Epilepsy with myoclonic absences

Epilepsy with myoclonic absences is characterized clinically by absences accompanied by marked, diffuse, rhythmical myoclonias, often associated with a progressive tonic contraction. The ictal EEG shows bilateral, synchronous and symmetrical spike and wave discharges repeated at 3 Hz (similar to that observed in typical absences of childhood absence epilepsy) in strict relation with myoclonias recorded on EMG. These seizures occur many times a day. Associated seizures are present in 2/3 of the cases, the most frequent association being GTCS in 45%. The age at onset is about 7 years. There is a male preponderance. The evolution is variable and seems to depend on the existence or not of GTCS. Classical cotherapy with valproate and ethosuximide with appropriate plasma levels is more efficient if myoclonic absences are non-associated with GTCS. In cases where GTCS are associated, there is often an unfavourable outcome, with persistence of myoclonic absences or with modification of the epilepsy with a possible evolution towards a generalized cryptogenic or symptomatic form.