Myotonometry demonstrates changes of lingual musculature in obstructive sleep apnoea

Upper airway dilator muscles are important in the pathogenesis of obstructive sleep apnoea (OSA). Previously, soft palate and tongue muscles of patients with OSA have been studied from a histological point of view. Electromyographic studies revealed increased activity of upper airway dilator muscles. We used computerized endopharyngeal myotonometry (CEM) to measure the biomechanical properties of lingual musculature, mainly the genioglossal muscle, to characterize changes of tongue muscles in patients with OSAS. The method records and analyzes the response of the tongue sublingually after a brief mechanical impact. It enabled us to evaluate the most important parameters of tissue tone--stiffness, which is expressed as a frequency, and elasticity, as a logarithmic decrement of the damped oscillation. The results of CEM indicated that patients with OSAS show an increased stiffness (14.1 +/- 0.7 Hz) of the tongue in comparison with non-snoring subjects (11.5 +/- 0.2 Hz). The elasticity of the tongue is decreased, which is numerically expressed as an increased decrement (4.0 +/- 0.2) in patients with OSA in comparison with non-snorers (2.2 +/- 0.2). Changes in the biomechanical characteristics of lingual musculature during wakefulness could result from pathophysiological processes caused by obstructive sleep apnoea.