Prevalence and incidence of epilepsy in Tokyo.

All children 3 years of age on January 1, 1975 in the Fuchu area of Tokyo were neurologically examined for 6 years (number examined: 17,044). The cumulative incidence of epilepsy (i.e., recurrent nonfebrile seizures) was 4.3/1,000 and that of occurrence of a single nonfebrile seizure (NS) was 4.7/1,000. Febrile convulsions (FCs) were observed in 82/1,000 in this population. The population was followed for 6-11 years after the first examination. During the follow-up (a) 4 of 80 children who had a single NS before age 3 years developed recurrence after age 3 years; (b) development of epilepsy was found in three of 1,323 randomly (10%) selected healthy children for comparison (2.3/1,000); (c) among 1,406 children with FCs, epilepsy developed in 24 (17/1,000) and a single NS occurred in 28 (20/1,000); and (d) the total cumulative incidence of epilepsy was 8.2/1,000 in the population aged 9-14 years. Age-specific annual incidence of epilepsy was highest in the age range 0-1 year (1.9/1,000), gradually falling with advancing age. The point prevalence for active epilepsy (having had a seizure within the past 5 years) was 2.8/1,000; that for inactive epilepsy was 5.4/1,000 (total 8.2/1,000). Epilepsy developed by age 14 years in (a) one-half of children with NS, (b) approximately 2% children with FCs, (c) 0.2% of healthy children with no seizure before age 3 years, and (d) an estimated 2% of potential epileptic carriers (having spike EEG abnormality by age 3; 15% of the population) who had not had a seizure by age 3 years.