Prognosis of juvenile myoclonic epilepsy is related to endophenotypes

PURPOSE To investigate if phenotypic variations have prognostic implications in juvenile myoclonic epilepsy (JME). METHODS Sixty-five consecutive JME patients had video-EEG recording and were followed for at least three years. Reflex traits were defined as seizures and/or EEG discharges induction by eye-closure, photic stimulation, language, praxis or calculation. Patients had psychiatric evaluation and answered to STAI (State-Trait Anxiety Inventory). Seizure control was classified according to Prasad et al. (2003).(24) Patients were divided into Group 1: good seizure control and Group 2: moderate or poor seizure control. Video-EEG/EEG evaluation was repeated in 21 patients. RESULTS Forty of 65 (61.5%) patients reached good seizure control, 25 (38.5%) of whom became seizure free. Group 2 patients had longer epilepsy duration (13.9±9.0 vs. 8.7±8.2; p=0.019); higher prevalence of the combination of all three seizure types (72.0% vs. 30.0%; p=0.003); discharges in baseline EEG (56.0% vs. 22.5%; p=0.008); seizure recording (68% vs. 20%; p<0.001) and sensitivity to praxis (63.6% vs. 29.6%; p=0.023). Compared to seizure-free patients, those with persistent seizures presented younger age at epilepsy onset (12.6±3.33 years vs. 15.4±5.47 years; p=0.015); higher prevalence of personality disorders (25% vs. 4%; p=0.029); higher scores in STAI-T (45.9±11.31 vs. 36.6±11.43; p=0.011) and higher incidence of sensitivity to praxis (58.6% vs. 25.0%; p=0.04) and to language (53.8 vs. 16.7%; p=0.026) tasks. Repetition of EEG/video-EEG revealed a parallel evolution of reflex traits disappearance and seizure control. DISCUSSION Clinical features and reflex traits have prognosis implications in JME.