Long-term seizure and functional outcomes following peri-insular hemispherotomy

To evaluate long-term seizure and functional outcomes after peri-insular hemispherotomy in a Middle Eastern cohort, identify predictors of seizure recurrence and describe the utility of the Wada test in patients with apparently generalized epileptiform discharges.

We retrospectively reviewed prospectively collected data for all patients who underwent a peri-insular hemispherotomy at the American University of Beirut Medical Center between 2012 and 2023. Clinical, radiologic, and electroencephalographic data were analyzed alongside long-term seizure and functional outcomes. Simplified Engel classification was used to categorize seizure outcomes. The modified Wada test was employed in select cases to clarify seizure lateralization and language dominance.

Fifteen patients (mean age at surgery 11.5 years) were included. Etiologies were acquired in 8, developmental in 5, and progressive in 2. The modified Wada testing in 6 patients confirmed unilateral onset in 4 with pseudo-generalized discharges, enabling surgery. At a mean follow-up of 70.5 months, 80% achieved Engel Class I outcomes. Seizure recurrence occurred in three patients, all with bilateral independent interictal discharges. Causes included incomplete disconnection and contralateral seizure onset. No relapse occurred beyond five seizure-free years. Functional outcomes were favorable with 69% retaining independent ambulation, and minimal behavioral or visual deficits.

Peri-insular hemispherotomy in this cohort yielded seizure freedom and functional outcomes comparable to international series. Late seizure recurrence underscores the need for extended postoperative surveillance. The modified Wada test effectively lateralized pseudo-generalized cases, expanding surgical eligibility and warranting further validation.