Prognostic value of scalp EEG ictal patterns in epilepsy surgery of hippocampal sclerosis

Temporal lobe epilepsy associated with hippocampal sclerosis (TLE-HS) is a surgically treatable epileptic syndrome. While the core of pre-surgical evaluations rely on video-EEG, recent studies question the necessity of recorded seizures denying a possible role of ictal EEG in surgical decision. This study aims to retrospectively assess the prognostic value of EEG ictal patterns in TLE-HS, in order to identify which patients need further investigations before offering surgery. We included TLE-HS patients who underwent surgery with at least one captured seizure during non-invasive pre-surgical video-EEG recordings. They were classified in “mesial” and “lateral/mixed”, according to the ictal EEG patterns, defined by the frequency of the discharge (mesial ≥ 5 Hz, lateral < 5 Hz). Seizure outcome was assessed by Engel’s Class. Statistical analyses were performed to evaluate associations between EEG patterns and post-surgical outcomes. Sixty-nine exhibited a mesial pattern, forty- two displayed lateral/mixed patterns. Mesial pattern group had a significantly higher rate of postsurgical seizure freedom (82.7