Fibromyalgia - Researching the Cause

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Fibromyalgia was mostly unrecognized, as recently as thirty years ago. The symptoms of fibromyalgia syndrome which include muscle pain and chronic fatigue led people on a quest for help.

Clinical examinations often revealed no concrete physiological findings. X-rays, blood tests, and muscle biopsies appeared normal, and therefore the symptoms seemed unexplainable. The patient was frequently told the symptoms were "all in their head."

Psychological stresses have long been regarded as contributory to fibromyalgia syndrome, but now much new research is ongoing. Better physiological and biological evidence is being gathered.

Sleep Abnormalities and Fibromyalgia

In 1975, two Canadian physicians and researchers, Harvey Moldofsky, MD, and Hugh Smythe, MD, were asked by colleagues at the University of Toronto to interview patients complaining of chronic muscle pain for which no physiological cause could be found. Following the interviews, the two Canadian researchers suspected sleep abnormality and further studied the patients using EEG (brain wave test). The device measured the patients brain waves during sleep and it was found that the patients had a deficiency in the deepest stage of sleep, known as stage 4.

The researchers continued studying sleep disorder as a factor in fibromyalgia. One of their studies involved awakening healthy people and disrupting their sleep pattern as they entered stage 4 of sleep.

Interestingly, it was found that the healthy subjects developed fibromyalgia symptoms when their sleep was disturbed, but the symptoms subsided when they were permitted to sleep undisturbed.

As the two researchers analyzed the study results, they concluded that the patients not only had sleep abnormalities but also had disregulation of normal body circadian rhythms affecting periods of wakefulness too.

Muscle Abnormalities and Fibromyalgia

Until about thirty years ago, fibrositis was the term used rather than fibromyalgia. Fibrositis was an incorrect term because it means muscle inflammation, and it is now known that inflammation does not exist in the muscles of fibromyalgia patients. In the early 1980's some researchers described varied muscle biopsy abnormalities in people with fibromyalgia but by 1989 a controlled, blinded study was done which revealed an opposite conclusion that there were no more muscle abnormalities in fibromyalgia patients than in pain-free control subjects.

In 1986, a team of researchers from Sweden theorized that the muscle pain of fibromyalgia is a result of tissue hypoxia because of the inability of the muscles to functionally use oxygen. It is thought to this day that this applies to some patients.

Robert Bennett, MD, from Oregon, along with other researchers have analyzed the connection between sleep disorders and muscle damage. Growth hormone which is important in muscle maintenance and repair is secreted during sleep stage 4. The research of Dr. Bennett indicates that about one-third of fibromyalgia patients have a growth hormone deficiency.

Substance P and Serotonin

There has been some research which has focused on the chemicals of the nervous system which help regulate pain messages sent out to brains.

Two such chemicals are:

  • Substance P
  • Serotonin

According to A.D.A.M, "Substance P is a neurotransmitter associated with increased pain perception." Normally, substance P begins the pain signal process which follows painful tissue injury.

According to A.D.A.M, "Serotonin is synthesized from the amino acid tryptophan by enterochromaffin cells in the stomach and bronchi (lungs)." Serotonin normally reduces the intensity of pain signals. Serotonin has also been found to play an important role in sleep regulation. There are studies which show abnormal levels of both of these hormones in people with fibromyalgia.

Research also has described some people with fibromyalgia as having decreased blood flow to certain areas of the brain which help modulate pain signals sent from the spinal cord to the brain. The theory that some people with fibromyalgia have exceptionally high-intensity pain messages sent to the brain, along with a deficiency in pain inhibition, is supported by the research indicating abnormal levels of substance P and serotonin and decreased brain blood flow.

Hormones and Fibromyalgia

Researchers also have taken the fact that fibromyalgia is more common in women than men and suggested that the sex hormone estrogen is involved. However, little correlation has been discovered. It also has been suggested that the lower levels of testosterone in women than in men is more likely involved since testosterone is involved in building muscle strength.

A team of researchers from Massachusetts found that cortisol levels are low in people with fibromyalgia.

Cortisol is produced by the adrenal gland and affects many bodily systems. Low levels of cortisol are ever present in the body but we produce more during times of stress. When the body is deficient in cortisol, the symptoms of fibromyalgia are mirrored, such as:

  • fatigue
  • weakness
  • muscle pain
  • abdominal distress
  • thinking problems
  • mood swings
  • sleep disturbances

The research team from Massachusetts found that fibromyalgia patients produce less cortisol in response to stress than do healthy people, possibly having to do with a defect in the hypothalamic-pituitary-adrenal axis which controls cortisol production. It is not clear how important cortisol deficiency is in the onset or course of fibromyalgia. Giving patients corticosteroid medications does not improve the condition.

Genetics and Fibromyalgia

The relationship between children and parents having either fibromyalgia or other pain related problems has led some researchers to suggest a genetic cause.

Particular genetic markers have been mentioned, but those markers have been different in different studies. Most recently HLA, human leukocyte antigen markers, have been implicated. Another study published in 1996 proposed that fibromyalgia is more common in people who have a family history of alcoholism and depression.

 Biological and genetic factors have been studied in these areas as well.

Relationship to Autoimmunity

Since fibromyalgia is often diagnosed in people with autoimmune diseases such as rheumatoid arthritis and lupus erythematosus, it has been theorized that fibromyalgia has an immune system basis too. One study indicated an increased number positive antinuclear antibody blood tests among people with fibromyalgia. This finding may be coincidental though since it is known that a small percentage of healthy people are also positive for antinuclear antibodies (ANA).

The high prevalence of fibromyalgia in the general population may suggest that its occurrence in people with autoimmune disease is purely coincidental. Conversely, some forms of the over 100 known types of arthritis may be related to muscle pain and fatigue. Some researchers conclude then that if physiologic stress is truly a factor in fibromyalgia, the physical and emotional toll of having a chronic disease may precipitate fibromyalgia in people with some arthritis-related diseases.

The Bottom Line - The Cause of Fibromyalgia Syndrome?

Fibromyalgia is most likely the result of different causes, only time will tell.

In terms of treating fibromyalgia syndrome, it can be compared to conditions such as hypertension - a condition not completely understood, yet treatable.


Fibromyalgia-Syndrome of the 90's, by Mary Anne Dunkin, Arthritis Today, September-October 1997

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