pyruvoyltetrahydropterin synthase deficiency, sepiapterin reductase deficiency, pterin-4a-carbinolamine dehydratase deficiency, and dihydropteridine reductase deficiency.

  • Tetrahydrobiopterin metabolism disorders

    Disorders in the cofactor formed from GTP, required in association with phenylalanine hydroxylase to convert phenylalanine to tyrosine. It is also involved in tyrosine hydroxylase (catecholamine synthesis) and tryptophan hydroxylase (serotonin synthesis) reactions. First described as phenylketonuria unresponsive to diet. Neonatal symptoms often include poor suck, hypotonia, microcephaly, and low birth weight, with later onset of increased salivation, pin-point pupils, sweating, oculogyric crises, seizures, myoclonus, dysphagia, and hyperreflexia. Variant forms are GTP cyclohydrolase deficiency, 6-pyruvoyltetrahydropterin synthase deficiency, sepiapterin reductase deficiency, pterin-4a-carbinolamine dehydratase deficiency, and dihydropteridine reductase deficiency.

  • TG2

    transglutaminase 2

  • TG6

    transglutaminase 6

  • TGA

    transient global amnesia

  • TGF

    transforming growth factor

  • TGIF

    5'TG3 interacting factor

  • TH

    tyrosine hydroxylase

  • Thalamic astasia

    Motor incoordination with the inability to stand or walk despite minimal weakness.

  • THCP

    trihydroxycholestanoic acid

  • Theta activity

    EEG activity with a frequency of 4-8 Hz, generally maximal over the central and temporal cortex.

  • Thiolase

    3-oxoacyl-CoA thiolase

  • THPA

    tetrahydropteric acid

  • Thr

    threonine

  • Thrombin

    An enzyme formed from prothrombin. Thrombin converts fibrinogen to fibrin, promoting clot formation.

  • Thrombophilia

    Any condition, whether inherited or acquired, that predisposes to venous or arterial thrombosis.

  • Thromboxane B2

    Metabolite of thromboxane A2, a product of platelet release reaction.

  • Thyrotropin

    Thyroid-stimulating hormone released by the pituitary gland.

  • Thyroxine

    The primary secretory product of the thyroid.

  • TIA

    transient ischemic attack

  • TICI

    thrombolysis in cerebral infarction

  • Tinel sign

    The presence of paresthesias along the distal course of a peripheral nerve elicited by sharp percussion over the injured nerve distal to the site of injury.

  • Tinel's sign

    The presence of paresthesias along the distal course of a peripheral nerve elicited by sharp percussion over the injured nerve distal to the site of injury.

  • TISH

    telencephalic internal structural heterotopia

  • Tl

    thallium

  • TLR4

    toll-like receptor-4

  • Tmax

    time to reach peak plasma drug concentraion

  • TMEM-165

    Transmembrane protein 165

  • TMJ

    temporomandibular joint

  • TMS

    transcranial magnetic stimulation

  • TNF

    tumor necrosis factor

  • Tobacco-alcohol amblyopia

    An optic neuropathy with multiple possible factors but principally exposure to cyanide and B12 deficiency.

  • Tolosa-Hunt syndrome

    Syndrome caused by inflammation of the cranial nerves that pass through the cavernous sinus.

  • TORCH

    toxoplasmosis, other, rubella, cytomegalovirus, herpesvirus

  • Torticollis

    A sustained contraction of the cervical muscles, producing twisting of the neck and an unnatural position of the head.

  • TOS

    Thoracic outlet syndrome

  • Total sleep episode

    This is the total time available for sleep during an attempt to sleep. It comprises NREM and REM sleep, as well as wakefulness. Synonymous and preferred to the term total sleep period.

  • Total sleep time

    The amount of actual sleep time in a sleep episode; equal to total sleep episode less awake time. Total sleep time is the total of all REM and NREM sleep in a sleep episode.

  • Tourette Syndrome

    A childhood-onset disorder characterized by chronic, multiple motor and vocal tics.

  • TPA

    tissue plasminogen activator

  • TPBS

    3-phase bone scintigraphy

  • Trace alternant

    EEG pattern of sleeping newborns, characterized by bursts of slow waves, at times intermixed with sharp waves, and intervening periods of relative quiescence with extreme low-amplitude activity.

  • Trail Making Test Part B

    Subjects must draw lines alternately connecting sequential numbers and letters (ie, 1-A-2-B-3-C).

  • Transcortical motor aphasia

    Impaired spontaneous speech production, but intact repetition, usually following left medial frontal cortex injury.

  • Transformed migraine

    Chronic daily headache with substantial migrainous features, or evolving out of episodic migraine. May occur with or without medication overuse.

  • Transient tic disorder

    Motor or vocal tics present with a duration of less than 1 year.

  • Transmantle pressure

    The gradient between intraventricular and subdural CSF pressure.

  • Transtentorial herniation

    Caudal displacement of the cerebral hemisphere and basal nuclei by a supratentorial (usually frontal or parietal) mass lesion, resulting in compression and rostrocaudal translocation of the diencephalon and adjoining mesencephalon through the tentorial incisura.

  • TRH

    thyroid-releasing hormone

  • Tricarboxylic acid cycle

    A mitochondrial CO2 oxidation cycle providing biochemical substrates and electrons for ATP production.

  • Trigger point

    A focus of hyperirritability in a tissue that, when compressed, is locally tender and, if sufficiently hypersensitive, gives rise to referred pain and tenderness.

  • Trigonocephaly

    A condition in which there is premature fusion of the metopic suture, resulting in a triangular shaped forehead. A bony ridge extends from the bridge of the nose to the upper part of the forehead, producing a prominent midline keel with lateral recession of the brows. From the frontal view, these patients typically have the appearance of hypotelorism or decreased distance between the eyes. Also known as trigonocephaly.

  • Triiodothyronine

    The principal active form of thyroid hormone.

  • tRNA

    transfer ribonucleic acid

  • Trophoblast

    Epithelial cover of the placental villous tree and comes in direct contact with maternal blood.

  • Trp

    tryptophan

  • True lipomas

    Lipomas that are semi-infiltrative and impossible to fully resect.

  • True myoclonic status epilepticus

    Myoclonic status epilepticus that occurs in the setting of epilepsy.

  • TSC

    tuberous sclerosis complex

  • TSC1

    tuberous sclerosis complex type 1

  • TSC2

    tuberous sclerosis complex type 2

  • TSH

    thyroid-stimulating hormone

  • TST

    The amount of actual sleep time in a sleep episode; equal to total sleep episode less awake time. Total sleep time is the total of all REM and NREM sleep in a sleep episode.

  • TTR

    transthyretin

  • TTR-FAP

    transthyretin-associated familial amyloid polyneuropathy

  • Tuberculous epidural abscess

    Spinal epidural abscess due to Mycobacterium tuberculosis.

  • tuberculous epidural abscesses

    Spinal epidural abscess due to Mycobacterium tuberculosis.

  • Tullio phenomenon

    Vertigo or nystagmus induced by loud noises.

  • Tumefactive multiple sclerosis

    Often refers to large, sometimes isolated lesions within the white matter of the cerebral cortex. Although attacks tend to cause profound axonal disruption and permanent sequellae, this problem may occur as an isolated event.

  • Tumescence

    Hardening and expansion of the penis (penile erection). When associated with REM sleep, it is referred to as a sleep-related erection.

  • Tumescence (penile)

    Hardening and expansion of the penis (penile erection). When associated with REM sleep, it is referred to as a sleep-related erection.

  • Turricephaly

    A varient of craniosynostosis where there is premature fusion of the coronal sutures, and sometimes the frontoethmoidal and sphenofrontal sutures. This results in a cone-shaped head.

  • Twinkle

    T7 gp4-like protein with intramitochondrial nucleoid localization

  • two-dimensional polyacrylamide gel electrophoresis

    In this technique, the proteins are separated in two dimensions (by isoelectric focusing and mass), and a pattern is achieved that places each of the 2000 proteins of a cell at a grid reference point. By reference to established databases, individual proteins can be identified as the product of genes that have been sequenced.

  • Type 1 Gaucher disease

    Chronic nonneuronopathic form with adult (usually adolescent) onset of symptoms of splenomegaly, jaundice, thrombocytopenia, anemia, leukopenia, and bone lesions. Type 1 represents 90% of all cases and is particularly common among Ashkenazi Jews.

  • Type 2 Gaucher disease

    Acute neuronopathic form with infantile onset of progressive hepatosplenomegaly, trismus (lockjaw), strabismus, retroflexion of the head, mental retardation, hyperreflexia, and death within 1 to 2 years.

  • Type 3 Gaucher disease

    Subacute neuronopathic form with juvenile onset of hepatosplenomegaly, ataxia, spasticity, seizures, supranuclear ophthalmoplegia, and dementia.

  • Type I acrocephalosyndactyly

    Acrocephalosyndactyly with the second through fifth digits fused into one mass with a common nail, often accompanied by moderately severe acne vulgaris on the forearms. Also known as Apert syndrome.

  • UBE3A

    ubiquitin-protein ligase

  • UDP

    uridine diphosphate

  • UFH

    unfractionated heparin

  • ULDB

    unilateral laminotomy for bilateral decompression

  • Ultradian rhythm

    A biological cycle that takes place over the course of less than a day. In human sleep, the cycle has a 90- to 120-minute duration.

  • Uncal herniation

    Inferomedial displacement of the mesial temporal lobe over the incisural edge of the tentorium by a supratentorial (usually temporal) mass lesion, resulting in compression of the mesencephalon, oculomotor nerve, and posterior cerebral artery.

  • Uncomplicated X-linked spastic paraparesis

    Spastic paraparesis resulting from a proteolipid protein gene mutation. Also known as SPG2.

  • UNE

    ulnar neuropathy at the elbow

  • Unified Parkinson Disease Rating Scale

    A system of rating parkinsonian symptoms and signs.

  • UPDRS

    Unified Parkinson Disease Rating Scale

  • UPPP

    uvulopalatopharyngoplasty

  • USPDI

    United States Pharmacopeia Drug Information

  • Utilization behavior

    Disinhibited tool or other object use.

  • UTP

    uridine triphosphate

  • UTR

    untranslated region

  • Val

    valine

  • Vasculitic neuropathies

    Peripheral nerve axonal damage resulting from a systemic vasculitic disease.

  • Vasculitic neuropathy

    Peripheral nerve axonal damage resulting from a systemic vasculitic disease.

  • Vasculitis

    Inflammation of blood vessels. The vasculitides are now categorized according to the size(s) of vessel affected by the disease.

  • Vasospasm

    Delayed narrowing of the large vessel branches at the base of the brain following subarachnoid hemorrhage.

  • VATER

    vertebral, anal atresia, tracheoesophageal fistula, radial or renal anomalies

  • VBI

    vertebrobasilar insufficiency

  • VCFS

    Velocardiofacial syndrome

  • VDRL

    Venereal Disease Research Laboratories (test)

  • Vector

    Carrier of an infectious agent from one host to another.

  • Vectors

    Carrier of an infectious agent from one host to another.

  • VEGF

    vascular endothelial growth factor

  • Velum

    Veil like structure; covering

  • Venery

    Pursuit of or indulgence in sexual pleasure.

  • Venous angioma

    Most common vascular malformation that usually remains clinically silent and is detected incidentally. These lesions may hemorrhage, cause seizure disorders, or focal deficits. They consist of one or more dilated medullary veins that drain superficially o

  • Venous angiomas

    Most common vascular malformation that usually remains clinically silent and is detected incidentally. These lesions may hemorrhage, cause seizure disorders, or focal deficits. They consist of one or more dilated medullary veins that drain superficially or deeply.

  • Ventralis intermedius of the thalamus

    Thought to act as a relay for somatosensory input from the spinal cord and cerebellum to the motor cortex. It may be an important modulator of the inherent rhythmicity of the nervous system, or may have inherent oscillations that are important in suppressing and driving tremor. It is divided into the ventralis oralis posterior, or Vop, and the ventralis intermedius, or Vim, according to Hassler terminology. In American terminology, the ventrolateral thalamic group is subdivided into the ventralis anterior, the ventralis lateralis, and the ventralis posterior.

  • Verbal fluency test

    Subjects are asked to produce as many words as possible beginning with a specified letter in 1 minute.

  • Verbigeration

    Abnormal repetition of meaningless words and phrases.

  • Vertex sharp transient

    Sharp negative potential, maximal at the vertex, occurring spontaneously during sleep or in response to a sensory stimulus during sleep or wakefulness. Amplitude varies but rarely exceeds 250 'V. Use of the term vertex sharp wave is discouraged.

  • VGCC

    voltage gated calcium channel

  • VGKC

    voltage-gated potassium channel

  • VHL

    Von Hippel-Lindau

  • Vim

    ventralis intermedius nucleus of the thalamus

  • Vimentin

    Intermediate filaments of mesenchymal cells that can be stained to identify ependymal and arachnoic cells.

  • Visual agnosia

    Seen in patients who have alexia without agraphia and color naming deficits. Patients have difficulty in recognizing and naming objects presented visually but can identify the same objects when presented by tactile or auditory stimulation.

  • Visual grasp

    Involuntary grasping elicited solely by viewing an object within reaching distance.

  • Visual paralexia

    Reading error in which the target word is misread, and the word that is substituted shares many letters with the target word.

  • VLA-4

    Very late activation antigen-4

  • VLCFA

    very long-chain fatty acids

  • VLCS

    very long-chain acyl-CoA synthetase

  • VM-26

    teniposide

  • VMA

    vanillylmandelic acid

  • VMAT-2

    vesicular monamine transporter-2

  • VNTR

    variable number of tandem repeats

  • VO2max

    maximal oxygen uptake

  • vocal tic

    Repetitive sounds or words that are produced by moving air through the nose, mouth, or throat.

  • Vocal tics

    Repetitive sounds or words that are produced by moving air through the nose, mouth, or throat.

  • VP-16

    etoposide

  • VZV

    varicella-zoster virus

  • Wada test

    Unilateral intracarotid injection of a barbiturate to identify which cerebral hemisphere is primarily involved with language, by causing temporary aphasia. The technique is done when planning neurosurgery for epileptic patients, to avoid causing postoperative aphasia.

  • WAIS

    Wechsler Adult Intelligence Scale

  • WAIS-R

    Wechsler Adult Intelligence Scale-Revised

  • Wake time

    The total time scored as wakefulness in a polysomnogram occurring between sleep onset and final wake-up.

  • Waterhouse-Friderichsen syndrome

    Fulminating meningococcal septicemia associated with adrenal hemorrhage and usually with meningitis. The clinical presentation can include vomiting, diarrhea, extensive purpura, cyanosis, meningeal signs, convulsions, and shock.

  • Waxing and waning

    A crescendo-decrescendo pattern of activity, usually EEG activity.

  • WBRT

    whole brain radiation therapy

  • Wechsler Adult Intelligence Scale

    Consists of verbal tests (information, comprehension, digit span, arithmetic, similarities, and vocabulary) and performance tests (picture arrangement, picture completion, block design, object assembly, and digit symbol), which are administered separately and completely standardized.

  • Wilcoxon matched pairs test

    This test compares two sets of observations on a single sample and is a non-parametric equivalent of the paired t test. The test calculates the difference between each observation and the value of interest. Then ignoring the signs of difference, it ranks them in order of magnitude. Finally, it calculates the sum of the negative (or positive) ranks corresponding to the observation below (or above) the chosen hypothetical value.

  • Wind-up

    A type of sensitization that occurs in dorsal horn neurons; they increase their discharge rate in response to repeated identical C-fiber stimuli spaced at intervals of 3 seconds or less. This physiologic process matches subject reports that repeated identical noxious stimulations at less than 3-second intervals causes an increase in the perceived intensity of burning.

  • WISC-III

    Wechsler Intelligence Scale for Children: 3rd edition

  • Wisconsin Card Sorting Test

    Subjects must sort cards according to three different rules-color, number, or shape. The rules by which cards should be sorted are never explicitly stated, but rather the subjects must determine the rules by trial and error based on the examiner's feedback. After consecutive successful trials using one rule, a different rule (based on the color, number, or shape of items on the cards) is implemented and the subjects must adjust their card sorting appropriately.

  • WMHI

    white matter hyperintensity

  • Word recognition

    A measure of how well a patient understands speech when it is comfortably loud enough.

  • Working memory

    A system that works in the immediate memory time domain and includes aspects of mental agility and reasoning, ie, mental manipulation, in addition to memory. A way to test working memory is to ask the patient to repeat a series of digits backwards.

  • WPPSI-R

    Wechsler Preschool and Primary Scale of Intelligence, Revised

  • WVFI

    whole ventricular field irradiation

  • X-linked aqueductal stenosis

    The most common known cause of congenital hydrocephalus in boys, characterized by hydrocephalus, macrocephaly, flexion-adduction thumb deformity, spasticity, mental retardation, and cerebral malformations secondary to a mutation in the gene for neural cell adhesion molecule L1 involved in neuroblast migration and differentiation.

  • Xanthoma

    Yellow nodules of lipid or lipoid substance.

  • Xeroderma pigmentosa

    Defects in DNA repair causing skin cancers, premature aging, and photosensitivity from ultraviolet damage.

  • XLMTM

    X-linked myotubular myopathy

  • XMTM

    X-linked myotubular myopathy

  • ZASP

    Z-disc associated alternatively spliced PDZ-domain containing protein

  • Zeitgeber

    An environmental time cue that usually helps entrainment to the 24-hour day, such as sunlight, noise, social interaction, alarm clocks.

  • zeitgebers

    An environmental time cue that usually helps entrainment to the 24-hour day, such as sunlight, noise, social interaction, alarm clocks.

  • ZFYVE26

    zinc finger FYVE domain-containing protein 26

  • ZFYVE27

    zinc finger FYVE domain-containing protein 27

  • ZNF127

    zinc ring finger protein

  • Zone of reference

    The specific region of the body at a distance from a trigger point, where the referred phenomena (sensory, motor, autonomic) that it causes are observed.