# Long‐term predictors of seizure outcome after anterior temporal lobectomy in unilateral hippocampal sclerosis: A 281‐patient cohort with mean 10‐year follow‐up

## TL;DR

This study identifies long-term seizure outcome predictors after brain surgery for epilepsy, emphasizing the importance of detailed pre-surgical evaluation.

## Contribution

The study provides robust long-term predictors of seizure freedom after anterior temporal lobectomy in patients with hippocampal sclerosis.

## Key findings

- 62.6% of patients remained seizure-free at 10 years post-surgery.
- History of status epilepticus, ictal onset localization, and neuropsychological deficit lateralization were independent predictors of seizure freedom.
- Left ATL was associated with greater verbal memory decline, while quality of life improved significantly.

## Abstract

To identify long‐term predictors of seizure outcome after anterior temporal lobectomy (ATL) in a large, homogeneous cohort of patients with drug‐resistant temporal lobe epilepsy (TLE) and MRI‐defined unilateral hippocampal sclerosis (HS), all operated on by a single neurosurgeon with extended follow‐up.

We retrospectively analyzed 281 consecutive patients with unilateral HS who underwent standardized ATL performed by the same senior neurosurgeon. All patients had at least two years of follow‐up (mean 10.8 ± 5.79 years). Clinical history, neuropsychological evaluation, long‐term video‐EEG monitoring, and 1.5T MRI constituted the preoperative dataset. Twenty‐one variables were assessed as potential predictors of seizure outcome. Kaplan–Meier survival curves and univariate log‐rank tests identified candidate predictors; variables with p < .10 were entered into a multivariate Cox regression model. Cognitive and quality‐of‐life outcomes were evaluated using standardized neuropsychological batteries and the ESI‐55 questionnaire.

At 10 years postoperatively, 62.6% of patients remained seizure‐free (Engel I). Univariate analysis identified seven factors associated with seizure freedom, including history of focal‐to‐bilateral tonic–clonic seizures, history of status epilepticus, presence of psychogenic non‐epileptic seizures, IED predominance or exclusivity in the operated lobe, ictal onset exclusively in the operated lobe, and a preoperative neuropsychological deficit confined to the operated temporal lobe. Multivariate analysis revealed three independent predictors of seizure outcome: history of status epilepticus (HR = 2.11; p = .002), ictal onset confined to the operated temporal lobe (HR = .57; p = .018), and preoperative neuropsychological deficit restricted to the operated temporal lobe (HR = .59; p = .040). Cognitive outcomes were generally stable; left ATL was associated with greater verbal memory decline. Quality‐of‐life improved significantly at 2‐year follow‐up (p < .001), with better outcomes among seizure‐free patients.

In this large single‐surgeon cohort with one of the longest follow‐up durations reported, most patients with unilateral HS achieved durable seizure freedom after ATL. Status epilepticus, consistent ictal localization to the operated temporal lobe, and concordant preoperative neuropsychological deficit emerged as robust long‐term predictors. These findings reinforce the value of detailed presurgical evaluation—particularly ictal EEG concordance and neuropsychological lateralization—in optimizing surgical counseling, risk stratification, and patient selection.