Efficacy of vagus nerve stimulation in 95 children of drug-resistant epilepsy with structural etiology

Abstract

Vagus nerve stimulation (VNS) is one of the treatment options for drug-resistant epilepsy (DRE). To analyze the efficacy of VNS in children of DRE with structural etiology, we conducted a cohort study including 95 patients of DRE with structural etiology who underwent VNS treatment. Patients were followed up every 3 months at the outpatient department or via a remote programming platform. The median follow-up period was 2.6 years (range 1.0–4.6 years). The respective responder rates at 6, 12, 18, and 24 months of follow-up were 40.0% (38/95), 52.6% (50/95), 56.0% (47/84), and 59.7% (37/62). The respective seizure-free rates at 12, 18, and 24 months of follow-up were 8.4% (8/95), 9.5% (8/84), and 9.7% (6/62). The patients were divided into four groups based on etiologies: malformations of cortical development (n = 26), post-encephalitic lesions (n = 36), perinatal brain injury lesions (n = 31), and hippocampal sclerosis (n = 2). The respective responder rates at 12 months of follow-up in these groups were 53.8% (14/26), 52.8% (19/36), 51.6% (16/31), and 50.0% (1/2). There were no significant differences in gender, age at onset, age at stimulator implantation, epilepsy duration prior to VNS implantation, number of anti-seizure medications ever tried before VNS treatment, pulse amplitude of VNS, specific structural etiologies, lobe distribution or hemispheric side of structural lesions between responders and non-responders. Of the 95 patients, 8 (8.4%) underwent lesion surgery or hemispherectomy before VNS implantation, and 6/8 (75%) of these patients had a >50% reduction in seizure frequency. One patient who had a corpus callosotomy before VNS implantation had no response to VNS treatment. In conclusion, VNS is an effective treatment in children of DRE with structural etiology. There was no significant difference in VNS efficacy in patients with different structural etiologies. Vagus nerve stimulation treatment may also control seizures well in some patients with poor outcomes after lesion resection or hemispherectomy before VNS implantation.