Linguistic and pragmatic skills (comprehension that is context dependent) were examined in 10 right-handed children and adolescents with the continuous spike-waves during slow sleep syndrome (CSWSS) and compared to that of a control population of 36 children, in a study at CHRU de Tours and Universite Francois Rabelais, Tours, France. Patients with CSWSS had lower scores in tests measuring lexical and pragmatic skills compared to controls, whereas oral comprehension was unaffected. Language impairment showed no improvement when patients were in remission and even after total disappearance of EEG anomalies. The language impairment profile of CSWSS is different from that of Landau-Kleffner syndrome, characterized by auditory and verbal agnosia with limited spoken language and loss of verbal comprehension. Evaluation of language skills and long-term outcome are important in the management of epileptic syndromes. 
COMMENT. Continuous spike-waves during slow sleep syndrome (CSWSS) is a childhood epilepsy characterized by EEG spike waves during at least 85% of slow sleep, and clinically, by neuropsychological and behavioral disorders. CSWSS and Landau-Kleffner syndrome are similar in age of onset, mild epilepsy, and severe neuropsychological disorders. The present study shows that both syndromes are associated with impairments in language development, but the acquired dysphasias have different profiles. It is postulated that the nature and severity of the neuropsychological and language deficits are determined by the site of paroxysmal activity during early cerebral and language development.