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10 Articles in Volume 8, Issue #6
CES for Mild Traumatic Brain Injury
Duloxetine: A New Indication for the Treatment of Fibromyalgia
Evaluating Pain Intervention Effectiveness and Compliance
Low-level Laser Therapy for Trigeminal Neuralgia
Neurobiological Basis for Chronic Pain
Orbital-Inner Canthus Headache due to Medial Temporal Tendonitis
Pain Care for a Global Community: Part 1
Unraveling the Mysteries of Myofascial Pain Syndromes
Vitamin D for Chronic Pain
‘Head to Toe’ Nonprescription Drug History

Unraveling the Mysteries of Myofascial Pain Syndromes

The results of recent studies tend to suggest that Magnetic Resonance Elastrography (MRE) technology can detect and quantify deep taut bands of soft tissue and accurately distinguish a symptomatic or pathologic taut band vs a more normal region of tightness.

There are few syndromes in musculoskeletal medicine that elicit more controversy and debate than what some authors have termed “functional syndromes” or myofascial pain syndromes (MPS) perhaps because little is known, understood, or agreed upon regarding these conditions. As recently as 2008, an article appeared in a prestigious journal which summarized the available literature on the reliability of manual palpation in the detection of myofascial trigger points ( a key feature of MPS) and concluded that existing methods of identifying TPs is generally poor and, as such, clinicians are urged toward “simpler and more global assessments of patient status.”1 It is not unusual to find this type of report in the literature which helps explain the difference in opinion within the clinical community in regards to the existence of entities such as trigger points.

To date, there are no gold standard imaging or electrophysiologic tests, or even clear universally accepted diagnostic criteria, for many of these syndromes. Without clear diagnostic criteria, practitioners are left with treating a cluster of symptoms guided primarily by patient symptoms or self-report. In the absence of a clear pathology, patient complaints of pain can be attributed by the treating physician as motivated by “other” factors such as: drug seeking behavior, malingering, or simply anxiety-mediated neurosis having no somatic origin.

Conditions such as fibromyalgia, poly-arthralgia, and myofascial dysfunction are at the top of the list of these mystery diagnoses. Clinicians become frustrated when confronted with a patient complaining of diffuse, non-specific joint and muscle discomfort and having no apparent etiology or causative agent that can readily be identified. Moreover, the symptom pattern can change on an almost daily basis and can be modified by such factors as weather changes, sleep, and activity patterns. The current array of imaging tests such as conventional MRI, CT, PET, radiography or ultrasound, have aided little in elucidating the etiology—or even the existence—of MPS. The same can be said about conventional lab testing, with no bio-chemical markers being identified as reliable indicators for the presence or absence of MPS.

Magnetic Resonance Elastography (MRE)

MRE is a relatively new diagnostic test to enter the imaging arena and promises to be a potentially useful test to verify the existence of such entities as taut bands in muscles and trigger points, both of which are hallmark components of myofascial disorders and have been elusive in diagnosing accurately. It is estimated that well over 9 million people—both men and women—in the US suffer with MPS, a condition marked by widespread pain and tenderness in the trunk and extremities. MRE seeks to identify changes in muscle tone and stiffness or elasticity, and so is based on measurement of the mechanical characteristics of soft tissue.2 Abnormal changes in soft tissue such as is seen in many cancers, various masses/tumors (consolidation), mineralizing disorders (calcification), or simply in tight and sore muscles can now be identified and characterized by MRE. Malignancies tend to be much harder than normal tissues and benign tumors. This is especially evident in breast cancer tumors which are most often detected by physical examination on the basis of hardness followed by tissue biopsy.3

The use of this technology has not been limited to soft tissue diagnosis but includes using the same bio-physical principles to detect lesions in liver, breast, brain and cardiac tissue with studies currently underway investigating all these applications.4 It is thought that in the near future the use of MRE will increase significantly—especially for monitoring muscle stiffness related to muscle-wasting diseases such as multiple sclerosis and hyperthyroidism.5

The underlying premise of MRE is that normal or healthy tissue has a certain shear modulus or elasticity whose values fall within a specific range. It also appears that different muscles have different elasticity ranges with modifying factors being tissue temperature, muscle size, and age of muscle being tested.6 The implications of using MRE are significant, with the obvious one being that, to date, tissue palpation of superficial tissue is a useful and reliable method of tissue examination, but limited by what the physician can feel under his/her hand. Using MRE will allow greater depth of visualization and assessment by the examiner using magnetic resonance technology to aid in this process.

The use of existing MR technology has been instrumental in the development of MRE with this newest MR application being based on harmonic mechanical excitation in which an acoustic or sound wave is created and propogated within the target tissue. This shear wave, along with some of the key features such as wavelength, is measured and quantified for correlation to skeletal muscle using both relaxed and contracted muscle states. It is now understood that shear wavelength increases with increasing tissue stiffness and increasing tissue tension levels.7 Most recently, MRE has validated an existing mathematical model of human skeletal muscle behavior in the biceps brachii, correlated to EMG data in the distal leg muscles, and quantified the effects of pathologies on the distal and proximal leg muscles.8

MRE and Specific Muscle Applications

The news about MR application using elastography has not come soon enough for those practitioners who have specialized in the diagnosis and treatment of soft tissue dysfunctions, nor for the millions of persons who suffer with tight, sore, and tender soft tissue structures such as tendons, ligaments, connective tissue, and muscle. Fibromyalgic symptoms (pain, point tenderness, tightness) are a feature of several controversial pathologic entities and may also include taut bands and trigger points (TPs) as components of these syndromes. Physicians, physical therapists, massage therapists, chiropractors, and others have been identifying muscle banding and TPs during routine palpation of involved muscles in patients for many years. Until now, there has been no method of precisely characterizing these entities in superficial anatomical structures. It was simply a matter of whether a TP was present or not. Palpation of deep anatomical structures, however, is uncomfortable to the patient and notoriously unreliable as a method of assessment of banding and TPs.

The results of recent studies tend to suggest that deep taut bands of soft tissue can be detected and quantified using MRE technology. One study found that the stiffness level of taut bands in patients with myofascial pain may be 50% greater than that of surrounding muscle tissue, making taut band identification possible within the context of healthy muscle.9 MRE’s ability to accurately distinguish a symptomatic or pathologic taut band versus a more normal region of tightness has been replicated in studies by various groups. The taut band signature has been described as having a chevron shape due to the increased tension within the band.10 The increased attention that MRE has brought to both the architecture and mechanical properties of soft tissue seems to have envigorated trigger point research with new findings to help support the viability of a TP theoretical framework that explains not only anatomical variations of TP versus healthy tissue, but also some unique histo-chemical attributes of trigger points. In another study that compared the histo-chemical environment between trapezius muscles, with and without TPs, the authors found that the surrounding area of a TP-infested region had increased amounts of selected analytes—including inflammatory mediators, neuropeptides, cytokines, and catecholamines—than did the trapezius with non-active TPs.11

These biochemicals are associated with pain and inflammation and could help explain inflammation-mediated pain and point tenderness. The implications of these histo-chemical findings—combined with those utilizing MRE to visualize tissue changes—are significant for practicing clinicians and have the potential of being the foundation of a more robust treatment model based on verifiable and measurable findings, rather than simply relying on patient self-reports.

This new technology should also help in the quantification of treatment effects to better monitor tissue healing and the effectiveness of therapy. Of particular interest, MRE has been able to detect tissue tension level differences in muscle with active TP, painful muscle without TP, and non painful muscle—with representative shear modulus or elasticity measurements (in metric KiloPascals) equal to 9.0 kPa, 6.2 kPa, and 4.1 kPA, respectively. If research continues to support MRE’s ability to discriminate between tension levels of similar muscle groups in patients with and without TPs and/or painful soft tissue, this technology could advance the field of musculo-skeletal diagnostics significantly.12


It appears that MRE will provide valuable and unique diagnostic data for musculoskeletal syndromes that historically have proven to be diagnostic challenges. Given the current arsenal of available testing methodologies, it is refreshing to many that MRE seeks to capture and define the mechanical properties of stiffness and tension within soft tissue, properties that previously were described primarily by manual palpation. The movement toward a more objective form of testing for measurement of soft tissue tension or elasticity should appeal to a greater number of practicing clinicians who have been skeptical about acknowledging the very existence of syndromes such as fibromyalgia and myofascial dysfunctions. MRE should prove to be a useful diagnostic test for the detection of muscle dysfunction in general and, quite possibly, may play an unexpected role in uniting a fragmented medical community over the existence of such conditions as fibromyalgia.

Last updated on: January 5, 2012
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