16. Electrical status epilepticus in «slow wave» sleep and Landau–Klefner syndrome

Abstract

Electrical status epilepticus in non-REM (without rapid eye-movements) sleep (ESES) and Landau–Kleffner syndrome (LKS) is rare epileptic encephalopathies occurring during childhood. ESES is defined by the EEG criterion, namely >85% time of non-REM sleep is occupied with bilateral continuous 1–3 Hz spike-waves (BCSWS). ESES is the only epileptic syndrome requiring the sleep EEG study to establish and follow-up the BCSWS. Main clinical syndromes related with the ESES/BCSWS are: atypical benign epilepsy with centro-temporal spikes (ABECTS), LKS, and opercular syndrome. LKS is characterized by verbal auditory agnosia as its typical aphasia, epileptiform EEG abnormalities and seizures. ESES occurs in 30–50% of patients. Clinical evolution of ESES is characterized by an active phase with BCSWS followed by the recovery phase when the patient is seizure-free but cognitive dysfunctions and behavioral disorders persist. The importance of early diagnosis and treatment initiation is stressed by clinical experience that neuropsychological sequelae cannot be resolved if a persistent active phase lasts for over 2 to 3 years. In our series of patients with ESES and LKS, EEG becomes normalized in both LKS and the ESES related to ABECTS, at latest during the puberty. However, some degree of cognitive or behavioral disorders is often persistent in adulthood.