Prognosis of juvenile myoclonic epilepsy 45 years after onset

Objectives: Juvenile myoclonic epilepsy (JME) is the most common idiopathic generalized epilepsy subsyndrome, contributing to approximately 3% to 11% of adolescent and adult cases of epilepsy. However, little is known about the long-term medical evolution of this clinical entity. The aim of this study was to analyze long-term outcome in a clinically well-defined series of patients with JME for seizure evolution and predictors of seizure outcome. Methods: In this retrospective cohort study, we analyzed seizure outcome in 66 patients who had JME, were treated at the Department of Neurology, Charite-Universitatsmedizin Berlin, and were initially diagnosed by a single senior epileptologist. Results: After a mean follow-up time of 44.6 years (20-69 years), 59.1% of patients remained free of seizures for at least 5 years before the last contact. Among the seizure-free patients, 28 (71.8%) were still taking antiepileptic drugs and 11 (28.2%) were off medication for at least the last 5 years. We identified manifestation of additional absence seizures at onset of JME as an independent predictor of an unfavorable outcome regarding seizure freedom. Conclusions: A significant proportion of patients with JME were seizure-free and off antiepileptic drug therapy in the later course of their disorder. Patients with JME and additional absence seizures might represent a different JME subtype with a worse outcome.