RESUMEN
PURPOSE: Shear-wave elastography (SWE) provides quantitative and absolute metrics for analyzing the elasticity of soft tissues. Despite the anterior scalene muscle (AS) is a key structure in patients with neck pain and nerve compressive syndromes, the majority of SWE studies only included asymptomatic subjects. This study aimed to analyze the Young's modulus and shear wave speed test-retest reliability in a sample of patients with neck pain symptoms to characterize the AS stiffness. METHODS: A diagnostic accuracy study acquiring a set of ultrasound images at C7 level in 42 patients with mechanical neck pain by one experienced examiner. After blinding the participants' identity, trial and side, the Young's modulus and shear wave velocity were measured by an independent experienced rater in randomized order. Intra-class correlation coefficients (ICC), standard error of measurement (SEM), minimal detectable changes (MDC) and coefficient of variation (CV%) were calculated. RESULTS: The sample reported moderate pain intensity (5.9/10 points) and disability (17.38/100 points). AS stiffness metrics assessed showed no significant differences between males and females, left and right side nor painful and non-painful side. (all, p > 0.05). Intra-examiner reliability was excellent for calculating the Young's modulus for shear wave speed (ICC > 0.90). CONCLUSION: The results support the use of this procedure for assessing the AS stiffness in populations with mechanical neck pain as excellent reliability estimates were obtained. However, future research should analyze case-control differences and the association between SWE metrics with clinical severity indicators.
