Haemodynamic changes associated with epileptic activity were investigated at Christian-Albrechts-University, Kiel, Germany, using simultaneous acquisitions of EEG and functional MRI in 12 children with symptomatic and cryptogenic continuous spikes and waves during slow sleep (CSWSS). MR findings were compared to electric source analysis, and all patients showed spike-related positive (activations) and negative (deactivations) blood oxygenation-level-dependent changes (P<0.05). The activations involved bilateral perisylvian region and cingulated gyrus in all cases, bilateral frontal cortex in 5, bilateral parietal cortex in 1, and thalamus in 5 cases. Electrical source analysis demonstrated a similar involvement of perisylvian regions, independent of the area of spike generation. Spike-related deactivations were found in precuneus, parietal cortex and medial frontal cortex in all patients and in caudate nucleus in 4. Independent of the cause, CSWSS cases were characterized by activation of a similar neuronal network: perisylvian region, insula and cingulate gyrus. The activations correspond to both initiation and propagation pathways. 
COMMENT. CSWSS (or electrical status epilepticus during sleep) is an age related (peak at 4-5 yrs old) epileptic encephalopathy characterized by interictal epileptic discharges during >85% non-REM sleep, and receptive language, cognitive, and behavioral disorders. Seizures occur during sleep or while awake, partial, generalized tonic-clonic or myoclonic. CSWSS is distinguished from Landau-Kleffner syndrome by the continuous bilateral and diffuse spike-wave activity, persisting through all slow sleep stages. (Browne, Holmes 2004) Four children with epilepsy and CSWSS, followed between 18 mos and 4 years of age, showed a pattern of behavioral and cognitive disturbances similar to that of autistic spectrum disorder.