| Myofascial pain syndrome (MPS) is a common, nonarticular musculoskeletal disorder, characterized by myofascial trigger points (MTrPs). The clinical detection of MTrPs has poor inter-rater reliability. Ultrasound imaging could provide reliable and objective information. Therefore, the overall purpose was to assess the attributes of ultrasound of the trapezius muscle in patients with MPS and potential discriminative ability. Quantitative B-mode ultrasound characteristics for the healthy trapezius muscle using blob area, count and mean echo intensity (EI) was demonstrated to provide differences between healthy and patients with regional neck pain. 98.55% of the overall variance was explained by the median blob area, mean blob count and mean EI. These results provide robust discriminative ability using these measures between clinically apparent regional neck pain and healthy muscle. Subsequently, texture analysis was used to evaluate the upper trapezius muscles of healthy volunteers, and patients who fulfilled the clinical criteria of latent MTrP and active MTrP. Principal component analysis (PCA) demonstrated twelve components accounting for 92.8% of the cumulative variance. Some texture features with highest loading included: energy 45 and 135 degrees (co-occurrence direction), maximum probability 90 degrees, cluster shade 0 and 45 degrees, cluster prominence 0 degrees, dissimilarity average, difference entropy average, inverse difference, information measure 1 90 degrees, correlation 45 and 90 degrees, information measure 2 average. Based on multivariate analysis of variance (MANOVA), significant between group differences (P< 0.001) suggesting texture analyses provides an objective, robust method to discriminate between these clinical groups. This technique was not dependent upon a visually apparent hypoechoic region within the muscle. This is a fascinating discovery since it suggests that the entire muscle in a patient who has MPS could be affected. Further research examining the incorporation of texture analytic techniques into diagnostic criteria of MPS and their effects upon clinical care are recommended. |
