Abstracts

Seizures in Juvenile Myoclonic Epilepsy (JME) are dependent on the sleep-wake cycle and precipitant factors, among which sleep deprivation is one of the most important. Still an underdiagnosed syndrome, misinterpretation of the EEGs has been reported to contribute to diagnostic delay in one to two thirds of misdiagnosed cases. Despite this, a proper quantitative EEG investigation of sleep deprivation effects has not been performed. The aim of this study was to investigate the effect of sleep deprivation on EEGs in a series of 41 JME patients who had not yet had syndromic diagnosis. 41 patients, 16-50 yr. (mean 25.4) who had not had the diagnosis of JME after a delay of 8.2 yr. (12 days to 24yrs), had 2 EEG recordings separated by a 48-hour interval without any changes in their medication. The exams were always taken at 7 a.m. preceded by a period of 6 hours of sleep (called routine EEG) and after sleep deprivation (sleep-deprived EEG). The same protocol was followed in both exams and included a rest wakefulness recording, photic stimulation, hyperventilation for 5 minutes and a post-hyperventilation period. Sleep was not necessarily recorded. The EEGs were analyzed as to the effect of sleep deprivation on the number, duration, morphology, localization and predominance of epileptiform abnormalities in the different stages. The paroxysms were counted in isolation as well as in bursts, independent of their duration. The discharge index per minute in all different phases was calculated. Statistical analysis was done with the t-test and the McNemar test. Out of the 41 patients, 4 presented normal EEG recordings on both occasions. In 37 (90.2%) there were some epileptiform discharges (ED). The number of patients with ED ascended from 26 (70.3%) in the routine EEG to 32 (86.5%) in the sleep-deprived exam. The presence of generalized spike-wave (considered the most commonly seen pattern in JME) and multispike-wave (considered the most specific) increased from 20 (54.1%) and 13 (35.1%) in the first EEG to 29 (78.4%) and 19 (51.4%) in the second, respectively (McNemar test p[lt]0.005 and p[lt] 0.01). As to localization, the number of generalized, bilateral and synchronous discharges with frontocentral predominance increased from 21 (56.8%) to 30 (81.1%) (p[lt]0.01). The discharge index also increased; while 8 patients (21.6%) presented greater rate in the routine EEG, 25 (67.6%) did so in the sleep-deprived EEG; this was seen mainly during somnolence and sleep (p[lt]0.001). Moreover, the paroxysms were also longer in the sleep-deprived EEG. Sleep-deprived EEG is a powerful tool in JME and can significantly contribute to the syndromic characterization of this syndrome. (Supported by FAPESP (Funda[ccedil][atilde]o de Amparo a Pesquisa do Estado de S[atilde]o Paulo), CAPES (Coordena[ccedil][atilde]o de Aperfei[ccedil]oamento de Pessoal de N[iacute]vel Superior).)