Ultrasound Shear Wave Elastography of the Sternocleidomastoid Muscle in Patients With Obstructive Sleep Apnea Syndrome

Abstract

Purpose The aim of this study was to evaluate the elasticity and stiffness of the sternocleidomastoid (SCM) muscle in patients with obstructive sleep apnea syndrome (OSAS) using ultrasound shear wave elastography (SWE), and to investigate the potential relationship between SCM muscle stiffness and the severity of OSAS. Methods This study included 72 patients with OSAS diagnosed by polysomnography (PSG) and 35 age- and sex-matched healthy controls who were admitted to the chest diseases outpatient clinic. Following the diagnosis, all participants underwent ultrasound shear wave elastography (SWE) to evaluate the elasticity and stiffness of the sternocleidomastoid (SCM) muscle. SWE measurements were performed in a standardized supine position, with care taken to ensure minimal muscle contraction during imaging. The mean shear wave velocity (SWV) values were recorded for both the right and left SCM muscles. The severity of OSAS was categorized based on apnea-hypopnea index (AHI) scores into mild, moderate, and severe groups. The SWE values were then statistically compared between OSAS subgroups and healthy controls. Correlation analyses were also performed between SCM stiffness (SWV) and AHI values to assess the relationship between muscle stiffness and disease severity. Results A total of 107 individuals were included in the study: 72 patients with OSAS and 35 healthy controls. The OSAS group showed significantly higher BMI, body fat ratio, neck circumference, and sternocleidomastoid (SCM) muscle stiffness values compared to controls (p < 0.01). Shear wave elastography revealed a significant increase in SCM stiffness with advancing OSAS severity. Spearman's correlation analysis showed that right and left SCM stiffness values were also positively correlated with OSAS severity (r = 0.164 and r = 0.241, respectively; p < 0.001). Conclusion Ultrasound shear wave elastography revealed increased SCM muscle stiffness in OSAS patients, correlating with disease severity. These findings suggest that SCM muscle biomechanical properties may serve as a supplementary marker in evaluating and monitoring OSAS progression.