Upper airway stimulation, also known as hypoglossal nerve stimulation or HGNS, represents an important therapeutic option for adults with moderate to severe obstructive sleep apnea who cannot tolerate or achieve adequate benefit from positive airway pressure therapy such as CPAP. A newly published study examines how treatment outcomes with this approach differ according to sleep position and patient sex, offering valuable data for clinicians and researchers alike.

Background on Obstructive Sleep Apnea and Upper Airway Stimulation

Obstructive sleep apnea, commonly abbreviated as OSA, occurs when the upper airway repeatedly collapses during sleep, leading to pauses in breathing, fragmented sleep, and drops in blood oxygen levels. The apnea-hypopnea index, or AHI, measures the number of these events per hour of sleep, with moderate to severe cases typically defined as an AHI of 15 or higher. Traditional first-line treatment involves continuous positive airway pressure devices, yet adherence remains a significant challenge for many patients.

Upper airway stimulation via the hypoglossal nerve provides an alternative by delivering electrical impulses to the nerve that controls tongue movement, thereby preventing airway collapse. The therapy requires surgical implantation of a device, usually performed by otolaryngologists or sleep medicine specialists. Patients activate the device nightly via a remote, and therapy effectiveness is assessed through follow-up sleep studies measuring changes in AHI and other parameters.

OSA severity often varies with body position, with events frequently worsening in the supine position due to gravity's effect on the tongue and soft tissues. Sex differences also play a role, as men and women exhibit variations in airway anatomy, fat distribution, arousal thresholds, and symptom presentation. These factors can influence both disease manifestation and response to interventions.

The Research Team and Publication Details

The study, titled "Upper Airway Stimulation for Obstructive Sleep Apnea: Treatment Outcomes by Sleep Position and Sex," was conducted by a team of researchers including Alexis C. Shindhelm, Alan R. Tesson, Emily A. Commesso, Shakthi Unnithan, Russel R. Kahmke, Matthew D. Ellison, Hussein R. Al-Khalidi, Stephen V. Gliske, and Rodney A. Radtke. It appears in the journal Sleep Medicine and is available via the ScienceDirect platform at https://www.sciencedirect.com/science/article/abs/pii/S138994572600331X. An abstract was also presented in the SLEEP 2026 meeting supplement.

This work builds on earlier pivotal trials of hypoglossal nerve stimulation, such as the STAR trial, which established the therapy's safety and efficacy in selected patients. The current analysis focuses specifically on positional and sex-based variations in outcomes, addressing gaps in personalized treatment approaches.

Study Design and Patient Cohort

Researchers reviewed data from 181 patients who underwent device implantation. After applying inclusion criteria, 113 patients were analyzed. The cohort was predominantly older adults with a median age of 65 years, overweight with a median body mass index of 30, and mostly White (91.2 percent). Males comprised 67.3 percent of the group, and baseline OSA was severe with a median AHI of 32 events per hour.

Patients were categorized into sleep-position cohorts based on predominant sleeping posture during testing. Success was evaluated using two main metrics: the Sher criteria, which requires at least a 50 percent reduction in AHI and a post-treatment AHI below 20 events per hour, and AHI normalization, typically defined as AHI less than 5 or 10 events per hour depending on the specific threshold applied in the analysis.

Subgroup analyses considered fixed-voltage home sleep apnea tests, though these were noted as underpowered due to smaller sample sizes in certain categories.

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Key Findings on Sleep Position

Treatment success rates differed markedly between lateral and supine sleep positions. In the lateral sleep cohort, success by Sher criteria reached 77.0 percent, compared with 52.9 percent in the supine cohort. AHI normalization occurred in 54.1 percent of lateral sleepers versus 23.5 percent of supine sleepers.

These results indicate that hypoglossal nerve stimulation controls OSA more effectively when patients sleep on their side. The positional dependency aligns with known physiology, where supine positioning exacerbates airway collapsibility. Clinicians may use this information when counseling patients about expected outcomes or considering adjunctive positional therapies alongside stimulation.

Key Findings on Sex Differences

Female patients demonstrated superior outcomes across multiple measures. Women achieved significantly higher success rates by both Sher criteria and AHI normalization compared with men. Additionally, females experienced a greater reduction in supine AHI scores, with statistical significance confirmed through Wilcoxon rank-sum and chi-square tests.

These sex-based differences suggest that biological factors, including variations in upper airway anatomy and muscle responsiveness, may contribute to enhanced therapy response in women. The findings support a more nuanced approach to patient selection and expectation setting in sleep medicine practice.

Broader Context of OSA Treatment and Research

Hypoglossal nerve stimulation has gained acceptance as a second-line option following position statements from professional organizations such as the American Academy of Otolaryngology-Head and Neck Surgery. Long-term data from earlier cohorts show sustained benefits in AHI reduction and patient-reported outcomes like sleepiness and quality of life, with low rates of serious adverse events.

General sex differences in OSA are well documented in the literature. Women often present with lower overall AHI but higher rates of symptoms at equivalent severity levels, partly due to differences in arousal threshold and airway collapsibility. Research on other therapies, including oral appliances, has similarly noted potential advantages for female patients in certain contexts.

The current study adds granularity by focusing on an implantable therapy and incorporating objective positional data. It complements broader efforts in sleep medicine to move toward precision approaches that account for individual patient characteristics.

Implications for Clinical Practice and Future Research

The observed differences by sleep position and sex carry practical implications. Providers might discuss positional tendencies with patients prior to implantation and consider whether additional interventions, such as positional trainers, could optimize results for supine-predominant cases. For female patients, the data may support more optimistic counseling regarding expected AHI reductions, particularly in supine sleep.

Limitations of the study include its retrospective nature, reliance on available sleep study data, and relatively homogeneous demographic profile. Larger, prospective studies across diverse populations would strengthen generalizability. Future investigations could explore interactions between position, sex, body mass index, and other comorbidities to refine predictive models.

From an academic perspective, this publication underscores the value of detailed secondary analyses of existing clinical datasets. Such work often emerges from collaborative efforts at university-affiliated medical centers and contributes to the evidence base that informs guidelines and training in otolaryngology and sleep medicine programs.

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Advancing Sleep Medicine Through Academic Research

Publications like this one highlight ongoing innovation in the management of chronic conditions that affect millions worldwide. Researchers continue to examine mechanisms of airway patency, device optimization, and patient selection criteria. Academic institutions play a central role in conducting these studies, training the next generation of sleep specialists, and translating findings into improved patient care.

Opportunities exist for graduate students, postdoctoral fellows, and faculty in fields ranging from biomedical engineering to clinical neurology to contribute to this evolving area. Multi-center registries and advanced analytics, including machine learning applied to polysomnography data, represent promising directions for future inquiry.

Patient Considerations and Next Steps

Individuals considering upper airway stimulation should undergo comprehensive evaluation, including drug-induced sleep endoscopy to assess airway collapse patterns. Candidacy typically requires moderate to severe OSA, intolerance to positive airway pressure, and absence of certain anatomical contraindications.

Post-implantation follow-up involves titration of stimulation settings and repeat sleep testing to confirm efficacy. Patients are encouraged to maintain open communication with their care team regarding any positional habits or changes in symptoms.

Resources from reputable organizations provide additional education on OSA and available therapies. Continued research will likely refine indications and enhance outcomes across diverse patient groups.