Prospective study of seizures in the elderly in the Marshfield Epidemiologic Study Area (MESA)

Purpose: To assess the incidence, etiology, antiepileptic drug (AED) use, and quality of life in patients having their first seizure at age 50 years or older. Methods: All patients in the Marshfield Epidemiologic Study Area (MESA) aged 50 years or older having their first seizure between July 1, 1996, and June 30, 1998, were identified through the diagnostic coding system. Patients were followed up for 12 months for recurrent seizures. Etiologies, drug treatments, magnetic resonance imaging (MRI), computed tomography (CT), or EEG results and medication adverse effects were recorded. Those patients who reached 1-year follow-up received a quality of life (QOLIE-31) survey. Results: Forty-eight patients having a first seizure were identified (162 of 100,000). Twelve patients had had recurrent seizures, and 36 had a single seizure at the time of study entry. Fourteen of these 36 had had an abnormal MRI, CT, or EEG. The remaining 22 had a single seizure and normal imaging and EEG. Six of these had one or more subsequent seizures, and all six were in the group with normal tests. Etiologies included vascular, neoplasm, trauma, dementia, metabolic, and unknown. Seventy-five percent of the patients achieved seizure control with phenytoin, carbamazepine, and/or valproate. Twenty-seven percent experienced adverse side effects. None had been given second-generation AEDs as an initial treatment. Thirty-one patients received the QOLIE-31 survey; 20 did not complete the survey for various reasons. The mean QOLIE-31 scores for those completing the survey were significantly higher than those of the reference cohort. Conclusions: The incidence of first seizure in MESA is high in the elderly and increases with advancing age. As in other studies, vascular causes accounted for the largest etiology. Use of new AEDs was uncommon. There was a high incidence of untoward side effects related to the traditional AEDs. High morbidity and mortality unrelated to seizures limits follow-up analysis in the elderly. Quality-of-life analysis via QOLIE questionnaires is problematic in this population.