Responsive Neurostimulation (RNS) of Thalamic Nuclei in Pediatric Drug Resistant Epilepsy (DRE): Updated Outcomes
Abstract number :
2.141
Submission category :
4. Clinical Epilepsy / 4C. Clinical Treatments
Year :
2022
Submission ID :
2204092
Source :
www.aesnet.org
Presentation date :
12/4/2022 12:00:00 PM
Published date :
Nov 22, 2022, 05:23 AM
Authors :
Deepankar Mohanty, MD – Baylor College of Medicine; Kimberly Houck, MD – Assistant Professor, Pediatrics - Neurology, Baylor College of Medicine, Texas Children's Hospital; James Riviello, MD – Professor, Pediatrics - Neurology, Baylor College of Medicine, Texas Children's Hospital; Daniel Curry, MD – Professor, Neurosurgery, Baylor College of Medicine, Texas Children's Hospital; Irfan Ali, MD – Assistant Professor, Pediatrics - Neurology, Baylor College of Medicine, Texas Children's Hospital
Rationale: Responsive neurostimulation (RNS) is an FDA-approved form of neuromodulation to treat patients with drug-resistant epilepsy (DRE) who are ineligible or refractory to surgical treatment. However, the FDA approval only applies to patients with one or two epileptogenic foci, which would be used as the target location(s) for neurostimulation. The population of patients with multifocal, regional, or non-localizable DRE may also benefit from application of the RNS system. Recent literature has shown possible efficacy (in terms of seizure reduction) of thalamic RNS stimulation in a small number of patients with Lennox-Gastaut syndrome (LGS) and multifocal epilepsy, particularly targeting the centromedian nucleus (Kwon et al, Ann Clin Transl Neurol., 2020). We hypothesized that responsive neurostimulation of thalamic nuclei may be effective in seizure reduction for patients with multifocal or non-localizable DRE, with or without LGS. We had previously reviewed the outcomes for several such pediatric patients at Texas Children’s Hospital after thalamic RNS implantation; the purpose of this study is to provide an update after another year of patient recruitment and follow-up.
Methods: We performed a retrospective chart review of all patients (aged 6-22) who had an RNS device implanted at Texas Children’s Hospital between July 2016 and May 2022, with at least one active stimulating electrode in the thalamus. RNS settings and electrode locations were acquired from device diagnostics. Change in clinical seizure frequency was calculated based on the difference between pre-implantation baseline and the most recent follow up visit, as reported by patient’s caregiver. Responder rate was defined as ≥ 50% reduction in seizure frequency from pre-implantation baseline. Changes in quality of life (QOL) and seizure severity were reported on a 5 point scale by caregiver at post-implantation follow up.
Results: Twelve (12) patients had active RNS depth) electrodes implanted in thalamic nuclei during the period specified. Eleven (11) patients had stimulation electrodes placed in the centromedian nuclei, and 1 in the anterior nucleus. Maximum stimulation charge density ranged from 0.5 to 2.5 µC/cm2. After at least 6 months of follow up, 50% (6/12) reported ≥ 50% reduction in seizure frequency (1 patient reported full seizure freedom, 4 reported 75%-99% reduction, and 1 reported 50%-74% reduction). Four (4) of those patients completed surveys and all reported subjective improvement in seizure severity and QOL. There were 4 patients who reported no change in seizure frequency, severity, or QOL. Notably, 3 of them (75%) had ≥ 10 seizures per day pre-implantation, whereas none of the responders met this threshold (average pre-implantation seizure burden = 2.7/day).
Conclusions: Responsive neurostimulation of thalamic nuclei is a neuromodulation technique that shows promise in improving seizure frequency and severity in some pediatric patients with multifocal or non-localizable DRE. Response rates may be higher in patients with lower seizure burdens pre-implantation, but further follow-up and patient recruitment is needed to determine relevant factors.
Funding: None
Clinical Epilepsy