The Airway and Sleep Apnea
According to a recent study, electrical stimulation of the hypoglossal nerve can be an option for people with severe sleep apnea who no longer respond to continuous positive airway pressure (CPAP). Results of the study show that there are significant improvements in both subjective and objective sleep measures of obstructive sleep apnea (OSA). Scientists for this study used the Upper Airway Stimulation System of the Inspire Medical Systems.
Dr. Patrick J. Strollo, Jr., the medical director of Sleep Medical Center, University of Pittsburg School of Medicine in Pennsylvania, said that the overall results of their study were positive. He said that people with severe OSA who do not feel well with CPAP need another option, and electrically stimulating the hypoglossal nerve may be a good alternative. Dr. Strollo explained that when an electrode touches the hypoglossal nerve, the tongue becomes stimulated, causing the tongue to protrude and open up the air passageway. During the study they implanted a pacemaker, asked their subjects to sleep in their sleep laboratory, and adjusted the settings of the pacemaker to open up the airway during sleep.
Dr. Strollo’s study involved overweight (BMI of at least 28.4), middle-aged men with moderate to severe sleep apnea (apnea hypopnea index or AHI of at least 20 but not more than 50) who no longer respond to or tolerate CPAP. The participants underwent surgical consultation, endoscopy, and a polysomnographic study. There were a total of 126 participants who joined the study and were implanted with the Upper Airway Stimulation System.
After 12 months, results showed that the AHI was significantly reduced. The average AHI of the participants decreased to 29.3. There was also a 71% decrease in the oxygen desaturation index (ODI) of the patients; from 25.4 it fell down to 7.4. Moreover, the results of the Functional Outcomes of Sleep Questionnaire (FOSQ), and Epworth Sleepiness Scale (ESS) showed significant and great improvements before the Upper Airway Stimulation System were installed on the patients. The FOSQ scores of the patients rose from 14 to 17.2 after a year; while their ESS results normalized, from 11.6 to 7 (normal).
Dr. Strollo and his team also checked if there would be any withdrawal effects of the neurostimulator to the sleeping habits of the patients. The researchers randomly picked 46 participants and asked them to stop using the pacemaker for five days. After five days, the participants’ ODI and AHI increased, both returning to their baseline levels.
Implantation of the neurostimulator had a 1% incidence of serious events due to the system’s design, which was then corrected. Other non-serious events occurred also, such as 25% of the participants experienced transient pain, and 30% experienced tongue discomfort.
Medscape Medical News asked for the comment of Dr. Susan M. Harding, the medical director of the Sleep/Wake Disorders Center, University of Alabama, Birmingham, and she said that upper airway stimulation of the hypoglossal nerve is very promising; however, further studies must still be conducted. She iterated what Dr. Strollo had said that sleep apnea patients should have other treatment options aside from CPAP.
Dr. Strollo added that their study is currently being reviewed by the US Food and Drug Administration. To find out more about sleep apnea and its treatment, continue reading on SleepDisorders.com