Evaluation of the outcomes of vagal nerve stimulation in children with drug-refractory epilepsy in South Africa

PURPOSE: To evaluate the clinical outcomes of vagal nerve stimulation (VNS) in children with drug refractory epilepsy (DRE) in a Sub-Saharan setting. METHODS: We retrospectively reviewed the data of 93 paediatric patients with DRE who underwent VNS insertion between January 2008 and December 2022. Patient demographics, aetiology of epilepsy and seizure data were analyzed. Seizure outcomes were measured using the Engel, McHugh, and Hague scores. Statistical analysis was performed using the Chi-square test, T-tests, and Spearman's correlation. RESULTS: Of the 93 patients who underwent VNS implantation 60% achieved a seizure reduction of at least 50%. Demographic factors associated with improved seizure control included age at implantation (p < 0.001) and shorter duration from first reported seizure to implantation (p < 0.001). The mean time to response was 6.9 months. The McHugh scale showed a significant association between the length of follow up and VNS response. Adverse effects of VNS insertion were limited. Our outcome data and complication rates were in line with previous studies from the developed world. Challenges unique to our population included delay from diagnosis to referral; on average, there was a 5-year period from diagnosis of DRE to referral to our center. In addition to the large population and our extensive geographic referral pattern, we identified that a key factor in delayed referral to our center was due to a poor awareness, amongst both caregivers and referring clinicians of VNS as a treatment option for DRE. CONCLUSION: VNS is a safe and effective adjunctive treatment for children with DRE in the Sub-Saharan population, with results comparable to centers in the developed world. In our cohort of patients, the McHugh scale appeared to be a more sensitive tool for assessing and tracking VNS response.