Genetic testing among patients evaluated for epilepsy surgery

Genetic testing performed to identify the underlying etiology of epilepsy has become increasingly common and is now being recommended as part of the presurgical evaluation for epilepsy surgery. This study aimed to characterize the types of genetic tests performed in patients evaluated for epilepsy surgery and assess how genetic findings have influenced clinical treatment decisions and outcomes during the last decade in a tertiary epilepsy center.

Pediatric and adult epilepsy patients treated at the tertiary Kuopio Epilepsy Center in Finland are given the opportunity to participate in an EpiBiomarker study, which aims to identify epilepsy-related biomarkers and has established a comprehensive prospective database encompassing detailed clinical information including data of the possible preoperative evaluation and genetic testing results.

We identified 448 patients who (or their guardian) had provided consent to the Epi Biomarker study out of the 563 patients who had been evaluated for epilepsy surgery between January 1, 2015, and December 31, 2024. Altogether 117/448 patients (26.1%) had undergone some form of genetic testing before or during their presurgical evaluation. Clinical preoperative genetic testing became increasingly common in the later years of the study, ranging from 6.1% of patients evaluated in 2016 to 40.5% in 2024. Genetic etiology was identified in 8.0% of patients (36/448) and the identified genetic etiologies increased from 1.1% (2015) to 13.5% (2024). Only 4/36 (11.1%) of these genetically diagnosed patients underwent resective epilepsy surgery and only two of these patients were completely seizure-free at 1-year post-operative follow-up.

Germline genetic testing is increasingly incorporated into the presurgical evaluation of patients with epilepsy, leading to a higher detection of underlying genetic etiologies. Improved recognition of these etiologies may enhance clinical decision-making by providing additional context for treatment planning and prognostic assessment, while also helping to reduce unnecessary investigations in selected cases.