Ictal EEG Patterns in Temporal Lobe Epilepsy: Associations with Pathology and Long-Term Surgical Outcome

Objective: To evaluate ictal-electroencephalography (EEG) patterns in lesional temporal lobe epilepsy (TLE) and its association with pathology, long-term postsurgery seizure freedom, and time to first seizure. Methods: We retrospectively analyzed 4,169 seizures in 702 patients with drug-resistant TLE with postsurgery follow-up ranging from 2 to 20 years (mean 52 months). Ictal-EEG patterns and Ebersole classification were correlated with pathology and long-term remission and resolution of epilepsy. Multivariable logistic regression and Cox models identified independent predictors of outcome and recurrence. Results: At latest follow-up, 77.4% patients were seizure-free of which 18% achieved resolution of epilepsy. Seizure freedom was highest with tumoral (88%), vascular (84%), and hippocampal sclerosis (79%) pathologies, whereas focal cortical dysplasia (FCD) showed persistent seizures. Rhythmic theta activity at ictal-EEG onset was associated with hippocampal sclerosis, whereas faster and irregular rhythms and disorganized patterns (Ebersole type 3) were more frequent in FCD ( p < 0.001). Ictal theta at onset was associated with seizure freedom ( p < 0.002), while alpha–beta activity ( p = 0.032) and repetitive spikes ( p = 0.035) predicted recurrence. Concordance of semiology, ictal, and inter-EEG with magnetic resonance imaging (MRI) predicted seizure freedom, while discordance strongly predicted poor outcome (12.5% vs. 3.8%, p < 0.001). On multivariable analysis, EEG-MRI discordance (odds ratio [OR] 3.67), acute postoperative seizures (APOS) (OR 1.88), and Ebersole type 3 patterns (OR 3.03) independently predicted persistent seizures (hazard ratio ∼2–2.5), while pathology did not influence the outcome. On Kaplan–Meier analysis of time to first seizure recurrence, patients with FCD, Ebersole type 3 pattern, and ictal EEG–MRI discordance showed earlier recurrence whereas hippocampal sclerosis showed longer seizure-free survival. Conclusion: Ictal EEG–MRI discordance, APOS, and disorganized ictal patterns independently predicted earlier seizure recurrence, whereas hippocampal sclerosis conferred a protective effect. Together with electroclinical concordance, these findings position ictal EEG as a functional marker of network organization and a key determinant of long-term outcome in TLE. Publication History Article published online: 15 July 2026 © 2026. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. (https://creativecommons.org/licenses/by/4.0/) Thieme Medical and Scientific Publishers Private Limited A-13A, Graphix Tower 1, 6th floor, Sector 62, Noida 201309, Uttar Pradesh, India