New Application may be the First To Validate
and Identify MTP's (TrP's) of Chronic Myofascial Pain.
A New Application of
2-Dimensional Gray Scale Ultrasound and Vibration
Sonoelastography to Image Myofascial Trigger Points in the Upper Trapezius
Muscle. Jay P. Shah, MD (NIH- CC, Bethesda, MD); Tadesse M. Gebreab, BS;
Lynn H. Gerber, MD; Elizabeth A. Gilliams, BA; Siddhartha Sikdar, PhD.
Disclosure: T.M. Gebreab, none; L.H. Gerber, none; E.A. Gilliams, none; J.P.
Shah, none; S. Sikdar, none.
Objective: To qualitatively describe and quantify the size, shape, and
tissue characteristics of myofascial trigger points (MTrPs). Design: A
descriptive preliminary study. Setting: Biomedical research hospital.
Participants: 4 healthy subjects with latent MTrPs identified in the upper
trapezius, according to Travell and Simons's criteria. Interventions:
Scanning MTrPs in the upper trapezius using a Philips IU22 ultrasound (US)
machine and a LI2-5 transducer; real-time imaging at rest, during isometric
contraction and during active stretching of the upper trapezius muscle,
while simultaneously inducing audio frequency vibrations (150-250Hz) in the
muscle. Main Outcome Measures: The tissue characteristics of MTrPs compared
to surrounding muscle were investigated in terms of echogenicity (using
2-dimensional [2D] US) and stiffness (using vibration sonoelastography,
VSE). VSE is based on the principle that a vibration stimulus causes a
localized region of stiffer tissue to vibrate with a lower amplitude
compared to the surrounding less stiff tissue. VSE was performed using 2
methods: the induced vibration amplitudes in the trapezius were imaged using
the color Doppler variance mode, and were further quantified using spectral
Doppler analysis. Results: MTrPs appeared as hypoechoic elliptically-shaped
focal regions within the trapezius muscle on 2D US. Spectral Doppler
analysis showed that vibration amplitudes were 27% lower on average within
the MTrP compared to surrounding tissue (P<.05). Color variance imaging
consistently detected a focal region of reduced vibration amplitude, which
correlated with the hypoechoic region identified as an MTrP (r=,76 for
area). During muscle contraction and muscle stretch, these focal regions
deformed in shape and could be tracked with real-time 2D US and color
variance imaging. Conclusions: Real-time 2D US and VSE are novel imaging
methods for differentiating MTrPs from surrounding tissue. Preliminary
findings show that MTrPs are hypoechoic on 2D US and the stiffness of MTrPs
can be quantified using VSE. The palpable nodule is deformable with muscle
contraction and stretch. US technology offers a convenient, accessible and
low-risk approach for evaluating clinical observations of stiff, palpable
nodules. Key Words: Trigger points, myofascial; Rehabilitation.
Special thanks to Devin