Vagus Nerve Stimulation Therapy for Patients with Persistent Seizures after Epilepsy Surgery

Abstract

Background: This study reports the effectiveness of vagus nerve stimulation (VNS) among patients who failed cranial surgery for intractable epilepsy. Methods: Data were obtained from the Cyberonics VNS therapy patient outcome registry. The integrity of the systems for collecting and processing registry data was authenticated by an independent auditing agency. Results: Two nonconsecutive cohorts were compared: patients who had had prior cranial surgery (CS group, n = 921) and those who had not (non-CS group, n = 3,822). For the CS group, the median reduction in seizure frequency was 42.5% after 3 months of VNS therapy, 42.9% at 6 months, 45.7% at 12 months, 52.0% at 18 months and 50.5% at 24 months. For the non-CS group, analogous rates were 47.0, 52.9, 60.0, 62.7 and 66.7%, respectively. Conclusion: The effectiveness of VNS is maintained during prolonged stimulation. Patients who failed prior cranial surgery did not respond quite as favorably as all other patients receiving VNS therapy.