Upper Airway Muscle Stiffness in Obstructive Sleep Apnea Assessed by Shear Wave Elastography

In obstructive sleep apnea (OSA), characterized by recurrent episodes of apnea and hypopnea, the activity of the upper airway dilator muscles is significant. In our study, we aimed to compare shear wave elastography (SWE) values of the genioglossus (GG), geniohyoid (GH), and mylohyoid (MH) muscles in patients with OSA.

In this prospective study, 90 adults who underwent full-night polysomnography were included. Participants were classified as non-OSA (apnea-hypopnea index [AHI] <5, n = 32) or OSA (AHI ≥5, n = 58), and OSA patients were further divided by severity. SWE was used to assess the stiffness of the bilateral GG, bilateral MH, and GH muscles.

Bilateral GG and GH stiffness values were significantly higher in OSA patients than in non-OSA individuals, whereas bilateral MH measurements did not differ between groups (P < .001, .006, and .004, respectively). Among OSA subgroups, left GG stiffness was significantly higher in severe OSA than in mild-moderate OSA (P = .043). Right GG stiffness showed positive correlations with AHI and supine AHI (r = 0.392 and r = 0.491, respectively; both P < .001). Left GG stiffness was positively correlated with AHI and rapid eye movement-AHI (r = 0.338, P = .001; r = 0.423, P < .001). GH stiffness was positively correlated with both AHI and oxygen desaturation index (r = 0.313, P = .003; r = 0.302, P = .004).

SWE may provide a useful non-invasive tool for evaluating upper airway muscle characteristics in OSA. Associations between upper airway muscle stiffness and polysomnographic parameters were observed; however, these cross-sectional findings should be considered exploratory and hypothesis-generating, requiring confirmation in larger studies.