Novel Applications of Ultrasound Technology to Visualize and Characterize Myofascial Trigger Points and Surrounding Soft Tissue

Abstract

Objective-Apply ultrasound (US) imaging techniques to better describe the characteristics of myofascial trigger points (MTrPs) and the immediately adjacent soft tissue.Design-Descriptive (exploratory) study. Setting-Biomedical research center.Participants-9 subjects meeting Travell and Simons's criteria for MTrPs in a taut band in the upper trapezius. Interventions-(None)Main Outcome Measures-MTrPs were evaluated by 1) physical examination, 2) pressure algometry, and 3) three types of ultrasound imaging including grayscale (2D US), vibration sonoelastography (VSE), and Doppler.Methods-Four sites in each patient were labeled based on physical examination as either active MTrP (spontaneously-painful, A-MTrP), latent MTrP (non-painful, L-MTrP), or normal myofascial tissue. US examination was performed on each subject by a team blinded to the physical findings. A 12-5 MHz US transducer was used. VSE was performed by color Doppler variance imaging while simultaneously inducing vibrations (~92Hz) with a handheld massage vibrator. Each site was assigned a tissue imaging score (TIS) as follows: 0 = uniform echogenicity and stiffness; 1 = focal hypoechoic region with stiff nodule; 2 = multiple hypoechoic regions with stiff nodules. Blood flow in the neighborhood of MTrPs was assessed using Doppler imaging. Each site was assigned a blood flow waveform score (BFS) as follows: 0 = normal arterial flow in muscle; 1 = elevated diastolic flow; 2 = high-resistance flow waveform with retrograde diastolic flow.Results-MTrPs appeared as focal, hypoechoic regions on 2D US, indicating local changes in tissue echogenicity, and as focal regions of reduced vibration amplitude on VSE, indicating a localized stiff nodule. MTrPs were elliptical in shape, with a size of 0.16 ± 0.11 cm 2 . There were no significant differences in size between A-MTrPs and L-MTrPs. Sites containing MTrPs were more likely to have higher TIS compared to normal myofascial tissue (p<0.002). Small arteries (or enlarged

Ultrasound Imaging and Muscle Function

“…22,23 As a decrease in muscle size has been linked to various pathologies and impairments, 16,19 the use of the technology has continued to expand to include investigation of muscles such as the supraspinatus and infraspinatus, 35 rectus femoris, 13 biceps brachii, 2 transversus abdominis (TrA) and internal oblique (IO), 20 rectus abdominis, 8 cervical multifidus, 45 trapezius, 56 rectus femoris, sartorius, and iliopsoas. 53 Other aspects of muscle morphology and function that have been explored with USI include composition, 44,61,66 changes in internal architecture (pennation angles), 48,80 force generation, 13 and muscle activity (ie, electrical activity recorded by electromyography [EMG]). 6,28,34,36,52 While physical therapists are familiar with therapeutic ultrasound and the underlying physics, they often lack training regarding the principles and instrumentation underlying USI.…”

“…The first is information about the echogenicity or reflective properties of a tissue, which is an indicator of its composition or makeup (eg, how much collagen or fluid it contains), and the second is information about the architecture (eg, internal structure, size, and shape) or position of a structure. Recent examples of how researchers have used information about the echogenicity of muscle and the perimuscular tissue obtained with conventional USI to comment on the composition of these structures include an investigation by Strobel et al in 2005 66 that employed USI to detect fatty atrophy of the supraspinatus and infraspinatus, an exploration to detect muscle trigger points in the upper trapezius muscle by Sikdar and colleagues in 2009, 61 and an examination of the perimuscular tissue of the lumbar spine in persons with low back pain (LBP) by Langevin et al in…”

Effect of Latent Myofascial Trigger Points on Strength Measurements of the Upper Trapezius: A Case-Controlled Trial

“…This study's results could have been more emphatic if we had used a study design involving a pretest-posttest comparison after a trigger-point release or if we had carried out a two-group study in which the experimental group received treatment to alleviate the trigger point. Ensuring the complete return of muscle to its normal state by ascertaining the complete mitigation of the trigger point using advanced techniques such as thermography 15 and ultrasound 16 would also have strengthened our results.…”

The Use of Photomedicine in Musculoskeletal Pain

“…More recently, detection of biochemicals related to pain and inflammation in MTrP site [25], the sonographic methods of MTrPs [26] and the magnetic resonance elastography for taut band image [27] are potential objective outcome assessment tools in the MTrPs diagnosis.…”