Vagus Nerve Stimulation: Seizure Reduction in Medically Refractory Epilepsy

Objective: The aim of this study is to define seizure response, seizure reduction rates and possible factors associated with a good outcome. Background: Vagus Nerve Stimulation (VNS) is a device approved for seizure management in patients with refractory focal epilepsy. Many studies were conducted with a variability of responses in seizure reduction. Design/Methods: We interrogated the database of the epilepsy program at the London Health Science Centre, searching for VNS implantations in patients with medically resistant epilepsy since the VNS was available in Canada (1997) to September 2018. Results: A total of 114 patients were included. The median age of VNS implantation was 34.4 years old (IQR=1.5–64) and the age of implantation was 26.5(IQR=20–34). 56.1%(N=64) of patients were male. 27%(N=31) had generalized epilepsy and the most common etiology was unknown in 27%(N=31). The number of antiseizure medications at the time of the implantation was 3(IQR=2–3) and the frequency of seizures was 25(IQR=8.7–60). The median follow-up period was 46 months after the implantation. The seizure rate reduction was −68.2%(IQR=(−92.6%)–(−37.1%)) after the VNS was implanted and 56%(N=41) had a seizure reduction equal or higher than 50%. The type of seizures with a significant seizure reduction (p Conclusions: VNS is a relatively safe therapy as an adjutant therapy in patients with medically resistant epilepsy, with a good response in more than a half of the patients. The patients with generalized and bilateral tonic-clonic seizures show the greatest improvement from VNS. Disclosure: Dr. Suller Marti has nothing to disclose. Dr. McLachlan has nothing to disclose. Dr. Mirsattari has nothing to disclose. Dr. Steven has nothing to disclose. Dr. Parrent has nothing to disclose. Dr. Andrade has nothing to disclose. Dr. deRibaupierre has nothing to disclose. Dr. Diosy has nothing to disclose. Dr. MacDougall has nothing to disclose. Dr. Burneo has nothing to disclose.