Long-term neuropsychological follow-up and nosological considerations in five patients with continuous spikes and waves during slow sleep.

Continuous spikes and waves during slow sleep (CSWSS) is a well-known EEG pattern that can be associated with cognitive and behavioural deterioration. We present the long-term neuropsychological follow-up and nosological considerations of five patients who developed CSWSS during childhood. All five of our patients presented CSWSS, although the duration and severity of this pattern varied. The outcome was of three basic types: acquired frontal dementia, language deficits and normal. Four of our patients were initially diagnosed with Landau-Kleffner syndrome but have had markedly diverse outcomes in terms of the severity and type of compromise. Our data suggest that the initial diagnosis, according to current nosological categories, has almost no prognostic significance, while the length and the age of onset of CSWSS, the site of epileptiform activity and the individual neuropsychological profile are more useful for identifying the long-term outcome of patients with CSWSS.