Epilepsy and multiple sclerosis in Sicily: a population-based study

PURPOSE: To evaluate the association between epilepsy and multiple sclerosis (MS), we analyzed the incidence of epilepsy in a population-based incidence cohort of MS in Catania, Sicily. METHODS: According to Poser's diagnostic criteria, 170 incident cases of MS have been identified from 1975 to 1994 in the city of Catania. All these subjects underwent a complete neurological examination to confirm the diagnosis of MS and to identify those patients with a history of seizures. Diagnosis of epilepsy was based on the criteria proposed by the International League Against Epilepsy (ILAE) in 1993, and seizures were classified according to the classification of the ILAE, 1981. RESULTS: From 1975 to 1994, 170 subjects with MS had the clinical onset of the disease. The mean annual incidence of MS was 2.3/100,000 (95% CI, 2.0-2.6). Of the 170 defined MS patients, four developed epilepsy after the onset and also diagnosis of MS, giving an incidence rate of epilepsy of 285/100,000 person years at risk (95% CI, 119-684) and 147.8/100,000 when age adjusted to the world standard population. The cumulative risk of developing epilepsy after the onset of MS, evaluated by using the life-table methods, was zero at 1 year and 1.76% at 5 years. Of these four patients, three were classified as having partial seizures with secondary generalization and one with tonic-clonic seizures. CONCLUSIONS: Our data are consistent with those reported in literature suggesting that the risk of developing epilepsy is threefold higher among MS patients than in the general population.