Effect of sleep deprivation on spike-wave discharges in idiopathic generalised epilepsy:: a 4x24 h continuous long term EEG monitoring study

The aim of the study was to investigate the effect of sleep and sleep deprivation on spike-wave discharges (SWD) in an idiopathic generalised epileptic patient population by continuous long term cassette EEG monitoring for 4 x 24 h. In ten patients with idiopathic generalised epilepsy, showing SWD during awake state and in sleep as well, EEG and sleep polygraphy was recorded for 4 x 24 h. Sleep was deprived during the second 24 h. Awake state, NREM1, NREM2, NREM3+4 and REM sleep duration and number of SWD episodes were evaluated in 4 min intervals by visual scoring. For analysing the effect of 'day' and 'night', 'vigilance' and 'sleep deprivation' (SD) on the density variables multi-way ANOVAs were carried out in different designs. SWD densities for different vigilance states were not significantly different during 'day' and 'night' in 24 h without SD or rebound after SD. Sleep had an activating effect SWD densities being the highest during NREM1 and NREM2. There was an increase of SWD densities in all vigilance states after SD, but SWD densities remained the highest in NREM1 and NREM2. Our results support the view that sleep dependent rather than sleep independent mechanisms cause activation of SWD after SD in generalised epilepsy. We assume that fine graded vigilance fluctuations, that are more frequent after SD, have an essential role in SWD activation in superficial sleep or even in wakefulness. (C) 2002 Elsevier Science B.V. All rights reserved.