Posted by sleepsurgeon on October 22, 2009 at 08:26:16:Many patients have asked about the current research on sleep apnea surgery. Over the past few years, a tremendous amount of effort and funding have been committed to develop new surgical treatment for sleep apnea. I have either been, or currently am an advisor, or have had discussion with these medical device companies. I will summarize the research activity.
There are two major pathways. One is to develop airway implants to limit the collapsibility of the airway and the second is to simulate the nerve of the tongue (hypoglossal nerve) to increase the muscular tone and limit collapse.
Apneon Medical Inc. studied the use of magnets. By implanting magnets with the same polarity facing one another in the airway (tongue and lateral wall), the magnets repel one another, thus limit the collapse of the soft tissues. Although the concept was interesting, it was a failure because extrusion of the magnet was a problem, magnets are not MRI compatible and the repelling forces of the magnets can not be controlled.
Aspire Medical Inc. studied the use of adjustable tongue implants to support the tongue. The implant is first inserted into the tongue and after a few weeks of healing, a second procedure (under local anesthesia) is done to “tighten” the tongue implant and pull the tongue base forward. The company had two clinical trials in Europe and the results showed approximately 50% reduction of the RDI. Although the results are acceptable, there were implant breakage and project was discontinued.
Pavad Medical Inc. studied palatal and tongue implants that can be activated during sleep to support the soft tissue. The advantage of Pavad over Aspire is that it does not require a second procedure and the “titration” can be done multiple times after surgery to improve the support of the soft tissues. The company is planning for trial in Europe.
There are three hypoglossal nerve stimulation companies, Inspire Medical, Imthera Medical and Apnex Medical. Both Inspire Medical and Apnex Medical use a nerve stimulator (implanted in the chest wall with tunneling to the neck where the hypoglossal nerve is located) linked to a lead in the trachea. The tongue is stimulated during inspiration, thus prevent the collapse of the tongue. Imthera Medical does not believe in linking its stimulator to respiration and simply applies a baseline stimulation of the tongue to improve the muscular tone. Inspire Medical has completed European trial and is planning for US trial.
Based on the old data from Metronics Medical’s hypoglossal stimulation project in the early 1990s, there was significant improvement of patients with severe sleep apnea. However, the problem was malfunctioning of the stimulator and the surgical procedure is fairly invasive since it involves a neck procedure to locate the nerve, a chest wall procedure to place the stimulator with tunneling to connect with the neck. Additionally, a lead placement into the trachea is needed as well. In comparison with the MMA results, hypoglossal nerve stimulation is probably going to be similar.
I do believe that if successful, tongue implant surgery can be done in conjunction with UPPP to improve the outcomes and but I am doubtful that the results will be as good as MMA. However, the improvement may be sufficient for some patients to elect not to have more surgery. It can also provide additional improvement for patients with residual issues following MMA. The hypoglossal stimulator results may be as good as MMA. What is not known is the invasiveness of the procedure as compared to MMA, the multiple sites of operation (3) as well as the reliability of the stimulator.
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