0552 Radiographic Predictors of Response to Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea

Abstract

Introduction: Hypoglossal nerve stimulation (HGNS) is a novel therapy for PAP-intolerant patients with obstructive sleep apnea. As therapy response rate (> 50% reduction of AHI and AHI < 20 events/ hour) remains roughly 60%, patient selection is key. In this study, we sought to determine the predictive value of cephalometric measurements utilizing lateral neck x-rays of HGNS-implanted patients. Method(s): In this combined prospective cohort study and retrospective chart review, subjects were adults with AHI > 15 events/ hour who underwent HGNS at the Emory Sleep Surgery Center between 9/2015 and 10/2018. Eligible subjects had diagnostic preoperative sleep studies, full-night efficacy postoperative studies and lateral neck x-rays available for analysis. Subjects with severe body rotation on x-ray were excluded. The Student's t test was used to compare values between groups. Result(s): Forty-four subjects met all criteria. Subjects were predominantly Caucasian males with mean age 62.8 years, BMI 28.8 kg/ m2 and baseline AHI 38.1 events/hour. The overall response rate was 45% with no significant baseline differences between responders (n = 20) and non-responders (n = 24). Responders achieved a greater mean AHI reduction than non-responders (31.1 +/- 13.1 vs. 5.9 +/- 21.4, p < 0.01). There were no significant differences between responders and non-responders in soft palate length (5.5 +/- 1.1 vs. 5.1 +/- 0.8, p = 0.28), soft palate thickness (1.4 +/- 0.4 vs. 1.6 +/- 0.4, p = 0.25), soft palate area in millimeters2 (698.6 +/- 228.6 vs. 701.9 +/- 193.0, p = 0.97), mandibular plane to hyoid distance (3.6 +/- 1.4 vs. 3.4 +/- 1.2, p = 0.58), mandibular length (15.9 +/- 24.7 vs. 9.9 +/- 1.5, p = 0.38) or posterior nasal spine to C1 vertebral body distance (4.3 +/- 0.7 vs. 4.4 +/- 0.7, p = 0.72). Measurements were obtained in centimeters unless otherwise noted. Conclusion(s): This is the first study to investigate the predictive value of key cephalometric variables in HGNS-implanted patients utilizing lateral neck x-ray. Although underpowered, there were no significant differences in palatal or skeletal measurements between responders and non-responders.