• Posted April 5, 2024

Nerve Zap Treatment for Sleep Apnea Less Effective in Obese People

Obese folks are less likely to benefit from a nerve-stimulation treatment for sleep apnea that's recently been made available to them, a new study reports.

The treatment is likely to be 75% less effective among obese people with BMIs of 32 to 35, compared to patients with lower BMIs, researchers found.

“Our study shows that the more overweight you are, the less likely it is that nerve-stimulation treatment will be effective in treating your sleep apnea,” said senior researcher Dr. Eric Landsness, an assistant professor of neurology with the Washington University School of Medicine in St. Louis.

“I'm not saying that we shouldn't put this device in patients with a BMI of 38 or 40,” Landsness added in a university news release. “But my job as a physician is to help overweight patients make an informed decision, to better understand their odds of success and realize that the chances of it working for them may be a lot less.”

The increasingly popular therapy, known as hypoglossal nerve stimulation, originally was approved in 2014 for sleep apnea patients whose weight was in the healthy range, researchers said in background notes.

But that approval has now been extended to patients with BMIs up to 40, which is considered severely obese. Healthy BMI ranges from 18.5 to 24.9, and 25 to 29.9 is considered overweight.

Sleep apnea occurs when the muscles in the mouth and throat relax while a person is asleep. Muscle slumping can partially or completely block the airways, especially in people with large tongues, thick necks and narrow airways.

These blockages cause people to stop breathing, which startles them awake to gasp for breath. The cycle repeats through the night, ruining good sleep and contributing to health problems like headaches, strokes, irregular heart rhythms and other heart-related ailments.

The treatment uses a small, battery-operated device implanted just above the ribs to deliver electrical jolts to the hypoglossal, the nerve that controls the tongue muscles responsible for keeping the upper airway open during sleep.

Each time the patient takes a breath, the device delivers an electrical impulse to the hypoglossal nerve, causing the tongue to move forward just enough to avoid an airway blockage that would choke off normal breathing, the researchers said explained.

This device offers a tempting alternative to a continuous positive airway pressure (CPAP) machine, currently the most common treatment for sleep apnea, researchers noted.

CPAP machines maintain open airways by forcing air through a breathing hose and a tightly fitting face mask.

The machines are effective, but they can be loud and uncomfortable, researchers said. About half of people who try a CPAP stop using it.

The FDA now allows hypoglossal nerve stimulation in heavier patients, and Medicare covers the device for patients with BMIs up to 35.

To see whether this therapy would work in overweight and obese patients, Landsness and colleagues recruited 78 people with BMIs up to 35 to receive the device between 2019 and 2023.

Overall, the device worked. Three out of four patients showed significant improvement in their sleep apnea, and most study participants experienced symptom reductions of at least 50%.

However, people with BMIs of 32 to 35 showed less improvement than patients with lower BMIs, results show.

The findings were published April 4 in the journal JAMA Otolaryngology-Head & Neck Surgery.

“Body mass index is clearly an important factor in predicting whether hypoglossal nerve stimulation will work for an individual patient,” Landsness said. “Our study shows an almost linear relationship between BMI and treatment success. For every unit of BMI increase over 32, the odds of successful treatment decrease by about 17%.”

The device is made by Inspire Medical Systems, and is the only FDA-approved hypoglossal nerve stimulator in the United States. About 50,000 patients worldwide have received the implant.

The device is implanted in a relatively simple outpatient procedure, researchers noted, but it can cost $50,000 to $100,000 out-of-pocket for people without insurance. The device can also take about a year to reach its full potential usefulness for a person.

“We have patients coming to us who really want this treatment, because they view it as a life-changing alternative to CPAP,” Landsness said. “It certainly can work for some people, but we don't want to recommend it to patients if there's a chance their BMIs will affect the device's usefulness.”

More information

Johns Hopkins Medicine has more about hypoglossal nerve stimulation for sleep apnea.

SOURCE: Washington University, news release, April 2, 2024