Seizure outcomes of temporal lobe epilepsy surgery in patients with normal MRI and without specific histopathology

Jugoslav Ivanovic,Bård K Krossnes,John Hald,Milo Stanisic,Are H Pripp,Ylva Østby,Pål G Larsson,Kristin Å Alfstad,Arild Egge,Jan G Fjeld

doi:10.1007/s00701-017-3127-y

Abstract

BackgroundSeizure outcome following surgery in pharmacoresistant temporal lobe epilepsy patients with normal magnetic resonance imaging and normal or non-specific histopathology is not sufficiently presented in the literature.MethodsIn a retrospective design, we reviewed data of 263 patients who had undergone temporal lobe epilepsy surgery and identified 26 (9.9%) who met the inclusion criteria. Seizure outcomes were determined at 2-year follow-up. Potential predictors of Engel class I (satisfactory outcome) were identified by logistic regression analyses.ResultsEngel class I outcome was achieved in 61.5% of patients, 50% being completely seizure free (Engel class IA outcome). The strongest predictors of satisfactory outcome were typical ictal seizure semiology (p = 0.048) and localised ictal discharges on scalp EEG (p = 0.036).ConclusionSurgery might be an effective treatment choice for the majority of these patients, although outcomes are less favourable than in patients with magnetic resonance imaging-defined lesional temporal lobe epilepsy. Typical ictal seizure semiology and localised ictal discharges on scalp EEG were predictors of Engel class I outcome.

Highlights

The role of surgery as a treatment of pharmacoresistant temporal lobe epilepsy (TLE) is well established [12, 28, 39]
Unsatisfactory seizure outcome was achieved in 38.5% (10/26) of patients, 40% (8/20) in the anteromedial temporal lobectomy (AMTL) and 33.4% (2/6) in the anterolateral temporal lobe (ALTL) subgroups
AMTL performed on the language-dominant side resulted in satisfactory seizure outcome in 56% (5/9) and on the language-non-dominant side in 64% (7/11) of the patients

Summary

Introduction

The role of surgery as a treatment of pharmacoresistant temporal lobe epilepsy (TLE) is well established [12, 28, 39]. Between 70 and 90% of patients with hippocampus sclerosis (HS) on MRI concordant with other localisation methods may achieve seizure control following TLE surgery [17, 19, 30–32, 35, 40]. Unlike in patients with HS, the rate of seizure freedom following TLE surgery in this subgroup is lower and varies from 20 to 80% [2, 3, 5, 8, 21, 24, 34, 37]. There is no widely adopted standardised investigation protocol for TLE patients with N-MRI, and presurgical assessment remains challenging. Seizure outcome following surgery in pharmacoresistant temporal lobe epilepsy patients with normal magnetic resonance imaging and normal or non-specific histopathology is not sufficiently presented in the literature

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