Multiple subpial transections with concomitant responsive neurostimulation of the insula: illustrative case.

backgroundFocal epilepsy arising from the eloquent cortex can be treated with palliative surgical interventions such as multiple subpial transection (MST) or responsive neurostimulation (RNS). These techniques can be performed to reduce the burden of disabling seizures while avoiding disability associated with resection of the eloquent brain. OBSERVATIONS: A 17-year-old girl with a history of complex, refractory multifocal epilepsy and previous right anterior temporal lobectomy and left temporal neocortical RNS presented with refractory status epilepticus. Scalp electroencephalography showed seizures that began prior to RNS detection, suggesting a focus outside of the left anterior temporal lobe. MRI showed new edema throughout the left insula. MST and concurrent insular RNS lead placement were performed. The patient was discharged 2 weeks later, and at the 6-month follow-up, she had a 100-fold reduction in clinical seizures and RNS detections. LESSONS: This technical report is the first description of 1) concurrent MST and RNS, and 2) placement of a paddle electrode for the RNS over the surface of the insula using a transsylvian approach. Surgery in this case provided both immediate and sustained reduction in disabling seizures over several months. https://thejns.org/doi/10.3171/CASE24445.