UC Irvine

OBJECTIVE: This study investigates the network differences in pre-surgical resting-state EEG between individuals with unilateral temporal lobe epilepsy who become seizure-free and those who continue to have seizures after epilepsy surgery. METHODS: We retrospectively identified 15 individuals with unilateral TLE who were seizure-free (SF) after epilepsy surgery and 13 who continued to have seizures post-surgery (nSF). Functional connectivity was measured using cross-correlation techniques on clips of resting-state scalp EEG that were free of any visually apparent epileptiform abnormalities. RESULTS: Stronger pre-surgical functional connectivity was associated with favorable post-surgical outcomes. The SF group demonstrated significantly higher connectivity strength, particularly in cross-hemispheric and intra-hemispheric networks involving the ictal hemisphere (P = 0.02). Functional connectivity strength predicted post-surgical seizure freedom with 75 % accuracy (AUC = 0.77). Notably, individuals with the strongest connectivity were all seizure-free, despite heterogeneity in clinical characteristics or imaging findings. Connectivity strength did not correlate with age, disease duration, hippocampal sclerosis, or bilateral epileptiform abnormalities. CONCLUSION: Functional connectivity networks derived from visually normal EEG can provide non-invasive, non-redundant information beyond traditional assessments to predict post-surgical outcomes. SIGNIFICANCE: This study further supports the concept that epilepsy is a disorder of neural networks.