Myosymmetries Calgary - Myofascial Pain Syndrome

Myofascial pain syndrome evolves when a trigger point develops in a muscle. This occurs when a muscle is:

overworked and fatigued
overloaded
chilled
grossly traumatized

These factors are considered as direct causes, while other factors (other trigger points, arthritic joints, visceral disease, and emotional stress) are considered as indirect causes; that is , they create a situation which then causes the development of the triggerpoint.

Recent anatomical studies have indicated that trigger points develop due to disturbance(s) of the peripheral nervous system or the central nervous system.

locally tender to touch
contained in a taut band in the muscle
produces a local twitch response
produces referred pain in a well defined pattern

The source of the pain is a trigger point, which may be latent or active dependent upon the individual's activity level. A latent trigger point when present in a muscle produces pain upon palpation, usually is associated with reduced range of motion, and once developed tends to remain so until treatment is completed. The latent trigger point becomes active with exertion of overloading causing a well defined pain pattern.

This referred pain is produced in a heart attack when the left arm develops pain. These referred pain patterns are well developed in nature, reproducible, and consistent from person to person.

It is easy to see why this type of pain is often considered to be psychogenic in nature, as activity (equated to stress) will increase the pain and rest (equated to reduced stress) reduces it.

Despite this knowledge, myofascial pain syndrome remains poorly recognized as a clinical entity. There are several reasons for this.

First, there is no medical specialty that calls muscles its own. For example, nerves have neurology and the mind has psychiatry. Physiatry, a medical discipline devoted to rehabilitation, is just starting to emerge as a strong specialty but even then not all graduates are well trained in myofascial pain syndromes.

Second, historically, there has been no clear definition of myofascial pain syndromes. The terminology for muscle pain has included myofascial pain, fibromyalgia, fibrositis, etc., producing a confusion of terms and dysfunction and study outcomes. Myofacial pain syndromes and fibromyalgia are two separate entities with each having their own pathology, but sharing the muscle as their common pathway of pain.

Third, because the pain is referred and not understood as such, when the painful areas are examined there is little or no anatomical evidence to match the pain. Thus, the pain is often thought to be psychogenic (in the head) of those involved in litigation and is supposed to disappear when compensation is paid (but often does not).

Fourth, the pain patterns do not seem to have a physiological foundation as the reported pain does not correspond to known neural connections.

Finally, much attention has been given to the development of tools which objectify pathology in bones, nerves, and organs (i.e. X-rays, MRIs). Until recently, there has been little in the way of tools to provide objective evidence to verify the presence of trigger points.

The development of needle and surface EMG techniques has started to alleviate this problem. For example, Hubbard and Berkoff (1993) using needle electrodes demonstrated that trigger points are electrically hyper-active parts of a muscle involving the muscle spindle fibers.

Donaldson et al (1994), using surface EMG techniques (sEMG), demonstrated that the muscle which contains trigger points was hyper-active when compared to the contralateral partner (the same muscle on the opposite side of the body).