Defining benchmark outcomes for mesial temporal lobe epilepsy surgery: A global multicenter analysis of 1119 cases

Abstract Objective Benchmarking has been proposed to reflect surgical quality and represents the highest standard reference values for desirable results. We sought to determine benchmark outcomes in patients after surgery for drug‐resistant mesial temporal lobe epilepsy (MTLE). Methods This retrospective multicenter study included patients who underwent MTLE surgery at 19 expert centers on five continents. Benchmarks were defined for 15 endpoints covering surgery and epilepsy outcome at discharge, 1 year after surgery, and the last available follow‐up. Patients were risk‐stratified by applying outcome‐relevant comorbidities, and benchmarks were calculated for low‐risk (“benchmark”) cases. Respective measures were derived from the median value at each center, and the 75th percentile was considered the benchmark cutoff. Results A total of 1119 patients with a mean age (range) of 36.7 (1–74) years and a male‐to‐female ratio of 1:1.1 were included. Most patients (59.2%) underwent anterior temporal lobe resection with amygdalohippocampectomy. The overall rate of complications or neurological deficits was 14.4%, with no in‐hospital death. After risk stratification, 377 (33.7%) benchmark cases of 1119 patients were identified, representing 13.6%–72.9% of cases per center and leaving 742 patients in the high‐risk cohort. Benchmark cutoffs for any complication, clinically apparent stroke, and reoperation rate at discharge were ≤24.6%, ≤.5%, and ≤3.9%, respectively. A favorable seizure outcome (defined as International League Against Epilepsy class I and II) was reached in 83.6% at 1 year and 79.0% at the last follow‐up in benchmark cases, leading to benchmark cutoffs of ≥75.2% (1‐year follow‐up) and ≥69.5% (mean follow‐up of 39.0 months). Significance This study presents internationally applicable benchmark outcomes for the efficacy and safety of MTLE surgery. It may allow for comparison between centers, patient registries, and novel surgical and interventional techniques.