Myofascial pain syndrome is one of the more prevalent yet widely misunderstood pain syndromes. Myofascial pain syndromes are those syndromes which involve pain caused by the presence of trigger points in muscles. Myofascial pain syndrome actually means pain that is caused by the muscle or the fascia surrounding the muscle.

Myofascial pain syndromes are said to account for approximately 70% of the disability in North America. Myofascial pain syndromes are commonly seen in clinical practice as headaches, arm pain, back pain, and misdiagnosed commonly as sciatic pain of the legs.

Myofascial pain occurs when a trigger point forms in a muscle. A trigger point is a locally tender palpable spot that is hypersensitive to touch. Upon palpation or pressure, it causes a well defined pain pattern specific for that muscle. During a heart attack, pain is very often reported in the left arm and is commonly referred to as diagnostic of a heart attack. Trigger points in muscle cause similar types of patterns, very distinct in nature. For example, a trigger point in the neck or upper shoulders may cause a headache pattern in which the people may feel the pain in the forehead or sides of the head.

It is not clear what causes trigger points to develop, although the research would indicate that trigger points develop in muscles that are overworked, overused, fatigued, chilled and/or injured. In addition, there can be secondary factors such as arthritis, joint dysfunction, visceral disease, and emotional factors which can indirectly effect that pain. Once the trigger point (myofascial pain syndrome) is established, there are several perpetuating factors that will contribute to the maintenance of the pain pattern. These include poor posture, poor diet, smoking, and continued overuse of the affected muscle.

Once a trigger point is developed, it can cause the development of secondary trigger points in other muscles within the same area. For example, a trigger point in the upper trapezius in the neck may ultimately cause the development of a trigger point in the scalene which lays beside the upper trapezius. Once the trigger point develops, if the problem is not corrected, and there are perpetuating circumstances, this syndrome appears to spread and develop, possibly throughout the entire body.

Trigger points can be both active and latent. When they are active, they cause well defined pain patterns (as mentioned above). When they are latent, they will very often only be felt as sore or tender on that spot. They may cause reduced range of motion but otherwise are clinically insignificant. It is thought that overexertiott or over-utilization of the particular muscle causes the trigger point to change from latent to active. Rest will reverse this process, often leading to a reported cycle of "when resting and relaxed I don't hurt and when I go to move or do something my pain returns". This is a very characteristic clinical complaint and is often interpreted by professionals as meaning stress is the cause (which it is not).

Medical examination of the individual with myofascial pain syndrome is often inconsistent. Sometimes there may be the presence of muscle spasm, although this is not seen in all individuals. They will often report with some tenderness known as a 'taut band' in which the fibre of the muscle can actually be felt. In addition, when pressure is applied to the trigger point a twitch response is produced in which the individual reacts to the pressure through twitching or involuntary movement. Further medical examination will often indicate an asymmetry of the bony structure in the body, for example a winging of the scapula or rotation and misalignment of the hips. It is not known if this causes he development of trigger points in these muscles or is secondary, but once in evidence needs to be treated appropriately.

Electromyography offers an objective way of documenting the presence of trigger points, and of reregulating the disregulated muscle. The presence of trigger points is indicated by increased electrical activity as documented by the electromyographic assessment. As biofeedback treatment progresses, this electrical activity changes, serving as an objective measure for treatment efficacy and outcome. Two forms of electromyographic biofeedback treatments are currently in use: dynamic and static (or resting). Static procedures are used to indicate muscle tension. These procedures are usually used in conjunction with other techniques such as relaxation training, postural training, and psychotherapy. Dynamic EMG procedures may be used to change the electrical characteristics of the muscles at work, altering biomechanical imbalances, and achieving motor control.

Electromyographic assessment techniques are also used to document and objectify the results of related treatment of trigger points, allowing for more exact treatment and thus leading to reduced health care costs. Typical reductions in treatment costs are in the 70% range with chronic trigger point problems, and in the 90% range for the more acute injury.

The presence of trigger points is now starting to be well understood in terms of the electrical characteristics of muscle activity. Electromyography, in particular, offers an exciting new way of documenting and healing disregulated muscle, allowing for efficacious treatment of muscular dysfunction.

Travell, J., and Simons D. Myofascial Pain and Dysfunction; the Trigger Point Manual. Baltimore/London: Williams & Wilkins, 1983.

Hubbard, D.R., and Berkoff, G.M. Myofascial Trigger Points Show Spontaneous Needle EMG Activity. Spine. 1993:18(13)1803-1807.

Donaldson, S. Skubick, D.L., Clasby R.G. Cram JR., The Evaluation of Trigger-point Activity Using Dynamic EMG Techniques. AJPM, 1994:4 (3) 118 - 122.

© 1995
Association for Applied Psychophysiology and Biofeedback