Assessment of myofascial trigger points (MTrPs): a new application of ultrasound imaging and vibration sonoelastography
PainSci commentary on Sikdar 2008: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.
Ultrasound elastography measures tissue stiffness by vibrating tissues with sound waves and measuring the differences — stiff tissue vibrates more slowly. If a trigger point is associated contracted muscle tissue, this method should show it.
In the first of a series of related studies, Sidkar et al. used USE on two healthy men and women with palpable trapezius trigger points that were not actively causing symptoms — “latent” trigger points. USE clearly showed areas of stiff tissue in the same location as palpable trigger points, but did not show the same thing in healthy tissue.
Three more studies by the same group have shown similar results since, studying more people in more detail: see , Sikdar 2009, Ballyns 2011, Turo 2013.
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
Myofascial trigger points (MTrPs) are palpable hyperirritable nodules in skeletal muscle that are associated with chronic musculoskeletal pain. The goal of this study was to image MTrPs in the upper trapezius muscle using 2D gray scale ultrasound (US) and vibration sonoelastography (VSE) for differentiating the soft tissue characteristics of MTrPs compared to surrounding muscle. MTrPs appeared as hypoechoeic elliptically-shaped focal regions within the trapezius muscle on 2D US. Audio-frequency vibrations (100-250 Hz) were induced in the trapezius muscle of four volunteers with clinically identifiable MTrPs, and the induced vibration amplitudes were imaged using the color Doppler variance mode, and were further quantified using spectral Doppler analysis. Spectral Doppler analysis showed that vibration amplitudes were 27% lower on average within the MTrP compared to surrounding tissue (p0.05). Color variance imaging consistently detected a focal region of reduced vibration amplitude, which correlated with the hypoechoeic region identified as an MTrP (r =0.76 for area). Real-time 2D US identifies MTrPs, and VSE is feasible for differentiating MTrPs from surrounding tissue. Preliminary findings show that MTrPs are hypoechoeic on 2D US and the relative stiffness of MTrPs can be quantified using VSE. Ultrasound offers a convenient, accessible and low-risk approach for identifying MTrPs and for evaluating clinical observations of palpable, painful nodules.
related content
- “Novel applications of ultrasound technology to visualize and characterize myofascial trigger points and surrounding soft tissue,” Sikdar et al, Archives of Physical Medicine & Rehabilitation, 2009.
- “Objective sonographic measures for characterizing myofascial trigger points associated with cervical pain,” Ballyns et al, J Ultrasound Med, 2011.
- “Ultrasonic characterization of the upper trapezius muscle in patients with chronic neck pain,” Turo et al, Ultrason Imaging, 2013.
- “Microscopic features and transient contraction of palpable bands in canine muscle,” Simons et al, Am J Phys Med, 1976.
- “Endplate potentials are common to midfiber myofacial trigger points,” Simons et al, Am J Phys Med Rehabil, 2002.
- “Accelerated muscle fatigability of latent myofascial trigger points in humans,” Ge et al, Pain Med, 2012.
- “Two-dimensional ultrasound and ultrasound elastography imaging of trigger points in women with myofascial pain syndrome treated by acupuncture and electroacupuncture: a double-blinded randomized controlled pilot study,” Müller et al, Ultrason Imaging, 2015.
- “Induction of muscle cramps by nociceptive stimulation of latent myofascial trigger points,” Ge et al, Exp Brain Res, 2008.
- “Uncovering the biochemical milieu of myofascial trigger points using in vivo microdialysis: an application of muscle pain concepts to myofascial pain syndrome,” Shah et al, Journal of Bodywork & Movement Therapies, 2008.
- “Ability of magnetic resonance elastography to assess taut bands,” Chen et al, Clin Biomech (Bristol, Avon), 2008.
- “Identification and quantification of myofascial taut bands with magnetic resonance elastography,” Chen et al, Archives of Physical Medicine & Rehabilitation, 2007.
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