EPILEPSY WITH ELECTRICAL STATUS EPILEPTICUS DURING SLOW SLEEP AND SECONDARY BILATERAL SYNCHRONY

In 3 children with ''epilepsy with electrical status epilepticus durin g slow sleep'' (ESES), we estimated interhemispheric small time differ ences (TDs) during spike-wave activity in EEG by coherence and phase a nalysis by the two-dimensional autoregressive model to differentiate t heir continuous diffuse spike-waves during slow-wave sleep (CSWS) betw een primary bilateral synchrony and secondary bilateral synchrony (SBS ). Maximal TDs at onset of apparently bilateral synchronous spike-wave bursts (BSSWs) during slow-wave sleep were 12.0-26.5 ms (mean 20.3 ms ) with consistent leading hemispheres in eight bursts of the 3 patient s, indicating SBS as pathophysiology of their CSWS. This suggestion wa s supported by their clinico-EEG findings, including the effect of a s ingle oral dose of clobazam (CLB) on EEG. Three ictal BSSWs of atypica l absence seizures in 2 patients were also analyzed to obtain maximal TDs of 17.9-41.7 ms (mean 26.3 ms) at onset, with the same leading sid es as in sleep, also indicating SBS. Examination of intraburst TD vari ations showed no consistent disappearance of TDs during the latter par t of the bursts, in either sleep or the ictal EEGs of atypical absence s, and a role of the corpus callosum was suggested in the generation o f SBS in ESES.