Megan Brooks

June 06, 2013

BALTIMORE, Maryland — Electrical stimulation of the hypoglossal nerve is a promising treatment for moderate to severe obstructive sleep apnea (OSA) in patients who do not respond to or can't tolerate continuous positive airway pressure (CPAP) therapy, according to results a phase 3 multicenter study.

The study found clinically and statistically significant improvement in objective and subjective sleep measures of OSA severity in patients implanted with the Upper Airway Stimulation System from Inspire Medical Systems, which sponsored the trial.

"Overall the results were very positive," Patrick J. Strollo Jr, MD, medical director of the Sleep Medicine Center, University of Pittsburgh School of Medicine in Pennsylvania, told Medscape Medical News. Patients with moderate to severe OSA in whom CPAP fails "need an alternative treatment," and hypoglossal nerve stimulation may provide "a therapeutic option," he said.

"When an electrode is placed in the hypoglossal nerve the tongue is stimulated to actually protrude and that in essence offsets upper airway closure during sleep," Dr. Strollo explained. "The implantation takes place, and the patient is subsequently brought into the sleep laboratory where the pacemaker is adjusted to the appropriate setting to allow airway opening during sleep."

Dr. Strollo presented the phase 3 data as a late-breaking abstract here June 5 at SLEEP 2013: Associated Professional Sleep Societies 27th Annual Meeting.

A Pacemaker for OSA?

The study enrolled primarily male middle-aged overweight adults (mean body mass index, 28.4 kg/m < sup > 2 < /sup > ) with moderate to severe OSA (apnea hypopnea index [AHI] > 20 and < 50) who had not responded to or had not tolerated CPAP. All eligible participants underwent a screening polysomnographic study, surgical consultation, and drug-induced sleep endoscopy. A total of 126 patients without complete concentric collapse at the retropalatal airway were implanted with the Upper Airway Stimulation System.

At 12 months, AHI was reduced significantly, from a median of 29.3 at baseline to 9.0, "which is in the mild category," Dr. Strollo said. The oxygen desaturation index (ODI) fell from 25.4 to 7.4. "So there was a 68% reduction in the AHI and a 71% reduction in the ODI at 12 months," he noted.

The Epworth Sleepiness Scale (ESS) and the Functional Outcomes of Sleep Questionnaire (FOSQ) also showed significant improvement from before implantation to 12 months. ESS scores were 11.6 at baseline and fell to 7.0 (normal) at 12 months. The FOSQ scores rose from 14 at baseline to 17.2 at 12 months.

The researchers also looked at the withdrawal effect of the neurostimulator by randomly assigning 46 responders to withdrawal of therapy for at least 5 days or continued maintenance therapy. "In the maintenance group there were no changes in measures of sleep-disordered breathing, and in the withdrawal group after 5 days of turning off the pacemaker the AHI and ODI basically came back up to baseline levels," Dr. Strollo said.

There was a 1% incidence of serious adverse events related to the implantation that necessitated a device revision. The 2 main nonserious adverse events were transient pain (25% of patients) and some tongue discomfort (30%) that was associated with the stimulation, was self-limited, and improved over time.

The data from this phase 3 study are now under review at the US Food and Drug Administration, Dr. Strollo said.

"Big First Step"

Reached for comment, Susan M. Harding, MD, medical director of the Sleep/Wake Disorders Center, University of Alabama, Birmingham, told Medscape Medical News that upper airway stimulation is a "potentially promising treatment for patients who cannot tolerate CPAP." However, there is "much research which needs to be done about selecting which patients will best respond to this treatment," she said.

The results of this phase 3 study are a "big first step in accessing the safety and efficacy of upper airway stimulation," Dr. Harding said. The fact that the investigators looked at long-term outcomes at 12 months is a strength of the study, she said.

Current options for patients in whom CPAP fails include oral appliance therapy and maxillary mandibular advancement (MMA) surgery. "Oral appliance therapy does not have surgical risks and is a wonderful option for some patients," Dr. Harding said. "The [neurostimulator] implantation procedure is less invasive than MMA surgery, and selected patients may prefer this treatment," she noted.

Echoing Dr. Strollo, Dr. Harding said, "There is a need for more options or even replacement therapies for CPAP in our patients with obstructive sleep apnea. Untreated sleep apnea is associated with poor health outcomes and excessive sleepiness, and treatment improves many of these outcomes."

Dr. Strollo receives research support from Inspire Medical Systems, which funded the study. Dr. Harding has disclosed no relevant financial relationships.

SLEEP 2013: Associated Professional Sleep Societies 27th Annual Meeting. Abstract LBA 6. Presented June 5, 2013.


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