Hypoglossal Nerve Stimulation in Obstructive Sleep Apnea With Complete Concentric Collapse

This prospective, single-center, open-label investigational cohort will enroll up to 20 adults with obstructive sleep apnea and complete concentric collapse of the soft palate on clinically obtained drug-induced sleep endoscopy. Research assessments occur at Brigham and Women's Hospital; implantation occurs at Massachusetts Eye and Ear. Investigational implantation is conducted under FDA IDE G260193. All enrolled participants receive the intervention; there is no randomization or separate treatment comparison arm. Baseline eligibility requires attended laboratory polysomnography before implantation. A suitable recent clinical polysomnogram may be used; otherwise a research polysomnogram is obtained after consent. Activation is approximately four weeks after implantation and titration approximately three months after implantation. HGNS-on sleep testing and questionnaires occur approximately one month after titration, targeting completion by six months after implantation, and again at 12 months. Follow-up testing may use laboratory polysomnography or the Nox A1 home sleep testing system. At 4-12 months after implantation, once device settings are stable, participants undergo a dedicated physiological sleep study following four nights without HGNS. Critical closing pressure is measured during brief CPAP pressure drops with HGNS off and on. During the second portion of the night, HGNS is off and airflow and intraesophageal diaphragm electromyography are used to characterize physiological traits. Participants also complete seven days of wearable ring monitoring; device downloads at the first in-laboratory visit 4-12 months after implantation quantify adherence. The CCC cohort provides within-participant physiological and clinical response estimates. Prespecified pooled analyses combine these data with a separately enrolled standard-of-care non-CCC cohort. The primary pooled mechanistic comparison evaluates HGNS-induced changes in critical closing pressure between lateral collapse (CCC or complete oropharyngeal lateral wall collapse) and predominantly anteroposterior collapse. Companion-study participants are not included in this registration's enrollment. Exploratory analyses assess physiological traits, treatment response, adherence, and prediction of clinical success. An independent Data and Safety Monitoring Board reviews safety and treatment response. New enrollment and implantation pause after the first ten implants pending the required response checkpoints and DSMB review. Safety follow-up continues through 12 months after implantation, with continued follow-up of unresolved events as needed.