Incidence of epileptic syndromes in Rochester, Minnesota: 1980-1984

Purpose: To determine the incidence and the distribution of epileptic syndr omes in a well-defined population. Methods: By using the records-linkage system of the Rochester Epidemiology Project, we screened all the residents of Rochester, Minnesota, who receive d a diagnosis of seizures, convulsions, or epilepsy from 1980 through 1984. One hundred fifty-seven residents with incident epilepsy (recurrent unprov oked seizures) were classified by using the International League Against Ep ilepsy (ILAE) Classification of the Epilepsies and Epileptic Syndromes. Res idents with special syndromes were excluded. With a pretested algorithm, pa tients were classified at three levels of specification: major syndromic gr oups (e.g., localization-related syndromes), syndromic subgroups (e.g., idi opathic epilepsy with age-related onset), and whenever possible, individual syndromes. Results: All but one patient were classified into major syndromic groups an d subgroups. The annual age-adjusted incidence per 100,000 population was 5 2.3 cases (34.9 for localization-related epilepsies; 7.7 for generalized ep ilepsies; 9.7 for undetermined epilepsies). Incidence was 0.2 for idiopathi c, 17.2 for cryptogenic, 17.5 for symptomatic localization-related epilepsi es, 3.7 for idiopathic, 1.7 for symptomatic or cryptogenic (age-related), a nd 2.3 for symptomatic (non age-related) generalized epilepsies. Conclusions: With the exception of idiopathic epilepsies, the incidence of the major syndromic categories in our study was higher than that provided b y previous population-based studies.