Differentiating varying degrees of central sensitization in chronic widespread pain using quantitative ultrasound

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Chronic widespread pain affects almost 11.4–24% of the general population. Central sensitization (CS) is thought to be the mechanism underlying chronic pain. The goal of this study was to determine whether ultrasound texture features (statistical measure of echointensity patterns) can differentiate chronic pain patients with varying degrees of CS, as our previous work has shown that texture features can differentiate patients with myofascial pain. Thirty patients with chronic widespread pain that fulfilled the 2016 fibromyalgia diagnostic criteria were included in the study. Patients completed the CS inventory, a questionnaire that indicates the degree of CS—mild, moderate, severe, and extreme. Patients’ upper trapezius muscle was then imaged using B-mode ultrasound. Ninety-one texture features were extracted from the acquired images, and a principal components analysis (PCA) was performed to reduce the features into components that accounted for a large proportion of the variability among the images. A MANOVA and post-hoc analyses were then performed on the features with the top three loading factors to determine whether they could differentiate patients with mild, moderate, severe, or extreme central sensitization. The PCA identified eight components that account for 95% of the variability among the images. The MANOVA and post-hoc analyses revealed that all extracted features could differentiate between two or more of the groups, and twelve variables could specify group membership ( Table 1 & a visual representation in Fig. 1 ). Texture feature analysis of the upper trapezius muscle can differentiate varying degrees of CS using a clinical classification system. Texture feature analysis of muscle should be further explored as a diagnostic marker of chronic widespread pain severity and development.