Chronic Myofascial Pain Etiology

Muscles can develop trigger points because of accident, surgery, poor posture, repetitive motion, stress, or chronic tension; and can cause changes in balance, vision, and hearing. Untreated trigger points (TrPs) can affect the body to the point of dizziness and nausea. Untreated chronic myofascial pain from trigger points can cause heart palpitations, bowel and gonad related difficulties, urinary difficulties, and many other autonomic disruptions to the body.

Dr. Hong showed in 2002 (see resources) that a trigger point has both a sensory and motor component. These are demonstrated by locating tenderness, locating a referred pain pattern, and demonstrating a local twitch response by mechanical stimulation. He also believes sensitivities can be widely distributed in the muscle but seem to be mostly concentrated in the endplate. An active location is a site from which spontaneous electrical activity (SEA) can be recorded. This record is achieved much like heart electrical activity is recorded on an EKG. Trigger points are always found in taut bands of muscle and are histologically related to contraction knots caused by excessive endplate release of acetylcholine, a neurotransmitter found in the central and peripheral nervous systems. Dr. Hong's conclusion is that trigger points appear to be the result of "a serious disturbance of the nerve endings and the contractile mechanisms at multiple dysfunctional end plates."

There is also the energy crisis theory. This theory suggests that when the tissue is deprived of normal metabolic activity, it causes oxygen deprivation, which increases the metabolic demand already in short supply, thereby, creating a crisis. This concept investigated by Dr. Simons does not refute the theory of endplate dysfunction, but is part of it.

Chemicals, such as acetylcholine, are transmitted via the nervous system and are called neurotransmitters. They determine the elasticity of tissue by sending and receiving information along the neurological pathway. This would be much like ingoing and outgoing mail along an information highway. We now know that trigger points found in chronic myofascial pain (CMP) are due to the localized area craving oxygen, because the muscle where the trigger point (TrP) is located is in a perpetual energy crisis. This crisis causes the body to respond. Dr. Mohammed Yunus (1988), (see resources), has been studying chronic pain syndromes for a number of years and he believes that fibromyalgia and chronic myofascial pain may be similar in that they both cause muscle pain and tenderness, however, that is where the similarity ends.

It is well understood what happens at the trigger points associated with chronic myofascial pain. This, however, does not explain why the trigger point develops. Newer studies are indicative of an intensified pain state in chronic myofascial pain patients associated with abnormal brain activity suggesting a central sensitization as seen in fibromyalgia and chronic fatigue immunodysfunction. As studies progress, so are new hypotheses developed, such as Dr. Gerwin’s channellopathy hyopothesis (a dysfunction in one of the ion channels, specifically the ryanodine-receptor-calcium channel), see the reference below.

The etiology of myofascial trigger points (TrPs) causing chronic myofascial pain is suggestive of nerve chemical (neurotransmitter) disruption between the nerve ending and the muscle it affects. New evidence is leading to a central nervous system component. Understanding why these disruptions occur is what guides scientists. I suspect future hypothesis will focus on the relationship of sympathetic nervous system dysfunction and peripheral tissue disturbance. Once we understand what causes myofascial trigger points, we will be better able to prevent their development. The good news, unlike in fibromyalgia (FM) and chronic fatigue immunodysfunction (CFID), trigger point treatment is precise and successful when done properly.