Vagus nerve stimulation for patients with refractory epilepsy

Objectives: Vagus nerve stimulation (VNS) is an established adjunctive therapy for medically refractory epilepsy, which is commonly associated with cognitive impairment, especially in children in whom seizures may disrupt development that is essential to their intellectual and social maturation. The Taiwan Child Neurology Society intends to expand the use of VNS by reporting the experience in a nationwide population, displaying the demographic features and neuropsychological outcomes of VNS. Methods: The enrollment included 105 patients of all ages and seizure types who underwent VNS implantation for refractory epilepsy. Basic data included etiology, past history, seizure phenotypes, and epileptiform syndromes. For efficacy analysis, seizure frequencies were recorded at the baseline and at 3, 12, 24, and 36 months after VNS implantation. For psychological assessment, intelligence quotients (IQ) and Parental Stress Index (PSI) scores were evaluated before and after the VNS. Results: During the study period, 95 patients with VNS had followed seizure frequency, IQ and PSI recording. After implantation, there was a decreased frequency at 3 (P < .001), 12 (P < .001), 24 (P = .010), and 36 (P < .01) months. After implantation, the reduction rate (0–50%) of seizure frequency ranged around 26.1–36.1% from 3 to 36 months. For PSI scores, the VNS significantly improved the PSI- total score (P = .001) and PSI-parent domain (P = .001) but not the PSI-children domain (P = .052). No significant improvement in the IQ test performance was observed. Conclusions: This prospective nationwide database of VNS in Taiwan indicates long-term efficacy of VNS therapy, which has achieved a trend of seizure frequency reduction over a period of up to 36 months. It also shows the trend of decreased parental stress after VNS implantation.