Myofunctional Therapy to Treat Obstructive Sleep Apnea: A Systematic Review and Meta-analysis
Several medical and surgical treatment modalities exist as treatment for obstructive sleep apnea (OSA).1–3 Four patho-physiological traits seen in patients with OSA are: the passive critical closing pressure of the upper airway (Pcrit), arousal threshold, loop gain, and muscle responsiveness (PALM) with categories of 1, 2, 2a, 2b, and 3.4 It has been demonstrated that patients in four of five PALM categories will benefit from anatomic interventions.4 Because the dilator muscles of the upper airway play a critical role in maintaining an open airway during sleep, researchers have explored exercises and other airway training (singing, didgeridoo, instrument playing) that target oral cavity and oropharyngeal structures as a method to treat OSA.5–7 Myofunctional therapy (MT) and proper tongue positioning in the oral cavity have been described since 1918 to improve mandibular growth, nasal breathing, and facial appearance.8Guimaraes has proposed MT as a treatment for OSA since the 1990s.9 MT is composed of isotonic and isometric exercises that target oral (lip, tongue) and oropharyngeal structures (soft palate, lateral pharyngeal wall).7,10 There have been an increasing number of studies evaluating the effect of MT in the form of case studies, case series, and most recently, two randomized controlled trials.7,10–13
The most comprehensive MT exercises are described by Guimaraes et al.7 and involve the soft palate, tongue, and facial muscles and address stomatognathic functions. For soft palate exercises, patients pronounce oral vowel sounds either continuously (isometric exercises) or intermittently (isotonic exercises).7Tongue exercises include moving the tongue along the superior and lateral surfaces of the teeth, positioning the tongue tip against the anterior aspect of the hard palate, pressing the entire tongue against the hard and soft palate, and forcing the tongue onto the floor of the mouth.7 Facial exercises address the lip (i.e., contraction and relaxation of the orbicularis oris), buccinators (i.e., suction movements and application of intraoral finger pressure against the buccinator muscles), and jaw muscles (i.e., lateral jaw movements).7 In addition, stomatognathic functions are addressed by instructing patients to inhale nasally and exhale orally without and then with balloon inflation, and performing specific swallowing and chewing exercises (i.e., swallowing with the teeth clenched together, tongue positioned in the palate and without contraction of perioral muscles; alternating chewing sides).7 A newer study describes a device that conditions and strengthens oral and tongue muscles.12
The objective of this study is to systematically review the literature for articles evaluating MT or oral/oropharyngeal exercises as treatment for OSA in both children and adults and to perform a meta-analysis on the available polysomnographic and sleepiness data.
Current literature demonstrates that myofunctional therapy decreases AHI by approximately 50% in adults and 62% in children. Lowest oxygen saturation, snoring, and sleepiness outcomes improve in adults. Myofunctional therapy could serve as an adjunct to other OSA treatments.