P.011 Is the effect of the vagus nerve stimulation different in lesional and nonlesional medically resistant epilepsies?

Background: The incidence of drug resistant epilepsy (DRE) is around 30% patients with epilepsy. Vagus nerve stimulation (VNS) is offered to patients who are not candidates for epilepsy resective surgery, however the results of lesional cases has not been explored previously Methods: The study was a retrospective cohort study that involved patients with DRE implanted with VNS at the Epilepsy program at Western University, Ontario. We classified our VNS cohort based on brain imaging of lesional (L) and nonlesional (NL) epilepsy. Results: The median age was 31.8 years, 70.69% were females. The VNS-L group average age was 31.8 years and the NL 35.2 years. The most common abnormality was nodular heterotropias 31.34% (n=9). 16 patients underwent palliative procedures before the VNS implantation, 12 in VNS-L and 4 in VNS-NL. The median period of follow-up was 69.97 months. 62% of the VNS-L group had a seizure reduction of 50% or greater, compared to 41.38% in the VNS-NL group. Seizure freedom was 10.34% in VNS-L, compared to 6.99% in VNS-NL. Conclusions: This is the first study reporting the outcome of VNS in lesional cases. Our results suggest that VNS in lesional cases is effective. However, a large multicenteric study is needed.