Conversion/addition of RNS Leads to Thalamic Nuclei: Impact on Treatment Outcomes
Abstract number :
2.264
Submission category :
4. Clinical Epilepsy / 4C. Clinical Treatments
Year :
2024
Submission ID :
505
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Mohammad Taba, MD – University of California, Los Angeles
Aria Fallah, MD, MS – UCLA Mattel Children's Hospital
Hiroki Nariai, MD, PhD, MS – UCLA Mattel Children's Hospital
Dawn Eliashiv, MD – UCLA
Rationale: In cases of drug-resistant epilepsy (DRE) where resection isn't viable neuromodulation emerges as a promising alternative. Studies indicate Responsive Neurostimulation (RNS) targeting diverse thalamic nuclei may effectively address multifocal or generalized epilepsy. (1) However, the impact of conversion/addition of RNS leads to thalamic nuclei from a cortical focus in non-responsive cases remains largely unexplored. We studied cases where RNS contacts were converted/added to target the thalamic CM nuclei.
Methods: We reviewed four cases in our series. The first case involves a 26-year-old male with multifocal DRE who underwent conversion of electrodes from left posterior temporal and parietal strips to the left CM and left sensory hand area in March 2022. The second case is a 21-year-old female with Rasmussen encephalitis and hemispheric multifocal epilepsy, where the left frontal opercular strip was disconnected and the left CM was connected in May 2024. The third case is a 13-year-old male with drug-resistant focal epilepsy, where the RNS electrode was converted from the right frontal to the right CM in December 2023. The fourth case involves an 18-year-old with drug-resistant multifocal epilepsy, where the left CM electrode was converted to the right CM in March 2024.
Results: In our first case, the seizure frequency remained relatively unchanged post initial RNS implantation. However, following the connection of the thalamic-CM electrode, there was a decrease in seizure frequency by 90-99%. In the second case following the initial RNS placement, there was a reduction in seizure frequency by 25-49%, with no notable change in seizure severity. However, after connecting the thalamic-CM electrode, there was a reduction in seizure frequency by 50-74% associated with improvement in seizure severity. In the third case, the patient's seizure frequency remained stable or even increased after the initial RNS placement. However, following the connection of the thalamic-CM electrode, there was a significant reduction by 75-89%. In the fourth case, there was a slight decrease in seizure frequency by 1-24% following the initial RNS placement, which included the left CM electrode. Currently, no follow-up appointment has occurred since the electrode switch to the right CM.
Conclusions:
Our limited case series suggests repositioning RNS electrodes to thalamic-CM nuclei may enhance treatment outcomes in non-responders to cortical electrodes. Although the factors influencing response rates aren't fully elucidated, emerging evidence indicates neurostimulation may exert its effects at a network level. Thalamic nuclei, particularly CM, with their extensive connectivity, emerge as attractive targets for disrupting epileptic networks. Further research is warranted to validate these findings and elucidate underlying mechanisms.
References:
1. Ahn S, Edmonds B, Rajaraman RR, Rao LM, Hussain SA, Matsumoto JH, et al. Bilateral centromedian nucleus of thalamus responsive neurostimulation for pediatric-onset drug-resistant epilepsy. Epilepsia 2024; 00:1-10.
2.
Funding: Dr. Eliashiv has grant support and honoraria for talks on neurostimulation from NeuroPace
Clinical Epilepsy