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Stanford Report, September 30, 1998

Sleep apnea eased with radiofrequency: 9/98

Sleep apnea eased with radiofrequency energy

New clinical results show that an outpatient procedure developed and tested at Stanford can alleviate obstructive sleep apnea by shrinking the base of the tongue.

The procedure, developed by surgeon Nelson Powell, MD, DDS, uses a wand-like instrument to deliver tissue-shrinking radiofrequency energy. The Food and Drug Administration approved the procedure last year as an effective treatment to reduce snoring. Now, Powell and his colleagues have gathered data showing that the same technology is equally effective in shrinking the tongue base ­ previously done only with surgery ­ to reduce obstructive sleep apnea.


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"This is the first new treatment for obstructive breathing disorders in 10 years," said Powell, a co-director of the Stanford Sleep Disorders Clinic and Research Center and clinical associate professor of psychiatry and behavioral sciences.

He reported the latest findings Sept. 11 at the annual meeting of the American Academy of Otolaryngology ­ Head and Neck Surgery Foundation, held in San Antonio.

Obstructive sleep apnea, also known as sleep-disordered breathing, is a serious condition affecting millions of Americans. It has a significant impact on quality of life and takes a major economic toll on workplace productivity.

Essentially, the condition results from collapse or narrowing of the airway during sleep, temporarily halting breathing. A major cause of this is excessive tongue volume.

Powell set out to demonstrate the feasibility, safety and possible efficacy of using radiofrequency energy to reduce tongue volume in people with sleep-disordered breathing. His co-authors, both from the Department of Psychiatry and Behavioral Sciences, were clinical associate professor Robert Riley, MD, DDS, and professor Christian Guilleminault, MD, associate director of the sleep center.

The researchers focused on 18 patients, 17 of whom were men. All had previously undergone surgery for apnea, and in each case the surgery had failed.

At the outset of the study, participants underwent a medical history and physical examination, including a detailed airway evaluation to confirm that a tongue base obstruction existed and that the palate region was clear or had been treated. In addition, patients spent a night in Stanford's sleep lab to allow the researchers to document their sleep parameters and the severity of their sleep-disordered breathing.

Anatomical airway measurements were assessed before treatment, and the team used magnetic resonance imaging to scan the upper airway on three separate occasions. Participants also had their speech and swallowing evaluated before and after treatment. In addition, the patients filled out questionnaires in which they assessed a number of factors, including quality of life, pain tolerance, difficulty of speech, swallowing and taste.

Treatment consisted of radiofrequency energy delivered at 465 kilohertz using a radiofrequency generator with a custom-fabricated needle electrode and delivery device. Once the researchers established safe dosage ranges and limits, a computerized energy algorithm controlled these parameters. A protective thermal sheath on the end of the electrode was used to eliminate surface damage. The maximum temperature gradient was regulated at 80 degrees C.

Powell performed the procedures on an outpatient basis. During each session, participants received two radiofrequency treatments. Sessions for individual patients were spaced at least three or four weeks apart.

At the conclusion of the study, the researchers compared before-and-after magnetic resonance images and found reductions in tongue volume and increases in upper airway space. The amount of reduction ­ averaging 17 percent in the study group, with a maximum of 29 percent ­ was comparable to that typically achieved through conventional surgical techniques. This, along with a significant reduction in apnea, established the efficacy of the procedure, Powell said.

In some patients, the difference was dramatic. Sleep monitoring showed, for instance, that one participant ­ a 35-year-old married man with four children ­ went from suffering 110 episodes of disrupted nighttime breathing per hour to just eight per hour, said Powell. "It changed his life," the surgeon said. SR