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Targeted hypoglossal nerve stimulation (THN) showed safety and efficacy for patients with moderate-to-severe obstructive sleep apnea (OSA), the randomized THN3 trial found.

Four months after receiving a THN device, patients who had had their devices activated at month 1 were more likely to meet criteria for treatment response in terms of reduced apnea-hypopnea index (AHI; 52.3% vs 19.6%) and improved oxygen desaturation index (ODI; 62.5% vs 41.3%) compared with controls who had not had their devices turned on yet.

"During the 4-month randomization period, THN therapy significantly improved measures of sleep-disordered breathing and patient-reported outcomes, including daytime somnolence and quality of life in treated vs control participants," reported Alan Schwartz, MD, of the Hospital of the University of Pennsylvania in Philadelphia, and coauthors in

After the 4-month mark, the controls had THN implants activated as well and joined the early-activation arm. In this combined treatment group, AHI and ODI response rates were 42.5% and 60.4%, respectively, at month 12/15, indicating some reduction in response -- and resulting in the long-term AHI response rate not meeting its prespecified efficacy endpoint.

Nevertheless, patients reported improvements in their Epworth Sleepiness Scale, Functional Outcomes of Sleep Questionnaire, and European Quality of Life 5-Dimension visual analog scale scores.

"Although AHI response rates appeared to decline during the period of longitudinal follow up, clinically important reductions in OSA burden were maintained, with comparable decreases in AHI and ODI after nearly a year of therapy in the entire group," the authors wrote. "Patient-reported outcomes further suggest that reductions in OSA severity, even without complete remission, can achieve clinically meaningful improvements in sleep quality and daytime function."

The trial tested the from ImThera Medical, which consists of an implanted pulse simulation device and a lead that transports the generated pulses to the hypoglossal nerve to activate their lingual muscles and to keep airways clear. Patients are given a remote that allows them to control the process of their nightly THN therapy.

As for safety, Schwartz's group reported two severe adverse events related to treatment: one case of neck pain as the result of lead tension and one instance of lead dislodgement. Furthermore, 6.5% of patients received replacements, explants, or revisions, and 72.5% experienced some form of adverse event ranging from perioperative wound events to stimulation discomfort.

These results come more than a decade after of the aura6000 system that supported THN as a viable treatment option for OSA, and nearly a decade after FDA approval of the Inspire upper airway stimulation device, another implanted nerve stimulation therapy for severe OSA, which has since seen from the original approval in adults.

While the similarities between the two systems are clear, THN may be more applicable to patients since the aura6000 THN trial had more broad parameters for inclusion than the long-standing that had tested the Inspire.

If THN makes it to market, it is still unlikely that it will replace the Inspire, which "has had 9 years to become the mainstay of hypoglossal nerve stimulation, with refinement in patient care resources, support for surgeons, and demonstration of long-term improvements in OSA-related outcomes," according to Ryan Jackson, MD, of the Washington University School of Medicine in St. Louis, Missouri, and Sebastian Jara, MD, MPH, of the University of Washington School of Medicine in Seattle.

"Nonetheless, if THN achieves FDA approval, it will provide a compelling additional surgical option for hypoglossal nerve stimulation with several advantages, including potentially elimination of the need for preoperative screening with [drug-induced sleep endoscopy] for insurance authorization. This will ease patient access to therapy, promote adoption of THN by surgeons, and thus provide welcome competition to spur further innovation in hypoglossal nerve stimulation," the duo noted in an .

THN3 was a trial testing proximal THN stimulation in positive airway pressure-intolerant patients with moderate to severe OSA. Data were collected from May 2015 to June 2018.

A total of 138 participants were included in the cohort (13.8% women, average age 56 years old, BMI 30). Median AHI was 36.5 events per hour and median ODI 35.1 per hour, indicating severe OSA at baseline.

Baseline characteristics were comparable between treatment and control arms except for more women and a slightly higher average AHI and greater time spent during sleep with oxygen saturation less than 90% in the treatment group.

The THN implant procedure took a median 77.5 minutes and 72% of patients were discharged on the same day.

Prespecified thresholds for THN response were a 50% or greater reduction in AHI to ≤20 per hour and an ODI decrease of 25% or greater.

Investigators reported that the treatment was not only successful, but fairly popular among participants. Over 80% said that they found using THN easy, that they were "satisfied or very satisfied with their outcome," that they would be willing to go through treatment again, and that they would recommend this form of treatment.

Among the limitations of the study, however, was that patients were not blinded to the treatment they received and that results may not be generalizable outside the studied patient population.

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