Abstract
Sikdar S, Shah JP, Gebreab T, Yen R-H, Gilliams E, Danoff J, Gerber LH. Novel applications
of ultrasound technology to visualize and characterize myofascial trigger points and
surrounding soft tissue.
Objective
To apply ultrasound (US) imaging techniques to better describe the characteristics
of myofascial trigger points (MTrPs) and the immediately adjacent soft tissue.
Design
Four sites in each patient were labeled based on physical examination as active myofascial
trigger points (A-MTrPs; spontaneously painful), latent myofascial trigger points
(L-MTrPs; nonpainful), or normal myofascial tissue. US examination was performed on
each subject by a team blinded to the physical findings. A 12∼5MHz US transducer was
used. Vibration sonoelastography (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 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 as follows: 0,
normal arterial flow in muscle; 1, elevated diastolic flow; 2, high-resistance flow
waveform with retrograde diastolic flow.
Setting
Biomedical research center.
Participants
Subjects (N=9) meeting Travell and Simons' criteria for MTrPs in a taut band in the
upper trapezius.
Interventions
Not applicable.
Main Outcome Measures
MTrPs were evaluated by (1) physical examination, (2) pressure algometry, and (3)
three types of US imaging including gray-scale (2-dimensional [2D] US), VSE, and Doppler.
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, with a size of .16±.11cm2. There were no significant differences in size between A-MTrPs and L-MTrPs. Sites
containing MTrPs were more likely to have a higher tissue imaging score compared with
normal myofascial tissue (P<.002). Small arteries (or enlarged arterioles) near A-MTrPs showed retrograde flow
in diastole, indicating a highly resistive vascular bed. A-MTrP sites were more likely
to have a higher blood flow score compared with L-MTrPs (P<.021).
Conclusions
Preliminary findings show that, under the conditions of this investigation, US imaging
techniques can be used to distinguish myofascial tissue containing MTrPs from normal
myofascial tissue (lacking trigger points). US enables visualization and some characterization
of MTrPs and adjacent soft tissue.
Key Words
List of Abbreviations:
A-MTrP (active myofascial trigger point), L-MTrP (latent myofascial trigger point), MPS (myofascial pain syndrome), MRE (magnetic resonance elastography), MTrP (myofascial trigger point), Po2 (partial pressure of oxygen), PPT (pain pressure threshold), RI (resistive index), 3D (3-dimensional), 2D (2-dimensional), US (ultrasound), VSE (vibration sonoelastography)To read this article in full you will need to make a payment
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Article info
Footnotes
Supported by the Intramural Research Program, National Institutes of Health (NIH), and the Clinical Center and Office of the Director, NIH.
No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.
Identification
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Published by Elsevier Inc.
