The Epileptic Encephalopathy with Continuous Spike and Waves During Slow-Wave Sleep

Abstract

Epileptic encephalopathy with continuous spike and waves during slow-wave sleep (CSWS) is a spectrum of epileptic conditions best defined by the association of cognitive or behavioral impairment acquired during childhood and not related to another factor than the presence of abundant interictal epileptiform discharges (IEDs) during sleep, which tend to diffuse over the whole scalp. It is part of the childhood focal epileptic syndromes. Some cases are genetic, related to GRIN2A mutation that impairs the glutamate NMDA receptor functions, and overlap with benign epilepsy with central temporal spikes. Others are related to a structural brain lesion that may affect either the cortex or the thalami. Most cases are of unknown etiology. Landau-Kleffner syndrome (LKS) is a particular presentation where acquired aphasia is the core symptom. Clinical, neurophysiological, and cerebral glucose metabolism data support the hypothesis that IEDs play a prominent role in the cognitive deficits by interfering with the neuronal networks at the site of the epileptic foci but also at distant connected areas. Therefore, the treatment should aim to suppress CSWS. This may be achieved using conventional antiepileptic drugs, but corticosteroids seem to have more pronounced and sustained efficacy. Outcome for epilepsy is usually good, CSWS being an age-dependent EEG pattern, whereas outcome for cognition, language, and behavior is variable. Rehabilitation represents an important part of the treatment, and visual forms of language should be encouraged in children with LKS.