Significant Seizure Frequency Reduction in a Patient with Refractory Bitemporal Lobe Epilepsy Following the Transition from High-frequency to Low-frequency Stimulation Settings in RNS System Therapy
Abstract number :
3.177
Submission category :
18. Case Studies
Year :
2024
Submission ID :
478
Source :
www.aesnet.org
Presentation date :
12/9/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Stacey Kim, MEng, BA – Dignity Health Memorial Hospital - United Neuroscience Institute
Christel Benny, BS – United Neuroscience Institute
Sabrina Daug, BS – Dignity Health Memorial Hospital - United Neuroscience Institute
Brian Lee, MD, PhD, FAANS – Keck School of Medicine, University of Southern California
Charles Liu, MD, PhD – Keck School of Medicine, University of Southern California
Hari Prasad Veedu, MD, FACNS – Kern Medical
Rationale: The RNS System (NeuroPace) is playing an increasing role in managing medically intractable epilepsy in major tertiary centers. However, its relevance in underserved areas remain limited due to access disparities. While many patients implanted with RNS experience a significant reduction in seizures, poor responders to traditional high frequency stimulation (HFS) can experience a meaningful reduction in seizure frequency when switched to low frequency stimulation (LFS) [1]. We report a case with similar results at Kern Medical, a highly underserved public safety-net hospital with the only adult NAEC center (Level III) in the Central Valley of CA and affiliated with the USC Epilepsy Care Consortium.
Methods: A 64-year-old, right-handed male developed post-traumatic pharmacoresistant bitemporal epilepsy at age 39 years. Imaging showed bilateral mesial temporal sclerosis (left more prominent than right) and right orbitofrontal encephalomalacia. He has trialed various antiseizure medications and currently takes Cenobamate, Felbamate, Fycompa, and Brivaracetam. He underwent vagus nerve stimulator (VNS) implantation at the age of 48 years, followed by explantation 10 years later due to lack of efficacy. Finally, we implanted the patient with bilateral hippocampal RNS depth electrodes at the age of 60 years. We reviewed the patient's electronic medical record and RNS Patient Data Management System (PDMS) data. Stimulation frequency parameters for this case study were ≥100Hz (HFS) and < 20Hz (LFS) [2].
Results: Patient’s baseline median seizure frequency was 6.5 per month before RNS implantation. At traditional HFS settings applied for 30 months, the patient experienced a median seizure frequency of 4.5 seizures per month (31% reduction from baseline). The HFS parameters of 3.5mA, 200Hz, 0.2s therapies with a pulse width of 160μs and were programmed for the last 90 days before switching to LFS settings. The patient was then programmed at LFS of 2.5mA, 10Hz, 5s therapies with a pulse width of 160μs for 8 months at the time of review. With LFS, the patient experienced a median seizure frequency of one per month (85% reduction from baseline). HFS delivered 6.02 mins per day, compared to 113.77 mins per day with LFS.
Conclusions: Switching from HFS to LFS for our patient offered a substantial and meaningful reduction in seizure frequency. This case adds to the prior reported series of 10 patients, demonstrating that LFS could be an alternative approach for RNS patients poorly responsive to traditional HFS. Importantly, this report demonstrates that advanced RNS concepts can be relevant in highly underserved areas.
Funding: N/A
Case Studies