# Two-year outcomes following modified transsylvian peri-insular hemispherotomy

## TL;DR

A modified surgical technique for treating drug-resistant epilepsy in children leads to high seizure freedom and low complications over two years.

## Contribution

A modified transsylvian peri-insular hemispherotomy technique achieves excellent long-term seizure outcomes with minimal complications.

## Key findings

- All 32 patients were seizure-free at 12 and 24 months post-surgery.
- 71% of patients were weaned off anti-seizure medications by 24 months.
- Only 3% of patients experienced complications requiring additional treatment.

## Abstract

Hemispherotomy is an effective treatment for well-selected patients with drug-resistant hemispheric epilepsy. Successful hemispherotomy leading to seizure cessation has been associated with improved neurodevelopmental outcomes and reduced healthcare utilization. This study reports seizure outcomes and complications in a large, consecutive, single-surgeon series of pediatric hemispherotomy cases using a surgical approach with modifications to previously-reported techniques.

All patients undergoing transsylvian peri-insular hemispherotomy for drug-resistant hemispheric epilepsy between May 2017 and April 2021 by a single surgeon were prospectively enrolled in an epilepsy surgery registry. With retrospective review of medical records, data were collected on baseline characteristics (demographics, epilepsy history, anti-seizure medications, neurodevelopmental status, EEG features, and imaging characteristics), operative complications, hospital course, and seizure outcomes (Engel scale at 12- and 24-month follow-up).

All 32 consecutive patients (aged 15 months–19 years) were seizure-free (Engel Class 1) 12 and 24 months after hemispherotomy. At 12 months, 31 patients (97%) had Engel Class 1A outcomes, and 1 patient (3%) had an Engel Class 1D outcome. These results were maintained through 24-month follow-up. Among 31 patients taking anti-seizure medications before surgery, 22 (71%) were weaned off all agents by 24 months. One patient (3%) developed post-operative hydrocephalus requiring ventriculoperitoneal shunt placement.

In an etiologically heterogeneous cohort of patients undergoing hemispherotomy for drug-resistant epilepsy, a modified transsylvian peri-insular technique led to high rates of sustained seizure freedom with minimal complications.

The online version contains supplementary material available at 10.1007/s00381-025-06825-1.