Bilateral oscillations for lateralized spikes in benign rolandic epilepsy

Abstract

Purposes To elucidate the oscillatory dynamics with respect to interictal spike occurrence in benign rolandic epilepsy (BRE). Methods Using a whole-scalp magnetoencephalography (MEG), we recorded scalp EEG and MEG signals in 10 BRE patients (age 8–12 years) and visually identified unilateral interictal spikes that were simultaneously present on both EEG and MEG channels. We obtained the peak timing of individual spike complex based on MEG single-dipole modeling, and then applied wavelet transform to analyze the time–frequency components of corresponding MEG signals with respect to spike occurrence. Results In the hemisphere with time-domain spike waveforms, we identified a clear increase of 0.5–40 Hz activity around the spike peak, most prominent at alpha band (8–13 Hz). Notably, at the approximate timing we also observed an increase in 0.5–25 Hz oscillations over the homotopic area in the other hemisphere where no spike signals were found. Conclusions Our results indicate bilateral increases in 0.5–25 Hz oscillations during unilateral spike formation in BRE patients. By using wavelet transform analysis, one could be able to detect some irritative feature that would in visual analysis remain undetected.