High frequency oscillations relate to cognitive improvement after epilepsy surgery in children

Abstract Objective To investigate how high frequency oscillations (HFOs; ripples 80-250Hz, fast ripples(FRs) 250-500Hz) and spikes in intra-operative electrocorticography(ioECoG) relate to cognitive outcome after epilepsy surgery in children. Methods We retrospectively included 20 children who were seizure free after epilepsy surgery using ioECoG and determined their intelligence quotients(IQ) pre- and two years postoperatively. We analyzed whether the number of HFOs and spikes in pre- and postresection ioECoGs, and their change in the non-resected areas relate to cognitive improvement (with ≥5 IQ points increase considered to be clinically relevant (=IQ+ group) and Results The IQ+ group showed significantly more FRs in the resected tissue (p=0.01) and less FRs in the postresection ioECoG (p=0.045) compared to the IQ- group. Postresection decrease of ripples on spikes was correlated with postoperative cognitive improvement (correlation coefficient = −0.62 with p=0.01). Conclusions Postoperative cognitive improvement was related to reduction of pathological HFOs signified by removing FR generating areas with subsequently less residual FRs, and decrease of ripples on spikes in the resection edge of the non-resected area. Significance HFOs recorded in ioECoG could play a role as biomarkers in the prediction and understanding of cognitive outcome after epilepsy surgery.