Optimizing vagus nerve stimulation for Super Refractory Status Epilepticus: A case series and systematic review

Super Refractory Status Epilepticus (SRSE) is a neurological emergency characterized by a status epilepticus that persists or recurs despite 24 h of treatment with anesthetic therapy (A-T). Vagus Nerve Stimulation (VNS) is a well-established treatment for drug-resistant epilepsy (DRE). In this study, we explore the safety and efficacy of VNS for SRSE. A database search was conducted until August 14, 2024 to identify patients who were implanted with a VNS as a surgical neuromodulation therapy for SRSE. We report on the etiology of SRSE, previous DRE diagnosis, VNS parameters required for SRSE resolution, and long-term outcomes. Out of 257 screened studies, 24 met inclusion criteria, encompassing 30 published cases. Alongside 3 institutional cases, our study analyzed 33 patients. VNS was associated with SRSE resolution in 29/33 patients (87.87%). Median age at surgery was 15 years (range: neonate to 67 years). Seventeen had prior DRE diagnoses. Days on A-T before implantation ranged from 5 to 420 (median 25, IQR 12-42.5). Median VNS output for resolution was 1.375 milliamperes (mA) (IQR = 1-1.75), with 1 mA being the most common setting (11/30, 36.6%). Median time to reach therapeutic VNS parameters was 2 days (IQR = 1.25-7.75). SRSE resolved at a median of 7 days post-op 7 (IQR: 4.75-14). At follow-up of DRE patients, McHugh scores were as follows: 1 (8/15, 53.3%), 2 (4/15, 26.6%), 3 (1/15, 6.6%), and 5 (2/15, 13.3%). VNS was associated with SRSE resolution in 87.87% of cases. Based on available observational data, VNS may be considered for SRSE after 2 weeks of treatment nonresponse. Proposed titration strategies to reach ≥1 mA include immediate (within 20 min post-op), rapid (within 24-36 h), and accelerated (within 2 weeks). Titration should be individualized based on SRSE duration and patient tolerance. Further studies are needed to define the role of VNS in SRSE.