Abstracts

Rationale: The responsive neurostimulation (RNS) system offers the primary therapy of electrical stimulation by detecting electrocorticographic (ECoG) epileptiform activity and providing stimulation of epileptogenic foci. The RNS system also provides a longitudinal data array that guides many aspects of the clinical management of epilepsy. The RNS system has been found to have diagnostic and therapeutic implications beyond the benefit of stimulation alone. The purpose of this study is to demonstrate the different clinical implications of the RNS system data: confirm diagnosis, provide counseling regarding lifestyle modification, determine pharmacological management, and examine non-pharmacological alternatives. Methods: Four patients were selected for case study that represent the clinical management benefits of the RNS system's capability to provide longitudinal ambulatory ECoG data. Results: Confirm Diagnosis: A 34 year old male with left hemispheric epilepsy was implanted with the RNS system using left posterior parietal and posterior insula electrodes. One year after RNS implantation the patient reported experiencing a significant increase in seizure activity and change in seizure semiology. A review of the patient's ECoG data suggested that the majority of reported seizures were non-epileptic. This was later confirmed by ambulatory electroencephalogram (EEG) and video-EEG. The patient was subsequently referred for conversion disorder treatment and his non-epileptic seizures improved dramatically. Lifestyle Modification: 34-year-old female with a history of bitemporal lobe epilepsy was implanted with the RNS system targeting the right amygdala and hippocampus. She had a history of 1-2 episodes of status epilepticus each year. Review of historical ECoG data showed a significant increase in epileptiform activity on weekends. It was discovered that the patient was consuming increased amounts of caffeinated soda on weekends. The patient was asked to abstain from consuming caffeine on weekends and complied with the recommendation. The patient has experienced a statistically significant (p < 0.05) reduction in ECoG epileptiform activity on weekends and has not experienced any further episodes of status epilepticus to date over the subsequent year. Pharmacological Management: A 28 year old male with a history of bitemporal lobe epilepsy underwent a left temporal lobe resection followed by implantation of the RNS system targeting the right mesial temporal region. Using the RNS system as a seizure counter, we were able to quantify the effects of various treatment modalities on the patient's seizure frequency. The patient was started on Clobazam 3 years post-RNS system implantation and his reported seizure frequency dramatically decreased 2 months following the initiation of the medication. This was confirmed by RNS data which showed evidence of a significant decrease in ECoG epileptiform activity. Nonpharmacological Management: A 45 year old male with diagnostic findings of bitemporal lobe epilepsy underwent implantation of the RNS system using bimesial temporal electrodes. Review of historical ECoG data revealed that the vast majority of seizures appeared to be arising from the right temporal lobe. The patient subsequently underwent a right temporal lobectomy and became seizure free. Conclusions: The RNS system has proven to be an effective treatment option for patients with medically refractory epilepsy. These case studies suggest that the RNS system can also be used as an effective tool to guide the clinical management of epilepsy Funding: No funding was received in support of this abstract.