Headache & Pain

Updated 11.20.2023
Released 03.10.1994
Expires For CME 11.20.2026

Headache associated with spontaneous spinal CSF leak

Author: Simy Parikh MD

Editor: Shuu-Jiun Wang MD

Introduction

Overview

In this article, the author reviews new concepts in spontaneous spinal CSF leak. Spontaneous spinal CSF leak can present therapeutic challenges far beyond the expected management of post-lumbar puncture CSF leaks or even post-epidural catheterization CSF leaks. This article is updated with a discussion on a nine-point brain MRI-based score that stratifies the likelihood of finding a spinal CSF leak and alternative treatments for managing spinal CSF venous fistulas.

Key points

	• Spontaneous spinal CSF leak is characterized by an orthostatic headache often accompanied by neck stiffness, tinnitus, hypacusia, photophobia, or nausea. However, leaks can also present with a second-half-of-the-day headache and, rarely, no headache.
	• The spinal location of spontaneous spinal CSF leak is important. Its pathophysiology is thought to be linked to reduced spinal dural compliance, resulting in a downward shift of the hydrostatic indifferent point and intracranial hypotension.
	• It is important not to exclude spontaneous intracranial hypotension simply because the patient experiences a nonorthostatic headache or because neuroimaging and lumbar puncture results appear normal.
	• The two main imaging tools used to localize spinal CSF leaks are fat-suppressed heavily T2-weighted magnetic resonance myelography and computed tomographic (CT) myelography.
	• The treatment of choice is an autologous epidural blood patch, preferably delivered at the level of the spinal CSF leak. Fibrin sealant injection and surgical repair are reserved for intractable cases.

Historical note and terminology

The history of how spontaneous spinal CSF leaks have been described over the years reflects clinical controversy regarding the underlying pathophysiology of this disorder.

Schaltenbrand, a German neurologist, introduced the term aliquorrhea, meaning lacking or absence of to describe a disorder associated with low, unobtainable, or even negative CSF pressures. He noted that clinically, the disorder was marked by orthostatic headache and other features (115). This description provided the first understanding of what is now known as a spontaneous spinal CSF leak.

From the 1960s to the 1990s, with the advent of radionuclide cisternography (48; 68), conventional myelography, and MRI, CSF leaks and CSF dynamics could finally be studied (112; 56; 47; 99). Imaging findings, such as venous sinus engorgement, evoked the Monroe-Kellie doctrine, suggesting that changes in these structures occurred to compensate for lack of CSF in the brain space. For this reason, in the late 1990s, spontaneous spinal CSF leak was called CSF hypovolemia or CSF volume depletion (86). However, patients were also noted to have low CSF pressure, and a competing term spontaneous intracranial hypotension emerged (28; 83). No data have ultimately supported the theory of low volume or even consistently low CSF pressure. Even the concept of the Monroe-Kellie doctrine, or the constancy of brain volume, has been challenged after a study revealed a decrease in brain tissue volume in patients with spontaneous intracranial hypotension (162).

The preferred descriptive term is spontaneous spinal CSF leak (118). This term captures the importance of the CSF leak being spontaneous or occurring with minimal or no clear precipitant. The word spontaneous is important because patients with spontaneous leaks can have a very different prognosis and workup than patients with iatrogenic and traumatic CSF leaks. The term also specifies that the CSF leak should be from a spinal source. This term is important because most people with leaks from the cranium, ie, skull-based leaks, rarely, if ever, develop symptoms or brain imaging findings consistent with spontaneous spinal CSF leak (118; 131).

Clinical manifestations

Presentation and course

A systematic review and meta-analysis of 144 publications and 53 patients showed that the most common symptoms of spontaneous spinal CSF leak were orthostatic headache (92% of patients), nausea (54%), and neck pain or stiffness (43%) (34).

Headache. An orthostatic headache that develops while sitting or standing and is relieved by assuming a horizontal position is the cardinal symptom of a spinal CSF leak (118; 31).

However, it is important to note that there is marked variability in headache characteristics. The onset of headache ranges from occurring immediately, within seconds to minutes of assuming a vertical position, to a delayed worsening after minutes or hours of being upright (31). The duration of the symptoms can affect how the symptoms present. A study showed that 93.1% of patients with less than 10 weeks of symptoms displayed typical orthostatic headache, whereas only 62.5% with more than 10 weeks of symptoms displayed typical orthostatic headache (p = 0.004) (55).

The headache onset may be acute and thunderclap-like and may, therefore, mimic headache associated with subarachnoid hemorrhage (43). In other patients, a second-half-of-the-day headache may be seen. These patients are typically headache-free in the morning, but by late morning or early afternoon, headache develops if the patient stays upright. These headaches may or may not have clear orthostatic features (90; 72).

Similarly, the onset of improvement after recumbency varies. Onset of symptom improvement, although not necessarily symptom resolution, ranges from minutes up to hours of assuming a horizontal position (31).

The quality of head pain can be described as either throbbing or non-throbbing. The location may be frontal, fronto-occipital, occipital, or holocephalic. It is often aggravated by Valsalva-type maneuvers, such as cough or strain, and is typically bilateral but sometimes unilateral.

Rarely, a paradoxical postural headache may occur and is present in recumbency and relieved in an upright position (90). Occasionally, the headaches are primarily or entirely exertional (88; 152). Of note, the emergence of a daily, persistent, non-positional pattern of head pain in the chronic stage of spontaneous CSF hypotension is concerning, as this change can suggest the development of a subdural effusion, subdural hematoma, or cerebral venous thrombosis (70; 118; 149).

Sometimes patients have no headaches at all, despite a documented CSF leak, low CSF opening pressures, or the presence of typical MRI abnormalities characteristic of the disorder (92).

Classical presentation
	Orthostatic headache Aggravated by Valsalva maneuvers Abrupt, spontaneous onset Daily after onset
Variations in presentation
	Non-orthostatic headache (20% to 25% of the time) Acephalgic (auditory symptoms predominate)
Variations in orthostatic onset
	Minutes to hours Thunderclap (within a minute) In the afternoon or evening: Second-half-of-the day

Prognosis and complications

Complications from the disorder include the development of the following comorbidities:

	(1) Subdural hematomas (2) Frontotemporal dementi (3) Nonconvulsive status epilepticus (4) Coma (5) Cerebral venous sinus thrombosis (6) Postural orthostatic tachycardia syndrome (7) Superficial siderosis (8) Bibrachail amyotrophy
(18)

In some cases, spontaneous intracranial hypotension can result in the development of chronic subdural hematomas. These hematomas are typically caused by damage to bridging veins that have been strained by brain sag (11). Patients with severe hematomas may require decompressive craniotomy, although surgery does not address the underlying cause and may necessitate repeat craniotomy (37). Conversely, resolving the underlying CSF leak typically results in the resolution of subdural fluid collections. Rarely, frontotemporal dementia, nonconvulsive status epilepticus, or coma can be caused by brain sag, obstruction of venous outflow, and swelling of the diencephalon (06; 50).

Compensatory venous engorgement and stasis resulting from a decrease in intracranial CSF volume can lead to cerebral venous sinus thrombosis. Similarly, compensatory enlargement and congestion of hypophyseal veins can cause pituitary engorgement and predispose patients to hormonal dysregulation or pituitary apoplexy.

In patients with a significant orthostatic component, prolonged supine positioning can lead to deconditioning and the development of postural orthostatic tachycardia syndrome.

Long-standing venous traction at the skull base may cause superficial siderosis and manifest as microhemorrhages, or bleeding may occur at the site of the dural defect (123).

Bibrachial amyotrophy has also been described as a long-term sequelae in chronic ventral spinal CSF leaks (126).

Clinical vignette

A 37-year-old woman presented with an acute orthostatic headache. She had no known systemic disease and had not been taking any medication regularly. She experienced an acute onset of severe headache after she got up from bed one morning 2 weeks before her presentation. It was described as a persistent dull ache in the occipital region and was associated with neck stiffness and muffled hearing. The symptoms were relieved soon after she lay supine and recurred within 5 minutes after she sat erect. There was no photophobia, phonophobia, nausea, vomiting, tinnitus, nasal congestion, or other upper respiratory tract infection symptoms, and she denied having trauma, surgery, or lumbar puncture before the onset. After unsuccessful treatment for migraine or tension-type headache by her family physician, she went to the neurology service of another hospital for help. Spontaneous intracranial hypotension was suspected, although the initial brain MRI did not show characteristic features, including no diffuse pachymeningeal enhancement. She was treated with intravenous fluids, and generous caffeine intake was recommended. There was little improvement, and she was, thus, referred to a specialist. The neurologic examination was unremarkable except for mild neck stiffness. A second brain MRI with contrast on admission revealed characteristic findings suggestive of spontaneous intracranial hypotension.

Spontaneous CSF leak imaging

A and C are axial and coronal views, respectively, of T1-weighted brain MRI with contrast 2 days after the onset of orthostatic headache. B and D are axial and coronal views, respectively, of T1-weighted brain MRI with contrast 17...

Heavily T2-weighted MR myelography demonstrated multiple CSF leaks in the cervico-thoracic junction and the upper thoracic regions. An epidural blood patch of 20 mL was delivered at the level of T1-2 and resulted in substantial improvement of her symptoms. She still had a mild to moderate orthostatic headache after the procedure. A follow-up heavily T2-weighted MR myelography demonstrated residual CSF leaks at level C7-T1, and another targeted epidural blood patch was carried out, which resulted in complete and sustained resolution of her symptoms.

This case was selected to demonstrate the following:

	• The characteristic presentation of an orthostatic headache relieved with recumbency in the absence of previous trauma or lumbar puncture should alert the physician to the possibility of spontaneous intracranial hypotension and prompt a search for spinal CSF leaks.
	• Brain MRI findings that are characteristic of spontaneous intracranial hypotension can be trivial and easily overlooked. If the initial brain MRI does not provide objective evidence supporting the clinical diagnosis, imaging procedures to demonstrate spinal CSF leaks, such as a fat-suppressed heavily T2-weighted MR myelography and CT myelography should be considered.
	• Heavily T2-weighted MR myelography is useful in localizing spinal CSF leaks. It is noninvasive and radiation-free, and it may be a good alternative to CT myelography to guide the placement of targeted epidural blood patches.

Biological basis

Etiology and pathogenesis

Spontaneous intracranial hypotension results from spontaneous spinal CSF leaks. The etiology of spontaneous spinal CSF leaks is not yet fully understood and is likely multifactorial. However, it has been linked to structural weakness of the spinal dural sac, disorders of the connective tissue matrix, CSF venous fistulas, dural tears from spinal osseous lesions, fluid-filled perineural (Tarlov) cysts, and trivial trauma (such as coughing, pushing, trivial falls and sports activities, and lifting).

The pathogenesis of orthostatic headache secondary to spontaneous intracranial hypotension is also unclear, and theories regarding this concept are evolving over time. Ultimately, the thought is that spinal CSF leaks cause orthostatic headache by disrupting craniospinal CSF space elasticity or compliance (74). Specifically, when the lumbar spinal CSF space compliance abnormally increases, the hydrostatic indifferent point, or the point at which venous pressure is not affected by posture, is displaced caudally. This caudal displacement of the hydrostatic indifferent point leads to acute orthostatic venous distention on position shift from recumbency to sitting or standing, thereby producing an orthostatic headache.

Of note, the theory that depletion of CSF volume is the sole cause of spontaneous intracranial hypotension or orthostatic headache is controversial. Patients with CSF rhinorrhea or otorrhea, conditions that also cause CSF volume depletion, rarely, if ever, develop symptoms or brain imaging findings typical of spontaneous intracranial hypotension (118). Therefore, even in the presence of cranial CSF leaks, a spinal source should be sought in patients with orthostatic headaches thought to be secondary to spontaneous intracranial hypotension (131).

Table 1. Proposed Mechanisms of Clinical Manifestations in Spontaneous Spinal CSF Leak

(1) Headaches	Orthostatic headaches are secondary to traction on pain-sensitive cranial nerves (V, IX, X) and acute orthostatic venous distention on position shift from recumbency to sitting or standing (74).
(2) Diplopia	Diplopia results from stretching or compression of the related cranial nerves (46; 54).
(3) Visual blurring and visual field cuts	Visual changes result from compression or vascular congestion of the intracranial portion of the optic nerve (58).
(4) Dizziness and change in hearing, decreased hearing, deafness, tinnitus, orthostatic tinnitus	Hearing and vestibular changes are due to stretching of cranial nerve VIII or pressure changes in the perilymphatic fluid of the inner ear (106; 97).
(5) Galactorrhea and increased serum prolactin level	Increased prolactin can happen due to distortion of the pituitary stalk as a result of sinking of the brain (163)
(6) Radicular upper limb symptoms	Radicular upper limb symptoms occur due to stretching of the cervical nerve roots due to sinking and downward displacement of the brain or irritation of the nerve root by dilated epidural venous plexus (03; 90).
(7) Encephalopathy, stupor, and coma	Mental status changes are attributed to diencephalic compression (10; 104; 42).
(8) Cerebellar ataxia and parkinsonism and bulbar manifestations	Cerebellar and motor symptoms are attributed to posterior fossa compression and deep mid-line structures (98).
(9) Frontotemporal dementia	Frontotemporal-like dementia is attributed to the compression of frontal and temporal lobes (57; 158).
(10) Gait disorder	Gait disturbances are attributed to spinal cord venous congestion (96), cord distortion, or deformation (84; 159).

Table 2. Mechanisms of MRI Abnormality

Spontaneous spinal CSF leak leads to the following:
	(1) Collapse of the ventricles, which may be obvious or subtle.
	(2) Sinking of the brain that, on MR imaging, is manifested by descent of the cerebellar tonsils (sometimes mimicking Chiari I malformation), a decrease in the size of the prepontine and perichiasmatic cisterns, flattening of the optic chiasm, and crowding of the posterior fossa.
	(3) Intracranial venous hypervolemia and subdural fluid collections. According to the Monro-Kellie Doctrine (87), given the fact that an intact skull is not compressible and that the brain is not expected to expand, loss of CSF volume has to be somehow compensated. This is accomplished by engorgement of cerebral venous sinuses and dilation of meningeal veins. The latter is the cause of diffuse pachymeningeal enhancement. Engorgement of the pituitary vessels is responsible for pituitary enlargement.
	(4) Another consequence of CSF volume depletion is a partial collapse of the spinal dura, which in turn leads to a compensatory dilation of epidural venous plexus (74).

Differential diagnosis

Unfortunately, our knowledge of the true incidence and prevalence of the disorder is affected by misdiagnosis. It has been found that up to 94% of individuals with spontaneous intracranial hypotension have been misdiagnosed, with the most common misdiagnoses being migraine, meningitis, psychological disorders, or even malingering (117).

Differential diagnosis for orthostatic symptoms. A patient presenting with a chief complaint of an orthostatic headache relieved with recumbency should alert the physician to the possibility of spontaneous intracranial hypotension.

The differential for orthostatic headache or symptoms includes:

(1) Postural orthostatic tachycardia syndrome (93)
(2) Orthostatic hypotension (18)
(3) Cervicogenic headache (18)
(4) Migraine (18)
(5) Postdural puncture headache, traumatic CSF venous
(6) Mass lesions that affect craniospinal pressure

POTS usually manifests as orthostatic tachycardia with minimal orthostatic blood pressure change and can be either comorbid or separate from spontaneous spinal CSF leak. Orthostatic hypotension presents with orthostatic symptoms; this disease manifests with a fall in systolic (20 mmHg) or diastolic (10 mmHg) blood pressure on standing from a seated or supine position. These diseases are distinguished from spontaneous spinal CSF leaks in patients with stable heart rate or blood pressure during transition from supine to sitting to standing (18). Cervicogenic headache manifests with neck pain that worsens with cervical motion and can be improved with medication or facet blocks. Migraine can also present with orthostatic vertiginous symptoms, but patients typically have a history of headache or migraine, and symptoms can be alleviated with antimigraine medications.

In the setting of recent spinal procedures or trauma, the differential diagnosis also includes postdural puncture headache and traumatic CSF venous fistula. A careful patient history should elicit causal events.

Other conditions that affect craniospinal pressure should also be considered, including intracranial neoplasms, colloid cysts, and cerebral venous thrombosis (37).

Differential diagnosis for new daily headache. Spontaneous intracranial hypotension should be part of the differential diagnosis of any new-onset daily persistent headache (116; 117; 37).

Confusing conditions

One notable confusing condition is Chiari type I malformation. Like spontaneous spinal CSF leak, imaging findings of Chiari type I malformation show descent of the cerebellar tonsils, and patients can have headache (typically cough-induced) and other neurologic symptoms (18). Patients who have spontaneous spinal CSF leak and who are mistakenly diagnosed with and treated for Chiari type I malformation with surgical posterior fossa decompression can have worsening symptoms. Therefore, distinguishing these disorders is important.

A Chiari type I malformation occurs in less than 1% of the general population; it is typically asymptomatic and is associated with abnormal morphology at the craniocervical junction (18). In patients with spontaneous spinal CSF leak, cerebellar tonsils do not typically descend more than 5 mm below the foramen magnum and will also typically be accompanied by descent of the midbrain, fall in the cerebral aqueduct (iter) beneath the incisural line, and other signs of brain sag (18). The presence of a syrinx is more likely in Chiari type I malformation. The descended tonsils in Chiari type I malformation typically take on a peg-shaped appearance.

Associated or underlying disorders

Because the development of spontaneous intracranial hypotension has been linked to the following disorders, investigation for these concomitant disorders may be warranted. Importantly, there is no causal association between spontaneous intracranial hypotension and cranial cerebrospinal fluid leaks (131).

(1) Disorders of the connective tissue matrix
(2) CSF venous fistulas
(3) Dural tears from spinal osseous lesions
(4) Perineural (Tarlov) cysts

Underlying disorders of connective tissue matrix are thought to cause dural weakness and, thereby, may be risk factors for spontaneous CSF leaks (114; 102). Although the presence of underlying well-characterized connective tissue syndromes is rare (less than 5%), physical skeletal characteristics suggestive of systemic connective tissue matrix disorders, such as Marfanoid features, hypermobile joints, and hyper-extensible skin, have been found in up to two-thirds of patients (88; 121). Specifically, in comparing clinical features of patients with connective tissue disorders and spontaneous intracranial hypotension with controls with connective tissue disorders but without spontaneous intracranial hypotension, dolichostenomelia (disproportionately long limbs), but not the other above-mentioned stigmata, was more common (78). Although patients with these skeletal manifestations and spontaneous intracranial hypotension have been found to have abnormalities in fibrillin-1 metabolism, a genetic link to Marfan syndrome has yet to be demonstrated (132). It has been shown that most patients do not harbor mutations in FBN1 gene, encoding fibrillin 1, or in TGFBR2 gene, encoding transforming growth factor-beta receptor 2 (132; 27; 120).

New investigations have shed light on spontaneous CSF-venous fistulas leading to CSF leaks. Dilated epidural veins and arachnoid granulations can contribute to the development of a spontaneous CSF-venous fistula, which serves as a direct conduit for outflow from the subarachnoid space into the systemic circulatory system via spinal epidural veins, thereby causing spontaneous intracranial hypotension (124). CSF-venous fistulas should be suspected in patients with refractory spontaneous intracranial hypotension and unremarkable conventional spinal imaging. Digital subtraction myelography, and even CT myelography, may be useful in diagnosing this underlying pathology (124; 66).

A dural tear from a spondylotic spur (148; 41; 17) or disc herniation (160; 109) may cause a dural defect and CSF leak. Microsurgical exploration has led to the discovery of discogenic microspurs as underlying pathology for CSF leaks from primarily ventral dural tears. Up to 71% of cases with intractable spontaneous intracranial hypotension were found to be secondary to a CSF leak from a circumscribed vertical longitudinal slit in the dura caused by a calcified microspur originating from an intervertebral disc (12).

Perineural (Tarlov) cysts, or cysts filled with CSF located between the nerve root and dorsal ganglion, can occur in multiple locations in the spine and cause CSF leaks (108). Tarlov cysts should be suspected in patients with concomitant symptoms of back pain, radicular pain, or bowel or bladder dysfunction (108). CT myelogram is diagnostic, and treatment of the cysts with blood patching, surgical excision, or percutaneous drainage may resolve symptoms (108).

Diagnostic workup

The ICHD-3 requires either a low CSF pressure (less than 6 cm H20) or radiological (spine or brain) evidence of spinal CSF leak for the diagnosis of spontaneous intracranial hypotension (31). However, patients with spontaneous intracranial hypotension can commonly have normal CSF pressures, suggesting that a lack of low CSF pressure should not exclude this condition (67; 151; 37). In addition, obtaining a CSF pressure with lumbar puncture may worsen the symptoms of someone with a spontaneous spinal CSF leak. Fortunately, a correct diagnosis can usually be made based on characteristic clinical presentation and typical findings on noninvasive MRI techniques, and the need for a spinal tap has been greatly reduced.

Overall, a head CT scan is of little help in diagnosing this disorder, as it typically will not reveal abnormalities characteristic of spontaneous intracranial hypotension. Sometimes subdural fluid collections or increased tentorial enhancement may be seen (101; 136).

Common MRI brain imaging abnormalities. Magnetic resonance imaging has truly revolutionized the diagnosis and follow-up of patients with spontaneous intracranial hypotension. It is important to note that MRI brain imaging findings can be normal in patients with spinal CSF leaks (34). A meta-analysis estimated normal brain MRI imaging findings in 19% of patients (34). However, when brain MRI imaging findings are present, typical findings in spontaneous intracranial hypotension include:

(1) Diffuse pachymeningeal enhancement (2) Imaging evidence of brain sag
	Descent of the cerebellar tonsils Decrease in the size of prepontine or perichiasmatic cisterns Crowding of the posterior fossa
(3) Engorgement of cerebral venous sinuses (4) Subdural fluid collections (5) Enlargement of the pituitary gland (6) Decrease in the size of the ventricles (7) Elongation of the brainstem in the anteroposterior plane (8) Collapse of superior ophthalmic veins

In a retrospective analysis, pachymeningeal enhancement, signs of brain sag, and venous distension sign were the most common MRI brain abnormalities correlating with low spinal CSF pressure, present in 83%, 61%, and 75% of subjects, respectively (67).

A new method for diagnosing spontaneous intracranial hypotension involves a nine-point brain MRI-based score (37; 38). This scoring system categorizes the probability of detecting a spinal CSF leak in individuals who are clinically suspected of having spontaneous intracranial hypotension (37; 38). The scoring system includes three major indicators and three minor indicators. The three major indicators, each worth 2 points, include pachymeningeal enhancement, venous sinus engorgement, and suprasellar cistern effacement (measuring 4.0 mm or less). Three minor indicators, which are worth 1 point each, include the presence of subdural fluid collection, effacement of the prepontine cistern (measuring 5.0 mm or less), and a decrease in the mamillopontine distance (measuring 6.5 mm or less). The total score ranges from 0 to 9, with 0 indicating low probability and 9 high probability of spinal CSF loss. The score required to accurately identify patients with a high probability of a CSF leak (score of 5 or above) has a specificity of 81.8% and sensitivity of 88.9%. However, there is no established cutoff score for spontaneous intracranial hypotension. It is worth noting that some patients with confirmed spinal CSF leak exhibit no abnormalities on brain MRI.

There is a direct correlation between disease duration and neuroimaging findings. A study of 173 patients with spontaneous intracranial hypotension and an average 3-week duration of symptoms showed that patients with a shorter onset-neuroimaging interval (fewer than 17 days) had a lower probability of being classified as high probability (score 5 or greater). However, the patient cohort of shorter duration symptoms still had a similar probability of having a neuroimaging score of 3 or greater between onset-neuroimaging intervals of fewer than 17 days and 17 days and greater, indicating the brain MRI-based score is sensitive even in shorter symptom-duration cohort (21).

Diffuse pachymeningeal enhancement (sparing the leptomeninges), thought to be secondary to increased transmural venous pressure causing dilation of inner dural veins (74), is the most common MRI abnormality. It is diffuse, uninterrupted, and non-nodular, and it involves the supratentorial and intratentorial pachymeninges. Typically, it appears thick and obvious on imaging but sometimes is thin (56; 47; 99).

Pachymeningeal enhancement

Pachymeningeal enhancement in patients with spontaneous spinal CSF leak, as demonstrated in this coronal MRI brain with gadolinium enhancement, is diffuse, uninterrupted, and non-nodular, and it involves the supratentorial and ...

Sinking of the brain, sagging, or descent of the brain is manifested by the descent of the cerebellar tonsils mimicking a type I Chiari malformation, as well as sinking of the opening of the third ventricle aqueduct (iter) to a level below the incisural line (61; 76). Furthermore, descent of the brain may lead to a decrease in the size of the prepontine and perichiasmatic cisterns, crowding of the posterior fossa, inferior displacement, and flattening of the optic chiasm. It is proposed that decreased mamillopontine distance (< 5.5 mm) and reduced pontomesencephalic angle (< 50˚) may provide supportive clues for diagnosis (135).

Crowding of the posterior fossa

Crowding of the posterior fossa manifests by narrowing of the prepontine space (orange arrow), flattening of the pons (black arrow), and decrease of the mamillopontine distance (blue arrow). Tonsillar ectopia is noted by the green...

Engorgement of cerebral venous sinuses is frequently noted (09). The venous distension sign, distension of the midportion of the dominant transverse sinus with a convex appearance on T1-weighted sagittal MRI, is useful in detecting intracranial hypotension (44). A study showed that convex margins of the transverse sinuses, but not concave margins, predicted an association between midbrain pons angle (within brain descent cluster) and spinal cerebrospinal fluid leak severity (161). Superior sagittal venous engorgement can also be seen on coronal T1-weighted MRI brain imaging after gadolinium injection (37). The venous distension sign has been shown to be a sensitive marker of spontaneous intracranial hypotension, with a greater than 75% incidence regardless of disease duration (21).

Venous engorgement of the superior sagittal sinus

The red box indicates venous engorgement of the superior sagittal sinus in a patient with a spontaneous spinal CSF leak. (Contributed by Dr. Simy Parikh.)

Enlargement of the pituitary gland can be obvious and may mimic pituitary adenoma or pituitary hyperplasia (04). This enlargement is due to hyperemia (increase in blood flow) in the pituitary gland and is linked to hyperemia of the dural and epidural venous sinuses. Increased pituitary gland height (mean ± SD, 6.9 ± 2.3 mm) has a sensitivity of 63% and specificity of 97% of spontaneous spinal CSF leak. This finding is reversible and, with resolution or management of the disease, resolves earlier than meningeal enhancement.

Subdural fluid collections are typically bilateral but may be unilateral and appear over the cerebral convexities. These fluid collections are usually hygromas that may reveal variable signal intensity depending on the concentration of protein in the fluid, although subdural hematoma may sometimes develop and cause significant mass effects (70).

Ophthalmic findings. There are additional ophthalmic findings that correlate with spontaneous spinal CSF leak. The diameter of the superior ophthalmic vein on contrast-enhanced T1-weighted coronal MRI was reported to be correlated with intracranial pressure (77), and collapsed superior ophthalmic veins might provide additional clues for intracranial hypotension (22). Decreased intersheath space of the optic nerve also has been reported and probably also results from reduced CSF content (111), and a similar finding has been demonstrated with sonography (39).

Common spinal MRI imaging abnormalities. It is important to note that MRI spine imaging findings can be normal in patients with spinal CSF leak (34). However, when they are present, conventional spinal MRI abnormalities include the following:

(1) Extra-arachnoid or epidural fluid collections
(2) Meningeal diverticula
(3) Spinal pachymeningeal enhancement
(4) Engorgement of spinal epidural venous plexus

Extra-arachnoid or epidural fluid collections, when present, indicate the presence of CSF leakage (25). However, such fluid collections often extend across several levels and, thus, do not reveal the exact site of the CSF leakage (38).

Spinal epidural fluid collection

The red box indicates epidural fluid collection in a heavily T2-weighted fat-suppressed spinal MRI. (Contributed by Dr. Simy Parikh.)

Extravasation and extension of fluid into the paraspinal soft tissues are infrequently seen and may represent the actual location of CSF leakage. However, when these are seen in the high retro-cervical region, it is claimed that they may not represent the actual site of the leak and may be a false localizing sign (128).

Spinal pachymeningeal enhancement may also be seen, although not as frequently as intracranial pachymeningeal enhancement (85).

Engorgement of epidural venous plexus may be seen at any level of the spine, but typically it is more prominent in mid-thoracic and low thoracic as well as lumbar levels (20; 25). Generally, although a conventional spinal MRI is helpful in revealing abnormalities that might suggest a CSF leak, it is only occasionally that it reveals the actual site of the leakage of the CSF.

Localization of the CSF leak is important as patients refractory to nontargeted therapy may need to undergo targeted epidural injections or surgical repair. However, CSF leak localization can be difficult and is somewhat dependent on leakage rate. Therefore, there continues to be development of imaging modalities and algorithms to aid in targeting the location of the CSF leak.

Heavily T2-weighted, fat-suppressed, MR myelography is a noninvasive MRI technique useful in localizing spinal CSF leaks and has emerged as a good alternative to invasive imaging techniques, such as CT myelography, in the diagnosis and follow-up of patients with spontaneous intracranial hypotension (150; 62; 141; 63). This imaging requires neither lumbar puncture nor contrast medium administration. The principle of heavily T2-weighted MR myelography is to exaggerate the contrast between the signal of CSF, which appears bright, and those from other tissues, which are either invisible or barely visible. Unlike that on conventional spinal MRI, extravasated CSF in heavily T2-weighted MR myelography is readily discerned from the background. Axial slices throughout the entire spine can provide excellent spatial resolution comparable to CT myelography. It is also a time-efficient technique, for a single-shot fast spin-echo pulse sequence is used, and the entire spine can be imaged in both axial and longitudinal planes within 15 minutes (141). As in CT myelography, heavily T2-weighted MR myelography can demonstrate indirect signs of three major types of CSF leakages.

(1) CSF leaks along the nerve roots: These are the presumed location of dural defects. Extravasated CSF leaks out of the spinal canal along the nerve roots and at times extends into the paraspinal soft tissues. The leaks appear as bright signals extending from the flanks of sunny side up, which represent signals from the intradural CSF and the cord through the neuroforamina. They assume a band- or thread-like appearance and sometimes look like a fimbria, spreading out at the end. They are most commonly seen in the cervicothoracic junction or the upper thoracic spine, and multiple leaks are not uncommon. Of note, as apparent CSF collections at the cervicothoracic junction is often a false localizing sign, the clinician must be cautious when evaluating CSF in this area (122).

(2) Epidural CSF collections: Some of the extravasated CSF stays within the spinal column and appears as bright signals alongside the periphery of the sunny side up. Epidural CSF collections usually extend for several spinal segments and are not necessarily located in the vicinity of CSF leaks along the nerve roots. The distribution might represent compliance with gravity and can be misleading in localizing the actual location of dural tears.

(3) High-cervical extraspinal CSF collections: They appear as patchy bright signals, which may be confluent or scattered, outside the spinal canal in the high cervical region. They are mostly on the dorsal side of the sunny side up, but occasionally, extension to the lateral or even ventral side can be seen. These are well-known false localizing signs and have nothing to do with the actual leakage sites.

Most periradicular postlumbar puncture CSF leaks found on heavily T2-weighted MR myelography have been demonstrated to occur within three segments of the lumbar puncture. This suggests that dural defects associated with spontaneous intracranial hypotension may be near periradicular leaks found on heavily T2-weighted MR myelography (155).

It has been demonstrated that heavily T2-weighted MR myelography was comparable to CT myelography in localizing spinal CSF leaks and was a good alternative to CT myelography before targeted epidural blood patching. However, its applicability for other targeted treatments, such as injection of fibrin sealant or surgical repair, is yet to be determined (142; 156).

CT myelography findings. CT myelography has been the gold standard in localizing spinal CSF leaks (38). This test may show the following:

Extra-arachnoid leakage of fluid
Extradural extravasation of contrast (and, therefore, CSF) and its extension into the paraspinal soft tissues
Meningeal diverticula
The actual site of the CSF leakage

Conventional CT myelography is performed by myelogram with water-soluble contrast, followed by CT scanning. Slices are typically obtained at each spinal level or at a more selected region if the myelogram itself or a previous cisternography or spinal MRI has revealed clues for potential leakage sites. Under typical circumstances, one would expect to locate the site of the CSF egress and CSF leakage. However, the rate of leakage of CSF may provide special challenges.

Delayed CT myelography may be helpful for slow-flow leaks. Dynamic CT myelography may allow the detection of high-flow leaks (73; 79). Ultrafast dynamic CT myelography was found to be especially helpful in identifying CSF leaks caused by spinal osteophytes (140). To reduce multiple and unnecessary tests, Verdoon and colleagues found success in reducing the need for repeat CT myelograms by using the presence of extradural fluid on spinal MRI to direct whether a patient should have a dynamic CT myelography for CSF leak localization, rather than first undergoing a conventional CT (146).

Radionuclide cisternography findings. Radionuclide cisternography, involving intrathecal injection of indium-111, was previously frequently used, but is now rarely used, in establishing a diagnosis of CSF leak. The dynamics of injected radionuclide are followed by subsequent scanning at various intervals of up to 24 or 48 hours. Normally, by 24 hours, but often earlier, abundant radioactivity is detected over the cerebral convexities. When there is CSF leakage, the radioactivity often does not extend much beyond the basal cisterns. Therefore, on 24-hour or 48-hour images, there is the absence or paucity of activity over the cerebral convexities (95; 13; 08). A more desirable but much less common abnormality is detection of parathecal or paradural activity, pointing to the site or approximate level of CSF leak. Meningeal diverticula may assume a similar appearance and can be confused with actual leakage sites. Multiple parathecal radioactivities do not necessarily correspond to multiple spinal CSF leaks (90). Another cisternographic finding in CSF leaks is the early appearance of radioactivity in the kidneys and urinary bladder (59). Normally, such activity is noted at 6 to 24 hours after the intrathecal introduction of radioisotope. When there is a CSF leak, activity in the kidneys and urinary bladder may be seen in less than 4 hours.

Digital subtraction myelography. Digital subtraction myelogram is a myelogram done under fluoroscopy; the precontrasted image is digitally subtracted to enhance the visualization of the contrast. This imaging technique is useful to detect rapid leaks, ventral leaks, and leaks not associated with an obvious extrathecal CSF collection, such as a CSF venous fistula (130). Consecutive-day right and left lateral decubitus digital subtraction myelography may be beneficial in detecting CSF venous fistulas (105).

Contrast-enhanced MR myelography. Contrast-enhanced MR myelography or gadolinium-enhanced MR cisternography involves obtaining an MRI of the spine after intrathecal gadolinium administration; immediate and delayed images are obtained. This technique is debated; by some, it is considered helpful in detecting the so-called slow-flow leaks (139; 02). It has been considered by some to be sensitive and accurate enough to be an alternative to CT myelography (145). However, a retrospective study showed that contrast-enhanced MR myelography does not improve the diagnostic accuracy for the detection of epidural CSF and should not be included in the workup (38).

It should be noted that no gadolinium-containing contrast medium has been approved for intrathecal use, but the use of intrathecal normal saline followed by intrathecal gadolinium infusion has been studied. Intrathecal preservative-free normal saline challenge followed by contrast-enhanced MR myelography was shown to be a technique with the potential to increase detection of slow-flow CSF leaks (53).

Complications of invasive imaging. Challenges to invasive imaging include radiation exposure and the development of iatrogenic CSF leaks. Radiation exposure is a concern for radionuclide cisternography and CT myelography, especially for the latter. For patients receiving dynamic CT myelography, which involves multiple scans, the dose of radiation is even higher. The cumulative risk of oncogenicity should be carefully weighed against the benefits because most of these patients are young or middle-aged adults with a considerable life expectancy (14; 137). One study reported evidence of iatrogenic lumbosacral CSF leakage on MR myelography after radionuclide cisternography in a substantial proportion of patients (113). The results indicated that iatrogenic CSF leaks could be a potential pitfall for imaging studies involving a lumbar puncture, such as radionuclide cisternography and, perhaps, CT myelography and gadolinium-enhanced MR myelography/cisternography. Intrathecal gadolinium-based contrast agents can be tolerated at low doses, but doses over 1.0 mmol can cause severe neurologic symptoms, including seizures, confusion, neurologic deficits, and changes in mental state (100).

Management

Conservative treatment. Various treatment modalities have been advocated for patients with spontaneous CSF leaks. These are based on prior experience with post-lumbar puncture headaches rather than direct experience with spontaneous CSF leaks. These include the following:

Bedrest
Caffeine
Theophylline
Abdominal binder
Occipital nerve block

However, conservative management should only be employed as a temporary measure while the patient is waiting for more definitive treatment (151). According to a small retrospective study on patients with spontaneous intracranial hypotension who underwent conservative treatment, over 50% of them continued to experience symptoms even after 6 months. Furthermore, approximately one third of the patients still reported symptoms even after 2 years (64). Another study showed that up to 81% of patients required an epidural blood patch due to the failure of symptom management with supportive measures only (29).

Epidural blood patches. Autologous epidural blood patch has emerged as the treatment of choice for those patients who fail initial conservative management (52; 36; 32; 138; 133; 15), and it has been suggested that early epidural blood patching is helpful in the majority of patients (15; 81). The effect of an epidural blood patch is essentially two-fold. The immediate effect may be related to increased pressure in the epidural space, leading to decreased compliance (74). The latent effect is related to the sealing of the dural defect by triggering a focal tissue reaction (40). Sometimes, the patient may obtain a near-immediate and lasting effect soon after the procedure. On the other hand, some patients note an almost immediate improvement followed by the recurrence of symptoms and then a latent improvement after a few days or weeks. Moreover, repeated large-volume epidural blood patches may be necessary to relieve symptoms on rare occasions (82).

Overall, the efficacy of an untargeted epidural blood patch in spontaneous CSF leaks is approximately 29% to 35% (134; 103). A study of 51 patients with spontaneous spinal CSF leak showed that 71% had a persistent spinal CSF leak after an untargeted epidural blood patch on postinterventional imaging or intraoperatively (103). The authors estimated that the success rate of sealing a spinal CSF leak with an untargeted blood patch was 29% (103).

This efficacy rate is less satisfactory in patients with spontaneous intracranial hypotension than in those with intracranial hypotension syndrome following lumbar puncture or epidural or spinal anesthesia (147). This discrepancy is likely attributed to the fact that epidural blood patches are delivered exactly to the site or the vicinity of the dural defects in treating post-lumbar puncture headaches, whereas in spontaneous intracranial hypotension, the blood patches are usually delivered blind at the lumbar region instead of the CSF leakage sites, especially when the CSF leaks could not be localized. In addition, the anatomy of dural defects in spontaneous intracranial hypotension is more complex.

Evidence suggests that targeted epidural blood patches, or patches placed directly at the level of identified spinal CSF leaks, may double the response rates as compared to traditional, nontargeted lumbar epidural blood patches (134; 156; 26). Moreover, improvements have been made in needle placement technique to target the ventral epidural space (05).

An SIH-EBP score has been developed using a cohort of 280 patients. The score identified the variables of age greater than 50 years, female gender, midbrain pons angle of 40° or more, and anterior epidural CSF collection of fewer than 19 segments as positive predictors of a response to the first epidural blood patch (75). Although this score needs to be further studied in a multi-institutional setting, such a score can aid the prognosis of outcomes to a first epidural blood patch in patients with spontaneous intracranial hypotension.

With more understanding as to concomitant conditions leading to CSF leaks, the advent of noninvasive heavily T2-weighted MR myelography, and the development of new placement techniques, targeted epidural blood patches may be considered as the first-line treatment directed at the identified spinal CSF leaks in the hope of hastening recovery and limiting the development of complications; however, more studies are needed before the spectrum of applicability is determined.

Reports on epidural injections of fibrin glue and fibrin sealant are encouraging (49; 33; 125), especially for patients who failed epidural blood patching. However, there have been two patients experiencing anaphylactic reactions after fibrin sealant injection in treating spontaneous intracranial hypotension (119).

Epidural infusion of saline has produced various results (110; 144; 51). One might consider this with limited expectations in some of the patients who have failed epidural blood patches and when other measures such as epidural injection of fibrin glue or surgery are not viable options.

Similarly, the experience with intrathecal fluid infusion in spontaneous CSF leaks is limited. However, on the rare occasions that patients show obtundation or impending coma, this technique may prove helpful in improving the level of consciousness and allowing time to search for the site of the leak and establish a more definitive treatment if no lasting effect is obtained (16; 157). One would be concerned about potential complications of continuous epidural or intrathecal infusions, such as infection.

Surgery in well-selected cases often proves helpful. It may be considered in those patients who have failed less invasive treatment modalities. Neuroradiological studies must determine the actual site of the CSF egress before surgery is undertaken. Because the anatomy of the spontaneous leak may be complex, the surgery may not always be straightforward. Sometimes, a surgeon may encounter the leaked CSF but may not be able to locate the exact site of the leak. In this type of case, he or she may pack the area with blood-soaked gel foam, muscle, etc. and hope for the best. Sometimes, dural defects are encountered with so markedly attenuated a border that it may not yield to suturing. Other times, meningeal diverticula or dural defects are encountered that surround one or more nerve roots and create technical challenges (129). It has been reported that minimally invasive surgery to correct the leaking meningeal diverticulum may be considered an alternative to conventional open surgical repair, although it is yet to be determined whether this approach is feasible for most patients (45).

Cerebrospinal fluid-venous fistula has been described as a refractory cause of spontaneous intracranial hypotension. A prospective study found that surgical ligation is highly effective for the treatment of spontaneous intracranial hypotension due to cerebrospinal fluid-venous fistula (153). Transvenous onyx embolization of their CSF-venous fistulas and transarterial particle embolization of the bilateral middle meningeal arteries as a treatment for CSF venous fistulas is a reported alternative procedure to ligation (80). Given the recency of recognizing and managing CSF venous fistulas, the comparative long-term prognoses of these procedures are unknown.

Outcomes

In a 2021 cross-sectional, web-based survey of multiple healthcare professional groups in the United Kingdom, respondents noted obstacles to treating spontaneous intracranial hypotension, such as a shortage of myelography experts, limited access to epidural blood patches, and no established management pathways (19). However, once treated, patients with spontaneous CSF leaks can completely recover. Many require invasive therapeutic approaches, such as an epidural blood patch, epidural injection of fibrin glue, or even surgery. Recurrences may occur at variable rates based on the treatment approach.

Predictors of autologous epidural blood patch success have been studied. Structural factors such as brain sagging on imaging, severe diencephalic-mesencephalic deformity, and intracranial structural dislocation, as measured by the angle between the vein of Galen and sagittal sinus, have been found to be negative predictors of clinical response from the first epidural blood patch (60; 30; 161). Early visualization of bladder activity in radioisotope cisternography was also found to be a negative predictor of success (60). This is thought to be a marker of increased CSF leakage, leading to increased release of the radioactive tracer into systemic circulation, causing early appearance in the bladder.

A major complication of spontaneous CSF leak is the development of unilateral or bilateral subdural hematomas. As many as 20% of patients may develop subdural hematomas, which may be asymptomatic, or they can increase in size, becoming symptomatic and creating significant therapeutic challenges (07; 35; 107; 143; 70). Size of the subdural hematoma is important (23).

Patients with spontaneous intracranial hypotension and subdural hematomas that are less than 10 mm can be treated conservatively or with an epidural blood patch with good outcomes. However, patients with spontaneous intracranial hypotension and subdural hematomas more than 10 mm in size may be at risk for uncal herniation (23), which can result in bilateral posterior circulation infarcts and Duret hemorrhage (35; 24). Patients with spontaneous intracranial hypotension and subdural hematomas greater than 10 mm in size should have their Glasgow Coma Scale (GCS) scores closely monitored. In patients with decreased GCS scores, early surgical evacuation might prevent uncal herniation and prevent poor outcome (23).

Cerebral venous thromboses reportedly occur in about 2% of patients with spontaneous intracranial hypotension, and the majority (about 85%) involve dural venous sinuses (15; 118). Isolated cortical vein thrombosis has also been reported in spontaneous intracranial hypotension (69; 71; 154), as well as in intracranial hypotension syndrome following unsuccessful epidural anesthesia (01). These patients may have a change in headache pattern (40%), venous infarction, seizure, dural arteriovenous fistula, or even cortical subarachnoid hemorrhage.

Sometimes following treatment of spontaneous CSF leaks, whether by surgery or by epidural blood patch, a symptomatic syndrome of rebound intracranial hypertension may develop (89; 65). This is usually a self-limiting syndrome that resolves within several weeks or months.

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Headache associated with spontaneous spinal CSF leak

Associated Disorders

Connective tissue matrix disorders
Klippel-Trenaunay syndrome

Differential Diagnosis

orthostatic headache
postural orthostatic tachycardia syndrome
orthostatic hypotension
cervicogenic headache
migraine
- intracranial hypotension
- dural puncture
- subarachnoid hemorrhage
- meningitis
- idiopathic Chiari I malformation
- foramen magnum tonsillar herniation
- pituitary tumor
- tension-type headache
- cerebral venous sinus thrombosis
- new daily persistent headache
- postural tachycardia syndrome
- CSF-venous fistula

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Headache & Pain

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Tarlov cysts

Headache associated with spontaneous spinal CSF leak

Introduction

Overview

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Historical note and terminology

Clinical manifestations

Presentation and course

Prognosis and complications

Clinical vignette

Biological basis

Etiology and pathogenesis

Table 1. Proposed Mechanisms of Clinical Manifestations in Spontaneous Spinal CSF Leak

Table 2. Mechanisms of MRI Abnormality

Epidemiology

Prevention

Differential diagnosis

Confusing conditions

Associated or underlying disorders

Diagnostic workup

Management

Outcomes

Media

References

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