Hemispherotomy for atypical teratoid rhabdoid tumor-associated drug-resistant epilepsy: illustrative case.

backgroundDrug-resistant epilepsy (DRE) following treatment for atypical teratoid rhabdoid tumor (ATRT) is rare. The authors report a case in which hemispherotomy was performed to palliate new-onset DRE after ATRT therapy. OBSERVATIONS: A 6-year-old boy with a large left thalamic ATRT underwent subtotal resection, chemotherapy, and radiation therapy. His neurological baseline remained stable, with right hemiparesis, right hemifield neglect, and apraxia of speech. Two years after tumor recurrence and treatment, he developed frequent tonic seizures of left hemispheric origin. Despite trials of multiple antiseizure medications, the seizures persisted. Evaluation revealed left hemispheric seizure onset and hypometabolism. Given his existing deficits and unilateral disease, the potential benefits of hemispherotomy were determined to outweigh the risks. The patient underwent a left peri-insular hemispherotomy and has remained seizure free off medication without worsened neurological function. LESSONS: In carefully selected patients with aggressive tumor, unilateral seizure onset and preexisting deficits, hemispherotomy can be a well-tolerated and effective treatment for DRE, even in nontraditional contexts such as ATRT. This case highlights the importance of weighing surgical risks against functional baseline when considering epilepsy surgery in pediatric tumor cases. https://thejns.org/doi/10.3171/CASE24728.