Incidence of first epileptic seizures in the canton of Geneva, Switzerland.

Abstract

We wished to determine the incidence of first provoked and nonprovoked epileptic seizures in the canton of Geneva, Switzerland. Between June 1, 1990 and May 31, 1991, we collected all cases of suspected epileptic seizures referred to the two hospitals of the county of Geneva, Switzerland and to the private neurologists of the town. The diagnosis probability was based on clinical data from the patient chart and the EEG data. The classification of risk factors proposed by the International League Against Epilepsy (ILAE) Commission on Epidemiology and Prognosis was used. In all, 273 cases were collected. The age-adjusted incidence rate (U.S. population as standard) is 69.4 in 100,000. We observed a bimodal distribution of the cases with age (71 in the group aged 0-10 years and 107.5 in those aged > 60 years). Ninety-seven cases were classified as having provoked seizures (incidence: 25.2 in 100,000). Alcohol consumption (29.8%) and cerebrovascular diseases were the most frequent causes (16.4%). One hundred seventy-six cases were classified as having unprovoked seizures (incidence: 45.6 in 100,000) with the following distribution: seizures in relation with a stable cerebral condition, 69 cases (incidence: 17.9); seizures in relation with an evolutive cerebral condition, 27 cases (incidence: 7); and seizures of unknown etiology, 80 cases (incidence: 20.8). The incidence rate of first epileptic seizures in the canton of Geneva is quite similar to that reported in a French study (Epilepsia (1990;31:391-394) in which the same methodology for case ascertainment was used. Our data clearly demonstrate that the classification of risk factors proposed by the ILAE Commission on Epidemiology and Prognosis is useful and particularly easy to use in epidemiological surveys.