Hypoglossal Nerve Stimulation in Down Syndrome Children: Secondary Outcomes Analyses

Introduction: The safety and efficacy of Hypoglossal Nerve Stimulation (HGNS) in pediatric patients with Down syndrome and persistent obstructive sleep apnea (OSA) following adenotonsillectomy has recently been demonstrated. The primary paper focused on changes in the apnea-hypopnea index (AHI) and QOL scores 12 months post-operatively. The objective of the current project is to examine the impact of HGNS on additional polysomnogram parameters such as the oxygen saturation nadir (O2 nadir) and the ratio of apneas to hypopneas (A/H). We also sought to examine whether select clinical factors such as the Body Mass Index percentile (BMI%) impacted HGNS outcomes in this population.

Methods: Secondary analysis of a multi-institutional cohort study of 42 non-obese children with Down syndrome ages 10-21 years with severe AHI (AHI > 10 and < 50) who were treated with HGNS. Patients were excluded if they had a BMI > 95th percentile at the initial visit. Pre- and 1-year post-HGNS data was evaluated.

Results: The mean (SD) baseline age was 15.1 yrs (3.0), and the mean (SD) baseline AHI was 23.5 (9.7). The mean change in AHI pre/post-HGNS was -51.2% (95% CI: -35.3% to -67.0%. The mean (SD) increase in O2 nadir was 3.2% (4.6%) (95% CI: 1.8%-4.7%). The overall ratio of apnea events to hypopnea (A/H) events decreased from a mean A/H of 2.25 pre to 0.129 post-implantation. BMI% did not correlate with a therapy response, defined either as ≥ 50% reduction in AHI (Pearson’s r of 0.066) or when AHI improvement was calculated as a continuous variable (r of -0.020). Similarly, BMI% correlated poorly with an O2 nadir change pre/post-implantation (r of 0.234).

Conclusions: Pediatric patients with Down syndrome and OSA experience improvements in PSG parameters beyond just the AHI following HGNS. This data also suggests the large median reduction in AHI stems from large reductions in apneas. Furthermore, BMI in our non-obese patients was not correlated with treatment outcomes. Future research is needed to examine HGNS outcomes in a population of obese Down syndrome patients that have persistent OSA and are in the obese category.