Abstracts

Rationale: Palliative resections can be offered when a seizure focus resides in, or near, eloquent cortex and it is not possible or desired to resect all of the seizure focus. The RNS® System (NeuroPace, Inc.) offers an added option of using brain-responsive neurostimulation to treat the remaining, unresectable portion of the seizure focus. Methods: The RNS System was implanted in 3 patients concurrently with a resection up to the margins of eloquent cortex. In all 3 cases, cortical strip leads were placed at the margins of the resection. Results: Patient 1 had a partial resection of the right parietal focal cortical dysplasia (FCD) concurrent with the placement of the RNS System with two right parietal cortical strip leads over sensory cortex. The patient’s baseline seizure report was 6 seizures per month. The first electrographic seizure was recorded by the RNS System 1 month post-op. The patient had a series of electrographic seizures recorded until stimulation was enabled at 0.5 mA (5 months post-op), at which point electrographic and clinical seizures discontinued. The electrographic seizures returned (17 months post-op) with a more robust onset pattern than previously observed, and the overall count of electrographic abnormalities treated with stimulation increased from < 100 per day to approximately 2000 per day. At the last follow-up visit the patient maintains clinical seizure freedom.Patient 2 had a minimal 2 cm frontal partial resection concurrent with the placement of the RNS System with two left frontal cortical strip leads over motor cortex. The patient’s baseline seizure report was 75 seizures per month. The patient had 8 seizures recorded by the RNS System in the first 9 days post-op. Brain-responsive neurostimulation was enabled 14 days post-op at 1 mA. The patient has been clinically and electrographically seizure free for 15 months. As of the last follow-up visit, the patient continues to receive approximately 100 stimulations per day for electrographic abnormalities and remains clinically seizure free.Patient 3 had a left parietal partial resection up to the margin of the motor cortex concurrent with placement of the RNS System with one cortical strip lead over motor cortex and one depth lead in the motor cortex. The patient’s baseline seizure report was 90-150 nocturnal seizures per month and “several” during the daytime each day. The patient had clinical and electrographic seizures immediately following surgery that were recorded by the RNS System. Brain-responsive neurostimulation was enabled 7 days post-op at 0.5 mA and was titrated up to 3.0 mA over 1.4 years. At last follow-up visit, the patient reported less frequent and less severe seizures and that their seizures are now exclusively nocturnal.There were no surgical or post-surgical complications in any of these cases. Conclusions: The RNS System can be placed concurrently with a resection in patients that can only have a partial resection of their seizure focus. In a small retrospective series of patients with a resection combined with RNS System treatment, two patients became seizure free and a third patient reported less frequent (62.5% reduction) and less severe seizures. Funding: None