Epilepsy with myoclonic-atonic seizures

Epilepsy with myoclonic-atonic seizures (EMAS), also known as Doose syndrome or myoclonic-astatic epilepsy, is a childhood-onset epilepsy syndrome characterized by the occurrence of myoclonic-atonic (myoclonic-astatic) seizures, in which a brief myoclonic jerk is immediately followed by a loss of muscle tone (atonic component), often causing the child to fall suddenly. The condition primarily affects the central nervous system and typically presents between the ages of 7 months and 6 years, with a peak onset around 2 to 5 years of age. Boys are affected approximately twice as often as girls. In addition to the hallmark myoclonic-atonic seizures, children may experience generalized tonic-clonic seizures, absence seizures, myoclonic seizures, and nonconvulsive status epilepticus. Cognitive development is often normal prior to seizure onset, but intellectual disability and developmental regression can occur, particularly in children with frequent or prolonged seizures and status epilepticus. The etiology of EMAS is believed to involve a strong genetic predisposition, with a family history of epilepsy or febrile seizures frequently reported. Several genes have been implicated in some cases, including SCN1A, CHD2, SLC6A1, SYNGAP1, and others, though in many patients a specific genetic cause is not identified. The condition is considered to have a complex or multifactorial genetic basis in most cases. EEG findings typically show generalized spike-wave or polyspike-wave discharges, often at 2–3 Hz. The treatment landscape for EMAS includes antiseizure medications such as valproic acid, ethosuximide, levetiracetam, and clobazam. The ketogenic diet has shown particular efficacy in this syndrome and is often considered early in the treatment course, especially in drug-resistant cases. Certain medications, including carbamazepine and lamotrigine, may worsen seizures and are generally avoided. The prognosis is variable: approximately half of affected children achieve seizure freedom and have favorable cognitive outcomes, while others experience refractory epilepsy with significant neurodevelopmental consequences.

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