Asians with sleep apnoea fare well with hypoglossal nerve stimulation

Hypoglossal nerve stimulation is safe and effective for reducing apnoea-hypopnoea index (AHI) in Asian patients with obstructive sleep apnoea (OSA), according to early experience from a single tertiary Singaporean sleep centre.

Six months after implantation of the hypoglossal nerve stimulation device, the mean apnoea-hypopnoea index (AHI) decreased from 33.6 events/h at baseline to 7.1 events/h. All patients (100 percent) achieved surgical success, defined as at least a 50-percent reduction in AHI from baseline and a postoperative AHI of <20 events per h. [Ann Acad Med Singap 2025;54:316-318]

However, the patients reported no significant improvements in daytime sleepiness and its impact on activities of daily living. Mean Epworth Sleepiness Scale score remained unchanged at 7.5 (p=0.535), while the mean Functional Outcomes of Sleep Questionnaire score decreased from 29.6 at baseline to only 27.93 at 6 months (p=0.309).

When analysis was stratified by skeletal class in a subset of patients, all sleep parameters and outcomes were consistent between patients with skeletal class II and those with class I or III.

As for safety, most implant surgeries (87 percent) were completed without incidence. One patient had transient hypoglossal neuropraxia, and another had transient marginal mandibular neuropraxia.

The analysis included 15 patients (mean age 53.7 years, 88.7 percent male, 80 percent Chinese). The mean BMI was 25.2 kg/m², and the mean neck circumference was 38.7 cm.

“This study represents the first report of the outcomes of hypoglossal nerve stimulation in an Asian population. For the same severity of OSA, Caucasian patients are known to have higher BMIs and less skeletal restriction than Asians. Our cohort displayed these characteristic differences, with a lower mean BMI and higher mean AHI compared with Caucasian-predominant registries,” the authors said. [Laryngoscope 2020;130:1333-1338; Sleep 2010;33:1075-1080]

“Our hypothesis was that skeletal restriction may limit room for tongue protrusion, which could conceivably limit the effectiveness of hypoglossal nerve stimulation. As our initial case series was small, the sample size was likely insufficiently powered to compare AHI reductions between skeletal classes,” they added.

Aside from the small sample size, the authors acknowledged that the use of postoperative titration polysomnography to measure the postoperative AHI may not fully reflect AHI for the entire night. They shared that they would update their analysis with a larger sample size in the future.

“As hypoglossal nerve stimulation becomes more widely adopted in Asian sleep centres where skeletal restriction is prevalent, future research should focus on whether these anatomical differences warrant adjustments to treatment protocols or eligibility criteria. Addressing these gaps is critical to delivering equitable care and optimizing outcomes across ethnicities,” they said.