Genioglossus Muscle Training for Snoring and Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common disorder characterized by intermittent narrowing or closure of the upper airway during sleep. Loss of muscle tone with sleep onset and decreases in ventilatory drive following the loss of the wakefulness stimuli to breathe combine to result in upper airway closure in patients with structurally susceptible upper airways. The genioglossus (GG, tongue) muscle plays an important role in maintaining upper airway patency. The GG is responsible for tongue protrusion and stiffens the tongue and prevents posterior tongue displacement and upper airway closure. The GG is a phasic respiratory muscle. One can demonstrate inspiratory bursts in GG EMG activity slightly preceding the onset of inspiratory activity of respiratory pump muscles. The inspiratory bursts of GG activity also increase in response to negative pressure in the upper airway to help maintain upper airway patency. In some OSA patients this response is blunted. While one study did not find a difference in protrusion muscle strength between a group of OSA patients (apnea hypopnea index, AHI = 20/hour) and normal controls (Mortimore et al) there was wide variability in muscle strength at similar AHI values. Another study (Oh et al) did find a correlation between tongue protrusion strength and the apnea index (lower strength, higher apnea index). It is hypothesized that strength training of the GG will reduce snoring and sleep apneas by augmenting the resting GG tone and enhancing the ability of the muscle to respond to negative upper airway pressure. Training of upper airway muscles including the tongue is often used in rehabilitation of patients with prior cerebrovascular accidents or damage due to surgical resection for cancer. Typically, the patient presses the tongue against the back of the upper teeth (direction both upward and forward). However, it is believed that tongue protrusion is best trained by active forward protrusion of the tongue between the teeth under load. To facilitate GGs training participants will push a spring loaded piston forward with the tongue. The piston fits inside an outer chamber. The piston can also be connected to a force measuring device to estimate protrusive tongue force.

Two groups of participants will be examined: Group 1: primary snoring and Group 2: mild to moderate OSA patients (apnea-hypopnea index < 30/hour) who are not severely obese (BMI < 40 Kg/M2) and do not have significant structural abnormalities of the upper airway or muscle dysfunction. This preliminary investigation consists of a randomized controlled trial (training versus sham training) with two months of daily training (5 out of 7 days each week). A home sleep study (including EEG) will be performed before and following the training. The change in the apnea-hypopnea index adjusted for sleep stage and body position will be compared. Use of home sleep studies will dramatically reduce the cost of the study. A sleep technologist will educate subjects on performance of training maneuvers and meet with them weekly to observe the subject's technique and measure tongue strength. A training log will be kept by the subjects using training schedule sheets and training will be directly monitored at least 2 times weekly through with a study clinician (electronically via facetime, skype or by direct observation).