Sleep and epilepsy

Abstract

This review considers the effect of sleep on seizures and interictal electroencephalogram (EEG) paroxysmal activities (PAs), as classified by the International League Against Epilepsy criteria. No type of seizure is, per se, specifically linked with non-rapid eye movement (NREM) or rapid eye movement (REM) sleep. However, in some syndromes, seizures are more frequent in slow wave sleep (SWS) [partial motor or generalized seizure in benign epilepsy with centro-temporal spikes (BECTS), frontal seizures in idiopathic familial or not familial frontal lobe epilepsy and generalized tonic seizure in secondary generalized epilepsy are increased by SWS]. Conversely myoclonia and grand mal seizures are associated with awakening in some forms of generalized idiopathic epilepsy. There is a mean increase in PAs during SWS in generalized and in partial epilepsies on the whole. However, precise analysis shows that in partial cryptogenic or symptomatic epilepsy and, most likely, in the majority of generalized idiopathic epileptic syndromes about 20% of patients have an increase in PA density during SWS, 20% experience an increase in waking, 50% have very few PAs and in 10% there is no significant difference between sleep and waking. BECTS, however, exhibits a definite increase in sleep PA increase and in juvenile myoclonic epilepsy an increase in PAs during the intra-night awakening is reported. There are at least three syndromes, which cause a huge increase in PAs during sleep: the Landau-Kleffner syndrome and the syndromes of continuous focal or generalized spike-waves during SWS. Their physiopathology and neuropsychological consequences are discussed. Neurophysiological animal data are also reported highlighting the relationships between slow sleep oscillations and the generation of spike waves. A biochemical review is also presented.