Abstracts

Rationale: Continuous spike and waves during sleep (CSWS) is an EEG pattern activated during slow wave sleep. CSWS was originally defined as a spike and wave index > 85% during slow wave sleep. Three epileptic syndromes are related to CSWS, Landau-Kleffner syndrome (LKS), epileptic encephalopathy with CSWS (ECSWS) and atypical benign partial epilepsy (ABPE). High-dose diazepam (HDDZP) therapy has been reported to reduce CSWS on EEG. Frequent epileptiform discharges during sleep may result not only in seizures, but also cognitive, motor and psychosocial dysfunction. We analyzed number of spikes and amplitude of 1) spikes and 2) slow waves separately on EEG before and after HDDZP to elucidate the efficacy of HDDZP in children with CSWS. Methods: We retrospectively reviewed medical charts and overnight video EEG (VEEG) of 9 patients (age, 3 to 15 years old) who had diffuse/focal CSWS and underwent HDDZP. The 9 patients consisted of 5 LKS, 3 ECSWS and 1 ABPE. Overnight VEEGs were performed at three time points; before HDDZP, on the night of HDDZP and at 6 month follow-up. Analysis at all time points included: spike count during 10 minutes of N2 and N3 sleep, amplitude measurement of up to 50 representative 1) spikes and 2) slow waves during N2 and N3 sleep.Results: Seven out of nine patients had reduction of spike number on the night of HDDZP. The total number of spikes reduced from a mean of 961 (311-1527) before HDDZP to 660 (115-1186) on the night of HDDZP in nine patients. The number of spikes reduced from a mean of 433 (74-734) to 218 (52-479) in N2 and from a mean of 528 (237-862) to 442 (38-1118) in N3. Amplitude of 1) spikes and 2) slow waves became lower on the night of HDDZP in all patients. The amplitude of spikes in N2 decreased 10-89% (57%). The amplitude of slow waves in N2 decreased 10-81% (50%). The amplitude of spikes in N3 decreased 10-86% (62%). The amplitude of slow waves in N3 decreased 51-91% (58%). Follow-up VEEG was performed within 6 months of HDDZP in 7 patients. The number of spikes further declined in 4 patients. The amplitude of spikes and slow waves declined in 3 patients in N2. The amplitude of spikes and slow waves declined in 4 patients in N3.Conclusions: HDDZP produces a reduction in the number and amplitude of epileptiform discharges in children with CSWS. Reduction in spike number is more prominent in N2 than N3 sleep. Reduction in spike and slow wave amplitude was observed in both N2 and N3 stage. Remission can be reached following an initial partial response to HDDZP. The clinical relevance of these findings has yet to be determined.