0631 Mandibular Protrusion Range (MPR) as a Predictor of Outcome in Hypoglossal Nerve Stimulation Therapy for Obstructive Sleep Apnea

Abstract Introduction Increased MPR may be associated with posterior mandibular collapse during supine sleep, producing a more obstructed airway geometry that demands larger genioglossus displacement (and therefore higher stimulation voltage) for airway patency, leading to smaller reductions in AHI and ESS. Greater mandibular protrusive range (MPR) has been associated with improved responsiveness to mandibular advancement devices (MADs) in obstructive sleep apnea (OSA). However, the role of MPR in predicting outcomes of hypoglossal nerve stimulation (HGNS) therapy has not been evaluated. Patients with mandibular protrusion range (MPR) ≥ 5 mm require higher stimulation voltage to achieve optimal tongue advancement and will show less improvement in daytime sleepiness (ESS) after hypoglossal nerve stimulation therapy than patients with MPR < 5 mm, because posterior displacement/collapse of the mandible in supine sleep increases the mechanical work needed to clear the airway. Methods We conducted a retrospective review of 34 consecutive patients treated with HGNS who also had cephalometric measurements, including MPR, obtained during clinical evaluation. Patients were followed for 3 months with titration of stimulation amplitude until patient-reported benefit limited further increases. Collected data included baseline OSA severity, HGNS amplitude settings, Epworth Sleepiness Scale (ESS) scores, demographic characteristics, and adherence. Results Twenty-two patients demonstrated an MPR ≥ 5 mm, while 12 had MPR < 5 mm. Patients with higher MPR had similar baseline daytime sleepiness (ESS 10.36 ± 5.17 vs 8.42 ± 5.37). At 3 months post HHNS therapy, patients with MPR ≥ 5 mm showed no significant difference in ESS (8.86 ± 4.65 vs 7.25 ± 4.65) or stimulation amplitude (1.09 ± 0.63 vs 1.22 ± 0.57) as compared to patients with MPR< 5 mm. No differences in therapy adherence were observed between groups. There were no differences in demographics and baseline characteristics in the two groups either. Conclusion In this study, mandibular protrusion range (≥5 mm vs < 5 mm) was not associated with differences in postoperative ESS improvement or required stimulation voltage, indicating that MPR — at the 5 mm cutoff — is not a reliable independent predictor of therapeutic response or programming intensity for HNST. Support (if any)