Epilepsy with myoclonic-atonic seizures (previously known as epilepsy with myoclonic astatic seizures, or Doose syndrome) is a syndrome characterized by the presence of myoclonic-atonic seizures in an otherwise normal child who may have a history of febrile and/or afebrile seizures. There is often a family history of seizures.
Clinical context: This syndrome is characterized by seizures that have onset between 6 months and 6 years of age (peak 2 to 4 years). In two thirds of children febrile seizures and generalized convulsive seizures precede the onset of myoclonic-atonic and atonic seizures. Both sexes are affected, with a male predominance (ratio 2:1). Antecedent and birth history is unremarkable. Neurological examination and head size are normal. Development and cognition are typically normal; however, impairments may develop at or after seizure onset.
Caution: Glucose transporter disorders should be excluded.
Note: Epilepsy with myoclonic-atonic seizures is considered an 'epileptic encephalopathy'. This term denotes the concept that the epileptic activity itself might directly contribute additional cognitive and behavioral impairments over those expected from the underlying etiology alone, and that suppression of epileptic activity might minimize this additional impairment.
Myoclonic-atonic seizures are mandatory seizure types to this syndrome. Atonic and myoclonic seizures are frequent. Myoclonic-atonic status epilepticus is common.
• Febrile seizures
• Absence seizures—seen in half the patients, typically with myoclonic jerks, facial myoclonia, and atonia (not just loss of awareness).
• Atypical absence seizures
• Tonic seizures are rare; the presence of tonic seizures is linked to a higher frequency of cognitive impairment.
• Generalized convulsive seizures
• Nonconvulsive status epilepticus is common, lasting for hours to days and manifests as cognitive impairment with repetitive myoclonic (affecting face, eyelids, and limbs) and atonic seizures.
• Epileptic spasms
• Focal seizures
Pattern of inheritance.
Complex (polygenic) inheritance with variable penetrance.
A minority of cases may be explained by variants in SCN1A and SLC2A1.
Family history of seizures/epilepsy.
There is frequently a family history of febrile seizures (in 50% of cases); other seizures/epilepsy syndromes may also occur in families. Epilepsy with myoclonic-atonic seizures is seen in families with other individuals with genetic epilepsy with febrile seizures plus, suggesting common genetic etiological factors.
The background may be normal or show generalized slowing. Background biparietal theta is usually seen.
Caution: Focal slowing consistently over 1 area is not seen→consider structural brain abnormality.
Generalized spike-and-wave and polyspike-and-wave occur.
Caution: Focal discharges are not seen→consider structural brain abnormality.
Intermittent photic stimulation may trigger generalized spike-and-wave and polyspike-and-wave, and myoclonic-atonic seizures.
EEG abnormality is enhanced by sleep deprivation and by sleep. Generalized spike-and-wave often becomes fragmented with sleep deprivation or in sleep. Fragmented generalized spike-and-wave can appear focal or multifocal but usually is not consistently seen in 1 area. The morphology of the focal spike-and-wave typically appears similar to the generalized spike-and-wave.
The myoclonic component is associated with a generalized spike or polyspike. The atonic component is associated with the aftergoing high voltage slow wave.
Neuroimaging is normal.
• Atypical childhood epilepsy with centrotemporal spikes
• Lennox-Gastaut syndrome
• Dravet syndrome
• Myoclonic epilepsy in infancy
• Progressive myoclonus epilepsies