Modulation of sleep interictal epileptiform discharges in partial epilepsyof childhood

Objective: NREM sleep increases the Interictal Epileptic Discharges (IEDs) in the majority of children affected by partial epilepsy (both symptomatic or cryptogenetic). Experimental data revealed that the normal sleep oscilla tions, leading to the appearance of spindles and delta waves on the surface EEG during NREM sleep, might develop into paroxysmal synchronization. Spec tral analysis enables the quantitative description of the dynamics of delta (slow wave activity, SWA, 0,5-4,5 Hz) and sigma activity (SA, 12.0-16.0 Hz ) and can be used to assess the relationship between SA, SWA and IEDs durin g sleep. Design and methods: We have performed overnight continuous EEG-polysomnogra phic studies in 7 patients (mean age 7.2 +/- 1.3). The temporal series of S WA and SA were obtained from a spike-free derivation lead. The IEDs count w as performed on the most active lead. Relationships between sigma and SWA a nd time series of IEDs were tested by means of correlation techniques after data normalization. Results: Our results revealed a significant higher correlation between IEDs and SA with respect to SWA in all the subjects, in total sleep time. The s ame analysis limited to NREM sleep highlights the better correlation betwee n SA and IEDs. Conclusions: Our data suggest that the neural mechanisms involved in the ge neration of sleep spindles facilitate the IEDs production in childhood part ial epilepsies at least in those strongly activated by sleep. (C) 1999 Else vier Science Ireland Ltd. All rights reserved.