Landau-Kleffner syndrome: sleep EEG characteristics at onset

Objectives: Landau-Kleffner syndrome (LKS) and benign epilepsy with centro- temporal spikes (BECTS) are two forms of non-lesional age-related focal epi lepsies. LKS is a severe disease, affecting language abilities, attention a nd behavior, and evolving to acquired global aphasia. As LKS is usually rea dily responsive to an adequate pharmacological management, an early diagnos is of children at risk for this syndrome is essential. BECTS is characteriz ed by the absence of neurological or neuropsychological deficits throughout the course of epilepsy. However, children initially presenting some clinic al and EEG features suggesting BECTS may develop severe cognitive impairmen ts during the course of epilepsy. These cases raise the question of whether LKS and BECTS delineate fundamentally different conditions, or represent s ubclasses of a broad continuum. Methods: We compared sleep EEG characteristics of 7 children with typical L KS to those of 6 children with classical BECTS. Results: Morphology, topography, organization, and abundance of interictal abnormalities during sleep differentiated these two syndromes from epilepsy onset, before the occurrence of aphasic deficits in LKS. The specific slee p EEG patterns possibly predictive of LKS were (1) unilateral slow wave foc i, (2) bilateral independent spike-and-wave discharges, and (3) major activ ation of spike-and-wave discharges during sleep, exceeding 40% (40-90%) of the first sleep cycle and 30% (30-80%) of the following cycles. Conclusions: These data support the hypothesis that during LKS evolution, l anguage networks involved in the spread of abundant idiopathic interictal a bnormalities (and mainly slow waves) may be progressively inhibited and bec ome unable to carry out their normal physiological role. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.