Abstracts

Juvenile myoclonic epilepsy (JME) is a frequent form of idiopathic generalized epilepsy. The EEG is characterized by generalized epileptiform activity (EA) such as polyspike and slow waves complexes (PS/SW), irregular spike and slow waves complexes (S/SW) and rapid S/SW (faster than 3Hz). Focal abnormalities as well as asymmetric generalized bursts have been reported and may cause difficulties in diagnosis.
We analyzed retrospectively 1484 files from adult epilepsy out-patient unit of the Neurology Department of University of Sao Paulo Clinics Hospital from the period from January 2001 trough December 2002 in order to identify patients with JME. All patients were evaluated by medical residents and epileptologists and were selected based on the following criteria: normal neurological examination; onset in adolescence of myoclonic seizures associated or not to other seizure types. All patients were taking AED and have been followed before that period in the same out-patient unit. We reviewed 127 EEG from these 35 patients.
The EEG findings from 35 patients (19 female, 16 male) with JME aged between 12-44 years were analyzed. The number of EEG/patient ranged from 1 to 13 (mean 3.6). Fifteen EEG were performed during wakefulness, 111 during wakefulness, drowsiness and sleep, and one tracing only in sleep. Twenty-one exams were done during arousal. All patients had normal background activity. Eight patients (22.9%) had persistent normal EEG and 19 (54.2%) had at least one normal EEG during the follow-up. Twenty seven patients (77.1%) had abnormal EEG. The abnormalities consisted of isolated generalized EA in 22 (81.1%), focal and generalized EA in 3 (11.1%) and intermittent diffuse slowing in 2 (7.4%). The generalized EA present in 25 out of 35 patients (71.4%) had a unique morphology in 13 (52%) and in 12 (48%) different patterns were observed. The generalized paroxysms consisted of: a) irregular S/SW in 19 (76%), asymmetric in 7 (28%); b) PS/SW in 12 (48%), asymmetric in 2 (8%); c) rapid S/SW in 5 (20%), asymmetric in 3 (12%); d) finally spikes, sharp waves and irregular slow waves in 6 (24%), asymmetric in 1 (4%). Focal paroxysms were observed in 3 patients (8.6%), always associated to generalized EA and photosensitivity occurred in 6 (17.1%).
The knowledge of some atypical EEG aspects in JME, such as normal tracings and eventual asymmetric generalized and focal discharges, is of great importance in the early recognition of this syndrome, which will lead to a correct treatment and accurate prognosis.