Laser interstitial thermal therapy with a previously implanted responsive neurostimulation device: a multicenter experience. Illustrative cases.

BACKGROUND

Responsive neurostimulation (RNS) enables real-time electrographic monitoring and chronic assessment of seizure burden in two distinct brain regions. Laser interstitial thermal therapy (LITT) offers a minimally invasive treatment for mesial temporal epilepsy. Unilateral LITT that maintains functional RNS contralaterally poses significant challenges. As RNS use becomes more widespread, adjunctive seizure reduction therapies following implantation may become increasingly common. The authors present 2 cases illustrating a minimally invasive surgical approach.

OBSERVATIONS: Two patients with bitemporal RNS underwent long-term monitoring that revealed a significant unilateral predominance in seizure onset. LITT targeting the more active mesial temporal lobe while maintaining a functioning RNS contralaterally was recommended. Mesial temporal laser ablations were performed that accounted for existing RNS hardware and manufacturer-imposed MRI safety limitations. Both patients retained fully functional RNS systems postoperatively and experienced no complications. The laser ablations were technically successful with encouraging early seizure freedom outcomes. Long-term monitoring will determine sustained efficacy.

LESSONS: LITT was safely performed in the prone position in 2 patients with preexisting RNS systems. Caution is required to avoid hardware damage or electrode overheating during MRI. While further study is needed to assess outcomes, this technique offers a promising option for patients requiring targeted ablation following extended RNS monitoring. https://thejns.org/doi/10.3171/CASE25434.