Abstracts

Rationale: Surgical resection of epileptogenic foci may be restricted due to location, structural limitations, or presence of eloquent cortex. RNS has been shown to be an additional well-tolerated and safe alternative treatment in such resection-limited cases (Heck et al., 2014). Enatsu, et al. (2012) report a case of a patient with refractory bitemporal lobe epilepsy who received RNS therapy followed by right temporal lobectomy 2 years later. RNS therapy was restarted post op and the patient has since been clinically seizure free. Thus far, there is no literature for concurrent resection and RNS therapy. We present two patients who received simultaneous resection and RNS therapy for treatment of medically refractory partial onset epilepsy.  Methods: A retrospective case series review was performed, including medical records and electrocorticography (ECOG) data for two patients who received simultaneous surgical resection and RNS. An additional eight patients at our center with RNS therapy only were also reviewed. Seizure frequency at baseline and at 6 months post-op was compared between these two groups.  Results: Patient A is a 28yo man with refractory right temporal lobe epilepsy (TLE). Presurgical imaging revealed normal MRI brain, and FDG-PET showed decreased metabolic activity in the right temporal region. ECOG showed epileptogenic zone (EZ) to involve the right anterior temporal lobe with quick posterior spread. A non-dominant temporal lobectomy to the Vein of Labbe was performed and RNS was placed with 2 posterior temporal strips. He had >95% decline in seizure frequency at 6 months post op. Patient B is a 59yo woman with refractory left TLE. Presurgical imaging revealed hippocampal asymmetry (left smaller than right) on MRI brain and unremarkable FDG-PET. ECOG showed the EZ to include the majority of the left temporal lobe with quick spread to the subfrontal region. On bedside cortical mapping, eloquent cortex was present in the posterior EZ (tongue movement, speech arrest, hearing change). A sub-total left anterior temporal lobectomy was performed with placement of 3 RNS leads: 2 posterior temporal, 1 subfrontal (not connected). She has > 75% decline in seizure frequency at 6 months post op. There are a total of eight additional RNS patients with at least 6-month follow up at our center: Three left frontal lobe epilepsy, two left TLE, one left parietal lobe epilepsy, and two bitemporal lobe epilepsy. Notably, two patients had a resection years prior to RNS placement. Seizure reduction for this cohort at six months post-op ranges from 0-50%. This study is not powered for statistical significance.  Conclusions: We present two patients who received simultaneous resection and RNS therapy for medically refractory focal epilepsy with marked reduction in seizure frequency. RNS used in conjunction with resection could potentially help expedite the time to seizure reduction.ReferencesEnatsu, R, et al. Complementary effect of surgical resection and responsive brain stimulation in the treatment of bitemporal lobe epilepsy: A case report. Epilepsy & Behavior.2012;24(2012),513-516.Heck, C, et al. Two-year seizure reduction in adults with medically intractable partial onset epilepsy treated with responsive neurostimulation: Final results of the RNS System Pivotal trial. Epilepsia.2014 Mar;55(3):432-441.  Funding: No funding