Vagal nerve stimulation in intractable epilepsy: clinical experience on 100 patients and review of the literature

Abstract

Introduction: Vagus Nerve Stimulation (VNS) is an effective alternative treatment for patients with refractory epilepsy. Nevertheless, information regarding VNS is still limited. Materials and Methods: In the present non randomized, prospectic study we report our clinical safety and effectiveness of VNS in 100 patients (52 Males and 48 Females) with drug resistant epilepsy. Patient's age at implant ranged from 0,64 to 51,04 years (mean age 15.3 years). The mean follow-up time was 54,8 months ( range 2 to 108,3 months). Seventeen patients suffered from Lennox-Gastaut Syndrome, 34 patients suffered from partial epilepsy with drop attacks and secondary bysinchronism on the EEG (Lennox Gastaut-like) and 49 patients had Partial Epilepsy without drop attacks. Data collection forms were designed for prospectively gathering data on each patient's history, seizures, drug therapy, implant device settings and side effects. Patients were assessed prior the implant and 3, 12 and 24 months after surgery. Results: Seventy-eight patients completed the 24 months follow-up session. VNS produced a mean seizure rate reduction of 32% at 3 months, 41% at 12 months, and 45% at 24 months. At 24 months, only the Partial Epilepsy patients showed a seizures reduction of 50%, which is considered clinically significant. Moreover both the age at implant and epilepsy duration were inversely correlated with the percentage of seizure reduction at 24 months. Side effects were minor and transient; the most common were voice alteration and coughing during stimulation. In 7 patients electrode breakage occurred three years after the surgical procedure. Conclusion: In our study, clinical effectiveness is higher in younger children implanted before than 12 years with shorter epilepsy duration suggesting a precocious useful role of VNS. Patients with Lennox Gastaut Syndrome show a worse clinical response rather than other epileptic syndromes.

Keywords

• vagal nerve stimulation (VNS), epilepsy, children, efficacy, safety