Utilizing Volume of Tissue Activation Modeling in Centromedian Nucleus of the Thalamus Responsive Neurostimulation: A Case Study
Abstract number :
3.42
Submission category :
18. Case Studies
Year :
2023
Submission ID :
1189
Source :
www.aesnet.org
Presentation date :
12/4/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Trey Jouard, MS – University of Colorado School of Medicine
Jacob Pellinen, MD – Assistant Professor, Neurology, University of Colorado School of Medicine; Lesley Kaye, MD – Assistant Professor, Neurology, University of Colorado School of Medicine; John Thompson, PhD – Associate Professor, Neurosurgery, University of Colorado School of Medicine
Rationale:
Recent meta-analysis and case series have shown responsive neuromodulation (RNS) in the centromedian nucleus of the thalamus (CM) is a promising surgical treatment for the subset of patients with genetic generalized epilepsy (GGE) who have failed anti-seizure medication trials. While use of thalamic neuromodulation has been well established for medically refractory focal epilepsy, our understanding of ideal stimulation parameters is still an area of ongoing research. In this case study we aim to demonstrate a potential strategy by repurposing open source software developed for movement disorders to better identify the optimal stimulation parameters that contribute to CM neuromodulation efficacy in seizure control.
Methods:
The subject of this case study is a right-handed male with a six year history of medically refractory GGE who underwent bilateral implantation of RNS leads in CM. Utilizing brain imaging collected during standard clinical care, the Lead-DBS software was employed to reconstruct the lead placements from pre and post operative MRI and CT scans and to simulate stimulation, creating a Volume of Tissue Activation (VTA) for each lead. Custom software was developed to visualize and quantify the overlap of each VTA with the thalamic nuclei. Thalamic nuclei were identified using the Thomas Atlas. Seizure rates were then correlated with the percentage overlap of the VTA, based on both retrospective chart review and recorded RNS electrocorticography (ECog) data.
Results:
Initial review of pre and post operative imaging data confirmed successful placement of bilateral RNS leads in the CM of the thalamus. A VTA with a 0.5 µC/cm² charge density calculated from the patient’s grouped bipolar stimulation settings had significant overlap with the CM the ventral posterolateral nucleus (VPL) of the thalamus. Further analysis of correlation between the VTA overlap with thalamic nuclei and seizure frequency is ongoing.
Conclusions:
This case study emphasizes the potential of Lead-DBS software to model VTA thalamic implantation for epilepsy. Broader application of this methodology in larger scale studies could contribute to our understanding of why thalamic and specifically CM stimulation can control seizures. While the ideal stimulation parameters for thalamic neuromodulation in epilepsy are yet to be established, reconstructed models may expedite the identification of critical areas and networks for stimulation targeting, ultimately improving patient outcomes in medically refractory GGE.
Funding: None
Case Studies