A Clinical and Electroencephalographic Study of Myoclonic Epilepsies in Infancy and Early Childhood

Part 1. On the Classification

Abstract

Clinical and electroencephalographic features of myoclonic seizures (MS) were studied in 149 patients. On the basis of early development history, age at onset of epilepsy, combination of tonic spasm (TS), and an existence of generalized bilateral synchronous slow spike and wave burst (GSSW) or multifocal spikes (MFS) in interictal EEG, the patients could be placed into 5 groups:
Group A (60 cases): Normal prior development to onset of epilepsy, absence of TS, GSSW and MFS. This group showed a high incidence of either febrile convulsions or epilepsy in the family history (FH), and MS being predominant seizure type. Prognosis for seizure control and mental outcome ranged from fair to good. Group B (18 cases): Normal prior development, presence of TS, GSSW. Seizure and mental outcome was poor. Group C (13 cases): Normal prior development, absence of TS, GSSW, and the combination of MFS and the age of onset less than 1 year. This group also exhibited a high incidence of FH and multiple seizure types, easily precipitated by fever. Prognosis was very poor. Group D (17 cases): Delayed development with gross neurological abnormalities often associated cerebral palsy. Group E (29 cases): Delayed development before onset of seizures and history of West syndrome without gross neurological abnormalities in all patients. The remaining 12 patients could not be classified.