The network integration of epileptic activity in relation to surgical outcome

Abstract Objective Epilepsy is a network disease with epileptic activity and cognitive impairment involving large-scale brain networks. A complex network is involved in the seizure and in the interictal epileptiform discharges (IEDs). Directed connectivity analysis, describing the information transfer between brain regions, and graph analysis are applied to high-density EEG to characterise networks. Methods We analysed 19 patients with focal epilepsy who had high-density EEG containing IED and underwent surgery. We estimated cortical activity during IED using electric source analysis in 72 atlas-based cortical regions of the individual brain MRI. We applied directed connectivity analysis (information Partial Directed Coherence) and graph analysis on these sources and compared patients with good vs poor post-operative outcome at global, hemispheric and lobar level. Results We found lower network integration reflected by global, hemispheric, lobar efficiency during the IED (p Conclusions Abnormal network patterns in epilepsy are related to seizure outcome after surgery. Significance Our finding may help understand networks related to a more “isolated” epileptic activity, limiting the extent of the epileptic network in patients with subsequent good post-operative outcome.