Early myoclonic encephalopathy, early infantile epileptic encephalopathy, and benign and severe infantile myoclonic epilepsies: a critical review and personal contributions.

Nosological confusion within the epilepsies with myoclonic manifestations occurring in early life has led several epileptologists to separate more rigorously true myoclonic seizures from pseudomyoclonic ones and to identify clusters of homogeneous parameters that may lead to the formulation of syndromatic groupings. In recent years, four neonatal, infantile, and early myoclonic syndromes have been proposed: early myoclonic encephalopathy (EME), early infantile epileptic encephalopathy (EIEE), benign infantile myoclonic epilepsy (BIME), and severe infantile myoclonic epilepsy (SIME). These are reviewed critically, historically, and in the context of personal observations. The author's conclusions are that there is some justification to support, provisionally, a nosological place for the EME syndrome, that a nosologically separate position for the EIEE syndrome appears less firm, and that it seems safer to consider it at this time as an early variant of the West syndrome. From personal observations it appears that BIME and SIME, while justifiably constituting recognizable entities, may best be combined into a single syndrome of "infantile myoclonic epilepsy following febrile convulsions," with variable clinical outcomes.