In JME patients, prolonged and short epileptiform discharges have an opposite relationship with the sleep-wake cycle

Background and aims We recently demonstrated that the recording of epileptiform discharges (EDs) longer than 2,68 s with prolonged EEG, in Juvenile Myoclonic patients predict motor seizure recurrence. The aim of this study is to verify whether the longer and shorter EDs have a different distribution in relation to the sleep-wake cycle. Methods We further analyzed the 32 EEG recordings of our work, studying the temporal distribution of EDs longer and shorter than 2.68 s. By applying a mixed-effects Poisson regression model (subject = random factor), we tested whether the frequency of longer or shorter EDs: 1) depends on the “time of day” parameter 2), is greater in wakefulness or sleep, 3) is maximum upon awakening or at the sleep onset. Results EDs longer than 2.68 s, but not shorter ones, peak at 7 AM (p = 0.022). Regarding the sleep-wake cycle, longer EDs are more frequent in wakefulness (p < 0.001), shorter ones in sleep (p < 0.001); the frequency of EDs longer than 2.68 s is maximum in the hour following morning or afternoon awakening (p < 0.001), when the occurrence of short epileptiform discharges is significantly less likely (p < 0.001), when compared to the others hours of the day. Conclusions Prolonged EDs, which predict seizure recurrence, have a circadian distribution and a dependence on the sleep-wake cycle opposite to the shorter ones. Their peak after awakenings reflects the characteristic temporal distribution of seizures in Juvenile Myoclonic Epilepsy. This simple observation may guide future studies aimed at resolving the intricate relationship between epileptiform discharge and seizures.