Radiofrequency Energy Proves To Be Effective Against A Major Cause Of Obstructive Sleep Apnea

San Antonio, TX -- Obstructive sleep apnea syndrome (OSAS), (also known as sleep-disordered breathing) affects millions of Americans, has a significant impact on quality of life, and is the cause of significant costs in terms of decreased productivity in the work environment. Essentially, this condition is caused by collapse or narrowing of the airway during sleep resulting in a respiratory pause (cessation of air flow for less than ten seconds) or an apnea event (cessation of air flow greater than ten seconds). One of the major causes of OSAS is excessive tongue volume, which can lead to a nocturnally compromised airway.

A new study conducted by a team headed by Nelson Powell, MD, from Stanford University, set out to demonstrate the feasibility, safety, and possible efficacy of radiofrequency energy to reduce tongue volume in subjects with sleep disordered breathing. The findings of Dr. Powell's research will be presented before the 1998 American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) Annual Meeting and OTO Expo, which is being held September 13-16 at the Henry B. Gonzalez Convention Center in San Antonio, TX.

Methodology

Eighteen subjects, (17 men) 27 to 61 years of age were recruited for the study. All had, at a minimum, failed palatopharyngoplasty . All underwent a history and physical examination with a detailed airway evaluation with cephalometric radiographs and fiberoptic nasopharyngoscopy. This was to confirm that tongue base obstruction existed and that the palate region was clear or had been treated. Additionally:

Each patient underwent nocturnal polysomnography to document sleep parameters and SDB severity.

A cephalometric head film was taken prior to radiofrequency treatment to assess traditional airway measurements.

Airway scanning was done on a GE Sigma 1.5 Telsa MRI scanner. Scans of the upper airway from the dorsum of the tongue to the pediole of the epiglottis were taken on three separate occasions.

Quantitative evaluations were taken to measure speech and swallowing before and after treatments.

Questionnaires were administered to preclude research bias. Subject areas included quality of life, pain assessment, difficulty of speech, swallowing and taste.

Radiofrequency energy was delivered at 465kHz using an RF generator with a custom fabricated needle electrode and delivery device. A computerized energy algorithm controlled these parameters once safe ranges and limits were established. A protective thermal sheath was used on the proximal portion of the electrode to eliminate surface damage. The maximum temperature gradient was regulated at 80 degrees Celsius.

An area at the midline of the junction of the anterior two thirds of the tongue and the posterior base was selected for treatment. This specific region was selected because its sufficient distance from the hypoglossal and lingual nerves and yet close enough to the posterior tongue base to impact the posterior airway space. Two radiofrequency treatments were planned at each session. The treatments were spaced at a minimum of 3-4 week intervals.

Results

The 18 patients underwent 99 treatment sessions and 180 individual treatments with a mean of 1.82 treatments per session. MRI data, pre and post treatment, showed a reduction in tongue volume and increase in posterior airway space. The actual reduction was, overall, 17.1 percent with a maximum of 29 percent. The reduction was comparable to that achieved by surgical reduction techniques. This, along, with a reduction in apnea by the test subjects established the efficacy of the procedure.

The American Academy of Otolaryngology-Head and Neck Surgery Foundation Annual Meeting and OTO Expo is being held in San Antonio, TX, from September 13-16. More than 8,000 participants are expected for this gathering which includes scientific sessions, exhibits, posters, and a research program.