Vagus nerve stimulation in refractory epilepsy: New indications and outcome assessment

•The majority of patients (74%) presented a clear improvement in seizure frequency.•The McHugh classification is more suitable to evaluate the seizure outcome after VNS.•Younger age and focal epilepsy are generally related to a better outcome after VNS.

Although vagus nerve stimulation (VNS) is an effective alternative option for patients with refractory epilepsy unsuitable for conventional resective surgery, predictors of a better control of seizure frequency and severity are still unavailable. This prospective study reports on 39 patients, including 4 children affected by epilepsia partialis continua (EPC), who underwent VNS for refractory epilepsy. The overall seizure frequency outcome was classified into three groups according to reduction rate: ≥ 75%, ≥ 50%, and < 50%. Engel and McHugh classifications were also used. The median follow-up period was 36 months. A seizure reduction rate ≥ 50% or EPC improvement was observed in 74% of the patients. Twenty-one out of 35 cases (60%) resulted in Engel classes II and III. Outcome, as defined by the McHugh scale, showed a responder rate of 71%.These results suggest that younger patient age and focal or multifocal epilepsy are related to a better seizure control and cognitive outcome. Vagus nerve stimulation could also be considered as an effective procedure in severe conditions, such as drug-refractory EPC.