Clinical experience implanting a miniature externally powered vagus nerve stimulator

Vagus nerve stimulation (VNS) is widely used to treat various neurological and psychiatric conditions, including epilepsy and treatment-resistant depression, as well as to enhance motor rehabilitation following stroke. Conventional VNS devices have demonstrated reliability over decades of use, though recent advancements in technology offer new opportunities to further enhance the device. Many emerging indications require only intermittent stimulation, allowing for the development of a miniature externally powered implantable stimulator (MEPS) that is approximately 50 times smaller than conventional devices, is implanted with a single incision, has no battery or leads, and enables paired stimulation. Our observations compiled from three clinical trials with the MEPS device tested the hypotheses that removing the implanted battery and reducing device size would (1) shorten the surgical procedure and (2) maintain or improve safety outcomes. Data were collected from individuals with stroke, spinal cord injury, or post-traumatic stress disorder. Operative time was significantly reduced, averaging 38 ​± ​1 ​min compared to 76 ​± ​3 ​min for conventional VNS, with no significant intraoperative complications and no revision surgeries. The MEPS device successfully delivered 481,995 stimulations during 2205 ​h of therapy. One participant underwent an MRI outside the study, indicating compatibility with standard imaging protocols. Device-related adverse events occurred at a low rate; all were mild and resolved before study end. Overall, the MEPS device demonstrated a favorable safety and performance profile in a select population, with fewer occurrences of certain adverse events, extending the strong safety record of conventional VNS systems.