OBJECTIVES: To assess the impact of body mass index (BMI) on hypoglossal nerve stimulator (HNS) implantation outcomes in pediatric patients with Down syndrome (DS). We compare outcomes of HNS implantation when comparing children based on overweight or obese status. METHODS: Retrospective cohort study of patients at a single tertiary pediatric hospital who underwent HNS implantation between 2022 and 2024. Patients with DS under 21 years of age at time of implantation were included. One child with Wolf-Hirschhorn syndrome was also included. The main outcome measured was reduction in apnea-hypopnea index (AHI). RESULTS: Twenty patients were implanted with HNS during the study period. Eleven patients were implanted with a BMI considered overweight and 8 patients with a BMI considered obese. No significant correlation was found between BMI percentile and AHI reduction (r = 0.06, p = 0.8). No significant differences were found between obese and non-obese groups for preoperative AHI, postoperative AHI, or AHI reduction. Both groups responded favorably to HNS therapy with AHI reduction of 83.8% in obese patients and 81.9% in non-obese patients. CONCLUSION: We demonstrate no difference in postoperative AHI outcomes when comparing patients with obesity defined as BMI >
95th percentile compared to those without. LEVEL OF EVIDENCE: 3 Laryngoscope, 135:1223-1226, 2025.