The Effective Use of Laser Ablation to Treat Mesial Temporal Lobe Epilepsy in the Setting of Implanted Responsive Neurostimulation

BACKGROUND: Up to 16% of patients with responsive neurostimulation (RNS) implants for bilateral temporal epilepsy are found to have seizures originating mainly from just 1 lobe. OBJECTIVE: To describe the first use of laser interstitial thermal therapy (LITT) in a patient with a bilateral RNS implant to ablate the predominant temporal lobe and help control seizures. METHODS: A 55-year-old woman treated for temporal lobe epilepsy with conflicting information regarding lateralization underwent RNS implantation. She was then discovered to have seizures with electrographic onset nearly all from the right amygdala and hippocampus. She was offered LITT to ablate the affected region in the right temporal lobe, followed by reimplantation of the RNS lead in the remnant of the right hippocampal tail. RESULTS: Despite the positioning of the RNS ferrule on the operative side and the depth electrode in the contralateral lobe, we observed no significant artifact and obtained stable LITT temperature mapping using magnetic resonance. Laser ablation and RNS device replacement proceeded without complications. The patient has remained seizure-free for 6 months since the ablation in the setting of weaning antiseizure medications and regaining ambulation. CONCLUSION: LITT ablation can safely and effectively be performed in a patient with a concurrent RNS implant. Maintenance of the RNS device after ablation allows for continual detection and management of seizures.