Proximal Hypoglossal Nerve Stimulation Offers Sustained Relief for Obstructive Sleep Apnea
Proximal hypoglossal nerve stimulation (pHGNS) provides lasting, safe, and effective improvements in obstructive sleep apnea (OSA), sleep architecture, and quality of life for up to three years, according to recent research published in Chest. The findings build upon earlier studies demonstrating the benefits of this therapy.
Understanding the THN3 Trial
Researchers analyzed three-year outcomes from the phase 3, randomized controlled Targeted Hypoglossal Nerve Neurostimulation trial (THN3; NCT02263859). The study enrolled participants with moderate to severe OSA, defined as an apnea-hypopnea index (AHI) between 20 and 65 events per hour and a body mass index (BMI) of 35 kg/m2 or less.
Participants received an implantable pulse generator and a 6-contact circumferential pHGN lead. They were then randomized to have the device activated either one month or four months post-implantation. Follow-up assessments, including sleep studies, were conducted annually for three years.
Long-Term Safety and Efficacy
Of the 138 participants initially enrolled in the THN3 trial, 104 (75.4%) completed the three-year follow-up, with 98 (71%) undergoing endpoint sleep studies. The results demonstrated sustained improvements in sleep-disordered breathing, oxygenation, and quality of life at both 24 and 36 months compared to baseline measurements.
Throughout the study period, 13 serious adverse events were identified as potentially related to the study, procedure, or device. The most common events were device explant (4 cases) and additional OSA surgery (5 cases).
Improvements in sleep architecture mirrored the improvements observed in AHI. Patient-reported outcomes, measured using the Epworth Sleepiness Scale (ESS), Functional Outcomes of Sleep Questionnaire (FOSQ), and Snore Outcomes Survey, also showed stable improvements through 36 months. Improvements in these scores exceeded the minimum clinically crucial differences of 2-3 points for ESS, 1.7-2.0 points for FOSQ, and 7.6 points for the Snore Outcomes Survey.
Comparison with Distal Hypoglossal Nerve Stimulation
The study also compared the efficacy of pHGNS to distal hypoglossal nerve stimulation (dHGNS), referencing results from the STAR trial. At 36 months, changes in AHI, oxygen desaturation index (ODI), and measures of sleepiness and quality of life were similar between the two approaches. Median AHI changes were -17.7 for pHGNS (THN3 trial) and -19.4 for dHGNS (STAR trial). ODI changes were -14.3 and -17.2, respectively.
Study Limitations
The researchers acknowledged some limitations, including the relatively small study population and the open-label nature of the long-term follow-up. Attrition, with a considerable number of participants not completing the full three-year follow-up, was also noted.
“Selective pHGNS is a safe, effective, well-tolerated treatment for moderate to severe OSA with a stable long-term profile,” the investigators concluded.
Disclosure: The study was sponsored by ImThera and LivaNova. Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. See the original publication for a complete list of author disclosures.
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