1. Field of the Invention
The present invention generally relates to treating sleep disorders, and more specifically relates to systems, devices and methods for treating sleep disorders such as obstructive sleep apnea.
2. Description of the Related Art
Obstructive sleep apnea (OSA) is caused by a blockage of the upper airway that occurs when the soft tissue in the throat collapses during sleep. During each OSA event, the brain briefly arouses the sleeping individual in order resume breathing. This type of sleep is extremely fragmented and of poor quality. When left untreated, OSA may result in various problems including sleepiness, high blood pressure, cardiovascular disease, weight gain, impotency, headaches, memory problems, job impairment, and motor vehicle crashes.
According to the National Institutes of Health, OSA is very common and affects more than twelve million Americans. Risk factors include being a male and being overweight. Another risk factor includes being over 40 years old; however, OSA can strike at any age. Despite the significant medical consequences of OSA, a lack of awareness by the public and healthcare professionals results in the vast majority of OSA sufferers remaining undiagnosed and untreated.
There have been a number of efforts directed to treating OSA. Perhaps the most widely-used treatment is referred to as continuous positive airway pressure (CPAP), whereby air under positive pressure is delivered into the upper airway through a specially designed nasal mask or pillow. When the patient inhales, the flow of high-pressure air keeps the airway open. CPAP is considered to be one of the most effective non-surgical treatments for alleviating OSA. However, CPAP patients complain about discomfort from the mask and hoses, bloating, nasal drying, and dry eyes. Thus, patient compliance is relatively poor (i.e. about 40% compliance).
U.S. Pat. Nos. 5,284,161 and 5,792,067 disclose devices for treating OSA that electrically stimulate the soft palate. These electrical stimulation devices have also had mixed results because of poor patient compliance, patient discomfort during sleep, and repeated arousal of the patient throughout the night.
In order to minimize the need for patient compliance, surgical methods for treating OSA have also been developed. One surgical method, referred to as uvulopalatopharyngoplasty, involves removing about 2 cm of the trailing edge of the soft palate to reduce the soft palate's ability to block the upper airway. Another procedure uses a surgical laser to create scar tissue on the surface of the soft palate. The scar tissue reduces the flexibility of the soft palate, which, in turn, reduces snoring and/or closing of the upper airway passage.
There are a number of problems associated with the above-described surgical procedures. First, the area subjected to surgical treatment (e.g. removal of palatal tissue or scarring of palatal tissue) may be larger than is necessary to treat the patient's condition. In addition, the surgical procedures are painful, and have extended and uncomfortable healing periods. For example, scar tissue on the soft palate may present a continuing irritant to the patient. Moreover, the procedures are not reversible in the event that they induce adverse side effects.
In response to the above problems, medical implants have been developed for treating OSA. For example, the PILLAR™ Palatal Implant System sold by Restore Medical of St. Paul, Minn. is an implantable device that uses several braided PET cylinders that are implanted in the soft palate. The PILLAR device has been associated with a number of adverse side effects, including extrusion, infection, and patient discomfort.
Another implant system sold under the trademark REPOSE™ by InfluENT of Concord, N.H., uses a bone screw that is inserted into the posterior aspect of the mandible at the floor of the mouth. A loop of suture is passed through the base of the tongue and attached to the titanium screw. The REPOSE™ system achieves a suspension or hammock of the base of the tongue, thereby making it less likely that the tongue base will fall back against the pharyngeal wall or soft palate during sleep. Due to the high activity of the tongue during wakefulness, the suture component of this device may cut into the tissue of the tongue (i.e. a “cheese-cutter” effect), causing device failure and requiring subsequent removal. Thus, the duration of beneficial effects afforded by the REPOSE™ implant may only be temporary.
Another implant system for treating OSA, trademark ADVANCE™, is being developed by Aspire Medical, Inc. of Sunnyvale, Calif. The system uses a bone anchor inserted into the mandible and a winged nitinol member implanted in the base of the tongue. Similar to the REPOSE™ system, the ASPIRE™ system may expose the tongue to a “hard stop,” i.e., the bone anchor does not move when the tongue moves, which may cause tearing of the tongue tissue (a “cheese-cutter” effect), loosening of the implant, and eventual device failure.
U.S. Pat. No. 7,367,340 assigned to Apneon, Inc. of Cupertino, Calif., discloses an implant that uses magnets for treating OSA. In one embodiment, a first set of magnets are implanted in the back of the tongue and a second set of magnets are implanted in a pharyngeal wall. The respective magnets in the tongue and the pharyngeal wall repel one another for opening the upper airway. Other embodiments involve placing a magnet in the tongue and then coupling this to a magnet placed external to the patient's neck and jaw. The efficacy of such a device is severely compromised by distances between the magnets, even more so in obese patients that may have excess adipose tissue in the inframandibular region.
The prior art tongue suspension systems described above are prone to failure as a result of the “hard-stop” effect that may cause tongue tissue to be incised, excess distances between the respective components, or the potential for components to become misaligned during use. The prior art magnetic implants described above have failed because the magnets are exposed to tissue in a manner that might compress tissue excessively, which may result in tissue damage. Moreover, magnetic implants become ineffective if the magnets migrate or flip. Thus, prior art implants have had limited success and may cause adverse health consequences for patients.
In view of the above results, there remains a need for systems, devices, and methods for safely and effectively treating OSA. There also remains a need for minimally invasive systems, devices, and methods for treating OSA. In addition, there remains a need for systems, devices, and methods for treating OSA that encourage patient compliance, minimize patient discomfort, and achieve long-term, efficacious results.