Spike wave discharges

State of Vigilance and SWDs

The states of vigilance, such as wakefulness, slow wave sleep or REM sleep, highly influence the occurrence of discharges. In more than 80% of cases spike-wave discharges appear during passive wakefulness or during instable vigilance periods. Rarely, spike-wave discharges occur during deep slow wave sleep, active wakefulness or REM sleep. The prevalence for spike-wave discharges to occur at drowsiness and light slow-wave sleep closely corresponds to the occurrence of seizures in humans. This indicates that spike-wave discharges can easily breakthrough at transitions between sleeping and waking. Also sleep spindles preferably occur in these periods.

Properties of SWDs

The spike-wave discharges are bilaterally symmetrical and generalised over the cortex. As is the case in human absence epilepsy, minor changes in behaviour can be seen during the presence of a spike-wave discharge. Facial myoclonic jerks, twitching of the vibrissae, accelerated breathing, head tilting and eye twitching accompany the EEG signs. Otherwise the animals are immobile.