ABSTRACT
Background: Responsive neurostimulation (RNS) is an implantable device for persons with medically refractory focal-onset epilepsy. We report a single-center experience for RNS outcomes with special focus on stereoelectroencephalography (sEEG) for seizure onset localization. Methods: We performed retrospective review of patients with drug resistant focal epilepsy implanted with the RNS System for a minimum of six months between July 2014 and July 2019. Records were reviewed for demographic data, epilepsy duration, seizure frequency, number of prior antiepileptic drugs (AEDs), number of AEDs at RNS System implantation, prior epilepsy surgery or device use, previous seizure localization with sEEG, and RNS system information. Clinical response was defined as a 50% reduction in seizures. Differing response rates were calculated using Fisher Exact test. Results: 30 patients met inclusion criteria. Seventeen (57%) underwent previous sEEG. Average clinical follow up was 3.0 years. Overall response rate was 70%. Median seizure reduction was 74.5%. Response rate was 82.3% for patients with sEEG compared to 53.8% without (p = 0.08); 37.5% for prior epilepsy surgery compared to 81.8% without (p = 0.02); 70% for mesial temporal onset; 50% for previous vagal nerve stimulator compared to 77.3% without (p = 0.13). Conclusion: Our response rates match or surpass outcome metrics of previous studies. Although limited by small study size, subpopulation analyses show positive response rates in patients with previous sEEG versus no sEEG and in temporal versus extratemporal pathology. Additional research is needed to evaluate efficacy of RNS in patients with previous epilepsy surgery, and utility of sEEG in this population.
ABSTRACT
BACKGROUND: Patients with bitemporal lobe epilepsy are generally not considered for surgical resection. Fortunately, responsive neurostimulation provides another avenue for the management of this challenging disease process. In conjunction with our epileptologist, we consider responsive neurostimulation for patients who have clinical features of temporal lobe epilepsy without clear localization on imaging and stereoelectroencephalography. METHODS: Here we describe our technique for implanting a responsive neurostimulator (NeuroPace, NeuroPace Inc., Mountain View, California) with depth electrodes monitoring the hippocampus and parahippocampus using stereotactic robotic guidance (ROSA, Medtech SA, Montpeillier, France). RESULTS: We have used this technique with 5 patients without morbidity. Four of 5 patients have received clinical benefit (Engel classification I-III). Promisingly, long-term seizure monitoring with use of the NeuroPace system has suggested lateralizing information on 3 of these patients that was not apparent on previous invasive monitoring. CONCLUSIONS: Robotically implanted responsive neurostimulation is a safe and effective treatment for bitemporal epilepsy and can possibly lead to valuable diagnostic information to guide future surgical management in patients who previously were not considered candidates for resective or ablative surgery.
