Abstracts

Juvenile myoclonic epilepsy (JME) is an idiopathic generalized epileptic syndrome. It is often considered as benign because of its non-lesional nature and favourable clinical long-term prognosis. The characteristic EEG pattern is presented with bilateral symmetric polyspike-wave complexes with anterior accentuation. Focal EEG abnormalities are not exclusive in patients with an unequivocal diagnosis of JME. A Group of 39 patients of both sexes (17 male, 22 female), aged from 12 to 26 years (mean 17.8 years) with JME were studied for focal EEG abnormalities recorded during the clinical follow-up. Mean seizure onset was 13.5 years. Diagnosis was made according to the history and EEG records. Antiepileptic treatment was started with valproate. Initial clinical and EEG assesment was carried-out after the generalized tonic-clonic seizure (mainly induced by sleep-deprivation), in 51% of JME patients. Absences in 21% and myoclonic jerks in 28% of patients were observed as initial epileptic events and reffered for EEG examinations. Complete, stable, long-term seizure control was achieved with valproate use in 87% of patients. In remaining 13% no favorable therapeutic response of AEDs was noted, mainly due to the irregular lifestyle. Repeated EEGs during sleep and when awake showed the interictal polyspike-wave pattern or fast/classical spike-wave discharges. Generalized EEG patterns were prevalent as expected: polyspike-waves or spike-wave discharges non-related to photic stimulation were noted in 66.7% and paroxysmal abnormalities to photic stimulation in 35.9%. Non-specific abnormalities were shown in 10.3%, while, bilateral anterior spikes and sharp waves were recorded in 23.1% of JME adolescents. Localization-related EEG abnormalities (focal slow waves shifting between the hemispheres, spikes, sharp waves and focal onset or asymmetrical generalized discharges) were noted in 23,1% of our JME patients. In more than one fourth of our JME patients, EEG showed focal abnormalities in addition to the generalized EEG patterns. These features should not be mislead to the erroneous interperetation of EEG characteristic for localization-related epilepsy.