Neurophysiological effects of continuous cortical stimulation in epilepsy – Spike and spontaneous ECoG activity

Abstract Objective The effect of continuous subthreshold cortical stimulation (CSCS) over the seizure onset zone (SOZ) in epilepsy was analyzed to delineate the affected physiological processes. Method ECoG data was recorded over SOZ and adjacent regions in patients (n = 7) with refractory-epilepsy. Data was reviewed before and during 2 Hz cortical electrical stimulation. Group differences were estimated using ANOVA and correlation with Pearson’s r. Results CSCS reduced background ECoG power at SOZ (p  Conclusion This study shows changes in cortical electrophysiology during CSCS over the SOZ where spike rate reduction correlated with two independent electrophysiological parameters, background power and coherence. These results suggest the possibility of a causal relationship between spectral power, coherence and interictal spikes which may be related to seizure rate. Significance Improved understanding of the effect of electrical stimulation on epileptic tissue could suggest improvements in stimulation paradigms to reduce seizure frequency.