Acquired epileptic frontal syndrome as long-term outcome in two children with CSWS

Continuous spikes and waves during slow sleep (CSWS) are a well-known EEG pattern that can be associated with cognitive and behavioural deterioration. We present the long-term clinical, neuropsychological and EEG follow-up of two patients who developed CSWS during childhood. In both the CSWS onset was followed immediately by rapid cognitive and behavioural deterioration. Later the CSWS fragmented or fluctuated and the spike-wave discharges diminished and this was associated with progressive clinical improvement. At the same time bilateral frontal EEG abnormalities appeared awake and in sleep. After the initial period of rapid cognitive and linguistic improvement both patients stabilised. The latest neuropsychological assessment showed a frontal syndrome. The presence of frontal EEG abnormalities superimposed on CSWS, their persistence after CSWS resolution and, in addition, the finding of subtle frontal-type neuropsychological alterations early in recovery may indicate poor long-term outcome.