Prevalence of epilepsy in Okayama Prefecture: a neuroepidemiologic study.

On the prevalence day, 2,378 epileptic children were identified. Therefore, the prevalence rate for epilepsy was 8.2 per 1,000. The lowest prevalence rate was 1.2 in children under one year of age, and the highest was 11.0 at five years of age. The rate was higher for males than females. The annual incidence rate for epilepsy was estimated at 145.0 per 100,000 for 1975. The onset of seizures was high in the first three years, totaling 1,795 cases (77.7%), and this decreased after four years of age. Primary generalized epilepsy was found in 577 cases (31.7%), secondary generalized epilepsy in 167 (9.2%), partial epilepsy with elementary symptomatology in 205 (11.3%), with complex symptomatology in 61 (3.3%) and partial seizures secondarily generalized in 801 (44.5%). The study on such a number of cases had hitherto never been reported in the world.