Retrospective study of febrile seizures: subsequent electroencephalogram findings, unprovoked seizures and epilepsy in adolescents.

A retrospective questionnaire to determine the prevalence of febrile seizures was given to adolescents (16- and 17-year-olds) in the final 2 years of secondary school at the five schools in Alexandroupolis, Greece. Parents were interviewed, and clinical and electroencephalographic examinations were performed in all adolescents with a history of febrile seizures. Of 1708 adolescents, 56 (3.3%) had experienced at least one febrile seizure. Of these, 44 (78.6%) were simple and 12 (21.4%) were complex febrile seizures. Recurrent seizures occurred in 22 cases (39.3%), and the mean age at onset was 25.1 months. There was a positive first-degree family history in eight cases (14.3%) and this increased to 27.3% in cases with recurrent seizures. Two of the adolescents (3.6%) had had one unprovoked seizure before the age of 3 years, and another two children developed epilepsy. Epileptiform electroencephalogram discharges were observed in only one case (1.8%) with generalized tonic-clonic epilepsy.