Article

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 approximately 5MHz US transducer was used. Vibration
sonoelastography (VSE) was performed by color Doppler variance imaging while
simultaneously inducing vibrations (approximately 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+/-.11 cm(2). 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.

Langue : ANGLAIS