VNS treatment in super-refractory status epilepticus: report of two cases and systematic review of literature

Background: super-refractory status epilepticus (SRSE) is a rare and severe neurological condition associated with high mortality and significant long-term morbidity. In many cases, conventional medical treatments prove ineffective, with wide use of off-label therapies. Methods: two researchers conducted a review of the medical records of subjects who had undergone VNS implantation in our tertiary Centre. Additionally, we performed a comprehensive search of the PubMed/MEDLINE and Embase databases. Only manuscripts published in English were included in the review. Results: seventeen studies, encompassing 64 subjects (including the two patients from our series), met the inclusion criteria. The mean age at the time of VNS implantation was 17.3 years, and 52% of subjects admitted for SRSE had a prior history of epilepsy. The mean number of anti-seizure medications used before VNS implantation was 7, with a median duration of the status of 26 days prior to VNS. VNS led to the resolution of SRSE in 84% of subjects (93% of those with convulsive SRSE and 83% with non-convulsive SRSE). In terms of parameters applied, we found the following median values: Amperage: 1.75 mA; frequency: 30 Hz; Pulse Width: 500 uSec; Duty cycle: 16%; Time On: 30 sec and Time Off: 5 min. Conclusion: VNS can be an effective treatment option in individuals with SRSE unresponsive to medical treatment.