Abstracts

Rationale: Epileptic activity of childhood absence epilepsy (CAE) is characterized by bursts of 3-Hz generalized spike-wave discharges (GSW), which are widely considered to be symmetric and synchronous. Synchronous oscillation produced in thalamo-cortical neuronal network and abnormal cortical hypersynchronization has been hypothesized. The purpose of this study was to investigate oscillation activity by studying the topography and spectral power of these discharges and better understanding pathologic dynamics. Methods: We studied 14 patients diagnosed with CAE (M:F=5:9, mean age: 8.3 years old). Ten second epochs of sustained 3-Hz GSW epileptic and baseline segments showing alpha rhythm (48 epileptic and 35 baseline segment, each 10- seconds segment) were analyzed by Fast Fourier transformation using EEGLAB Toolbox for MATLAB. We compared the topography and power spectrum (0-20Hz band) to epileptic and baseline segments Results: Spectral power in epileptic epochs showed multiple rhythmic 6-7 spectral peaks (multiples of 2.5-3Hz). The first peak in epileptic epochs was observed at 2.5-3Hz with maximum of the power spectrum and subsequent peaks showed gradually decremental power. Topographic map of epileptic epochs showed greatest power in diffuse frontocentral area at -3Hz and more localized frontopolar area at subsequent multiple peaks. However, baseline epochs showed maximum power at 9-10Hz only at localized occipital area and no other spectral peak. Conclusions: Characteristic epileptic hallmark of CAE (3-Hz GSW) was typical and consistent but not the sole feature in our spectral EEG analysis. We found additional rhythmic oscillatory peak power in epileptic discharges. These findings suggest that excitability in thalamocortical networks with multiple hypersynchronization and dynamic mechanism of absence epilepsy.