Assessment of Myofascial Trigger Points via Imaging

Abstract

This study systematically reviewed the published literature on the objective characterization of myofascial pain syndrome and myofascial trigger points using imaging methods. PubMed, Embase, Ovid, and the Cochrane Library databases were used, whereas citation searching was conducted in Scopus. Citations were restricted to those published in English and in peer-reviewed journals between 2000 and 2021. Of 1762 abstracts screened, 69 articles underwent full-text review, and 33 were included. Imaging data assessing myofascial trigger points or myofascial pain syndrome were extracted, and important qualitative and quantitative information on general study methodologies, study populations, sample sizes, and myofascial trigger point/myofascial pain syndrome evaluation were tabulated. Methodological quality of eligible studies was assessed based on the Quality Assessment of Diagnostic Accuracy Studies criteria. Biomechanical properties and blood flow of active and latent myofascial trigger points assessed via imaging were found to be quantifiably distinct from those of healthy tissue. Although these studies show promise, more studies are needed. Future studies should focus on assessing diagnostic test accuracy and testing the reproducibility of results to establish the best performing methods. Increasing methodological consistency would further motivate implementing imaging methods in larger clinical studies. Considering the evidence on efficacy, cost, ease of use and time constraints, ultrasound-based methods are currently the imaging modalities of choice for myofascial pain syndrome/myofascial trigger point assessment.

Contracture Knots vs. Trigger Points. Comment on Ball et al. Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response. Diagnostics 2022, 12, 321

“…Yet, Ball et al contrasted Sikdar et al’s findings with “previous US studies” that “had instead identified and labeled TrPs as hypoechoic”. The two cited papers were neither published previously, nor contradicted Sikdar et al’s 2010 publication [ 18 ]. Mazza et al’s systematic review was published in 2021, and accurately quoted Sikdar et al’s findings [ 18 ] as did Duarte et al (2021), who never mentioned hypoechoic areas other than when referencing Sikdar et al [ 19 ].…”

Ultrasound Confirmation of the Multiple Loci Hypothesis of the Myofascial Trigger Point and the Diagnostic Importance of Specificity in the Elicitation of the Local Twitch Response

“…The visual confirmation of contracture knots in the muscle being hyperperfused challenges the idea that the therapeutic benefit of dry needling is related to a “wash out effect” that somehow results in reperfusion of what we now suggest is an already hyperperfused region [ 20 , 21 ]. We propose a new hypothesis suggesting that when performing TrP-DN, an initial therapeutic effect may occur due to decreasing (not increasing) perfusion of hyperperfused contracture knot relative to the surrounding skeletal muscle.…”

“…Proper understanding of ultrasound imaging (US) suggests that, in general, hyperperfused structures appear as hypoechoic (dark grey) and hypoperfused structures as hyperechoic (light grey) [ 19 ]. Previous US studies had instead identified and labeled TrPs as hypoechoic (dark grey) [ 20 , 21 ]. A hypoechoic TrP image suggests either anisotropy (image error) or, in direct contrast to widely accepted micro-dialysis literature [ 17 , 18 ], that the TrP is a hyperperfusion area.…”

Efficacy of Dry Needling Under EMG Guidance for Myofascial Neck and Shoulder Pain: A Randomized Clinical Trial

“…16 The diagnosis of MTrPs has always been a difficult problem; the main methods for detecting MTrPs are as follows: thumb palpation, tenderness threshold detected by pain detector, ultrasound imaging, electromyography (EMG), magnetic resonance elastography and infrared thermography. 17 Needle EMG studies have found that abnormal SEA in MTrPs 18,19 and DN treatment could effectively reduce SEA at MTrPs, 20,21 while DN at the exact MTrPs seems more effective than needling at non-MTrPs. 22 The use of EMG could help find MTrPs more accurately and observe the inactivation status of MTrPs in real time.…”