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Updated: Jun 12, 2026
Anteromesial Temporal Lobectomy for Medically Intractable Temporal Lobe Epilepsy: An Operative Study
Published on: August 15, 2025
Design considerations for a multicenter randomized controlled trial of early surgery for mesial temporal lobe
Jerome Engel1, Michael P McDermott, Samuel Wiebe
1Department of Neurology, UCLA, Los Angeles, California 90095-1769, USA. engel@ucla.edu
Purpose:
To describe the trial design for the multicenter Early Randomized Surgical Epilepsy Trial (ERSET). Patients with pharmacoresistant epilepsy are generally referred for surgical treatment an average of two decades after onset of seizures, often too late to avoid irreversible disability. ERSET was designed to assess the safety and efficacy of early surgical intervention compared to continued pharmacotherapy.
Methods:
ERSET is a randomized controlled, parallel group clinical trial with blinded outcome adjudication. Participants are patients with mesial temporal lobe epilepsy (MTLE) older than the age of 12 who have had pharmacoresistant seizures for not >2 years and are determined by detailed evaluation to be surgical candidates prior to randomization. The primary outcome measure is seizure freedom in the second year of a 2-year follow-up period. Health-related quality of life (HRQOL), neurocognitive function, ancillary outcomes, and adverse events were also measured.
Results:
Significant methodologic problems addressed by the study design included the following: recruitment of participants early in the course of epilepsy; establishment of operational definitions for "pharmacoresistant" and "early"; and standardization of diagnostic testing, medical treatment, and surgical interventions across multiple centers.
Discussion:
Rigorous trial designs to assess surgical interventions in epilepsy are necessary to provide evidence to guide treatment. This article is the first of a series; trial results will be reported in subsequent publications.
Insights
The Early Randomized Surgical Epilepsy Trial (ERSET) evaluates early epilepsy surgery versus medication. This trial aims to determine if prompt surgical intervention improves outcomes for patients with drug-resistant epilepsy.
Area of Science:
- Neurology
- Clinical Trials
- Epilepsy Surgery
Background:
- Pharmacoresistant epilepsy patients often face irreversible disability due to delayed surgical referral.
- Surgical intervention for epilepsy is typically considered two decades after seizure onset.
Purpose of the Study:
- To describe the design of the Early Randomized Surgical Epilepsy Trial (ERSET).
- To assess the safety and efficacy of early surgical intervention compared to continued pharmacotherapy for epilepsy.
Main Methods:
- A randomized controlled, parallel group clinical trial with blinded outcome adjudication.
- Inclusion criteria: patients aged >12 with mesial temporal lobe epilepsy (MTLE), pharmacoresistant seizures for ≤2 years, and confirmed surgical candidacy.
- Primary outcome: seizure freedom in the second year of a 2-year follow-up; secondary outcomes include HRQOL, neurocognition, and adverse events.
Main Results:
- The study design addressed methodological challenges in early epilepsy treatment research.
- Key challenges included early participant recruitment, defining "pharmacoresistant" and "early" intervention, and standardizing multi-center protocols.
Conclusions:
- Rigorous trial designs are essential for evaluating surgical interventions in epilepsy.
- The ERSET trial provides a framework for generating evidence to guide epilepsy treatment decisions.
