Is Deep Brain Stimulation Effective in Epileptic Patients’ Refractory to Vagal Nerve Stimulation?

Introduction: Epilepsy syndromes that are refractory to AEDs are often controlled with several neuromodulation techniques such as Deep brain stimulation, Vagus Nerve Stimulation, and Responsive Neurostimulation. Resection surgery, although highly effective, is not always feasible. These neuromodulation techniques are thereby employed when candidates do not meet the criteria for surgery. There have been studies detailing each of these techniques and their various advantages in drug-refractory epilepsy. There are few studies on DBS after failed VNS in epileptic patients.

Methods: Using a preset search strategy, databases (PubMed, Google Scholar, Embase, Scopus, and Science Direct) were searched to identify relevant studies published up until June 2024. Title and abstract screening using a set of inclusion and exclusion criteria was carried out by two independent reviewers and any disagreement was settled by an independent third party. Full-text screening and data extraction were done simultaneously.

Results: 13 articles including 72 cases were included. The anterior nucleus of thalamus DBS (ANT-DBS) was the most common, followed by the centromedian nucleus of thalamus DBS (CM-DBS) at 24.6%, and substantia nigra/subthalamic nucleus DBS (SNr/STN DBS). Additional seizure surgeries were uncommon as most participants (92%) had not undergone any other types of seizure surgery. The effectiveness of DBS after VNS was measured by the reduction in seizure frequency at the last follow-up, which showed a mean reduction of 63.1%.

Conclusion : Generalized epilepsy syndromes respond to DBS, where VNS has failed. ANT-DBS is specifically effective in FIA seizures. DBS has successfully reduced seizure frequency and duration in many patients, with tolerable side effects that can be reduced with voltage modification.