Abstract
Detailed clinical and electroencephalographic long-term follow-up studies were made on 14 cases (3 boys and 11 girls) of severe myoclonic epilepsy in infancy (SME).
1) Familial predisposition to convulsions was observed in as many as 9 cases (64.3%).
2) Onset of convulsive seizures or characteristic partial seizures ranged from two to seven months of age, and additionally atypical absences and myoclonic seizures appeared at ages between seven months to 4 years 5 months
3) Alternating hemiconvulsions and/or generalized convulsions were observed in 14 cases (100.0%), characteristic partial seizures with ocular deviation and cyanosis in 11 cases (78.6%), atypical absences in 13 cases (92.2%) and myoclonic seizures in 10 cases (71.4%). Convulsive seizures were characterized by being easily precipitated by fever and hot baths, and often occuring in a cluster or status epilepticus.
These seizures were very intractable; at the time of follow-up convulsive seizures were not suppressed in any case and atypical absences and myoclonic seizures were suppressed at between 4 years to 17 years in only 5 cases.
4) Despite almost normal development prior to the onset of seizures, all the cases showed overt slowing in mental development after one year of age.
5) EEG back ground activity deteriorated with age, although mild in infancy.
6) Epileptic discharges were hardly detectable in infancy, while after age one all the cases showed epiletipc discharges characterized by the combination of diffuse(100.0%) and focal (92.9%) epileptic discharges.
7) Photosensitivity and pattern-sensitivity were observed in as many as 7 cases (50.0%) and 5 cases(37.7%), respectively, and clinical seizures were activated by light or geometric patterns in 5 cases (71.4%) of those with photosensitivity and all 5 cases with pattern-sensitivity.
From these findings, SME was suggested to be a specific type of secondarygeneralized epilepsy with characteristic clinical course and remarkably poor prognosis.
