Using a technique called magnetic resonance elastography, the Mayo Clinic researchers found that the myofascial muscle bands in a single patient with pain syndrome were 50% stiffer than surrounding muscle.
In a single control, who did not have the syndrome, there was no difference in tautness Jeffrey Basford, M.D., Ph.D., and colleagues reported in the December issue of Archives of Physical Medicine and Rehabilitation.
So far there has been no objective way to identify the myofascial pain syndrome condition and monitor treatment because there is an uncertain etiology and pathogenesis.
Patients with myofascial pain syndrome typically complain of pain in one anatomic region, such as the right side of the neck and shoulder, with tenderness being confined to that area.
The principal findings are localized bands of increased tone, known as taut bands, which contain even more circumscript points of tenderness, the investigators noted. When compressed, the bands produce stereotypical patterns of referred pain (trigger points).
"The findings of this study have significance in that they support the idea that [magnetic resonance elastography] imaging is capable of quantifying muscular pathophysiology whose existence was previously only apparent on physical examination," the authors concluded.
Several attempts to develop technology to characterize and quantify taut bands and trigger points have failed to win favor with clinicians because of shortcomings related to reliability. Magnetic resonance elastography, a recent advance in MRI imaging technology, may offer a more reliable means to identify and quantify tissue stiffness, the authors said.
Magnetic resonance elastography is performed with a 1.5-Tesla MRI machine. Shear waves are generated by means of a custom-built acoustically driven pneumatic transducer with gradient-echo image collection gated to the transducer's motion. In essence, the technology measures the elasticity of tissue in response to shear waves transmitted into the tissue.
Dr. Basford and colleagues initially evaluated magnetic resonance elastography in bovine gel phantoms representing muscles with taut bands. The investigators then used numeric modeling techniques to characterize shear wave propagation and establish a time increment.
As a final step in the preliminary evaluation of the technology, a patient with a three-year history of myofascial pain syndrome was evaluated, and findings were compared with those obtained from an individual without the pain syndrome. The taut band of the patient exhibited a stiffness of 9.0 KPa, compared with 6.2 KPa in surrounding musculature. The control individual had a stiffness value of 4.1 KPa.
The difference between the stiffness of the surrounding tissue in the patient and the stiffness value observed in the control individual "offers some support for the intuitively reasonable idea that even the resting tone of the uninvolved muscle of people with myofascial pain may be affected by this condition," the authors said.
|The authors had no disclosures. The study was supported by the National Institutes of Health.|
Zalman S. Agus, MD Emeritus Professor
University of Pennsylvania School of Medicine
Archives of Physical Medicine and RehabilitationSource Reference: Chen Q, et al "Identification and quantification of myofascial taut bands with magnetic resonance elastography" Arch Phys Med Rehab 2007; 88: 1658-1661.