New research suggests the pain experienced by people suffering from fibromyalgia is the result of a mismatch between parts of the brain and nervous system involved with the senses and those involved with movement.
The conclusion comes from a study conducted by researchers at the University of Bath and the Royal National Hospital for Rheumatic Diseases in the UK. The results of the study are published in the November issue of the journal Rheumatology.
The research team asked study participants to look at a reflection of one limb in a mirror whilst moving their other limb in a different direction which was hidden behind the mirror. The idea was to create a mismatch between what the brain sees though sensory input from the eyes and what it feels through the motor system that controls movement.
The procedure was then repeated without the use of a mirror so that results with and without sensory input could be compared.
The study involved 29 fibromyalgia patients and 14 healthy volunteers. The researchers found that of the 29 fibromyalgia patients 26 reported feeling a temporary increase in pain, a change in temperature, or a feeling of "heaviness" in the hidden limb when the mirror was used.
The feelings that the patients reported mimicked those that are experienced during a fibromyalgia flare up.
In contrast to the fibromyalgia patients, only half of the healthy volunteers reported any changes in sensation in the hidden limb.
The source of the pain experienced by fibromyalgia patients has confused doctors and researchers since it was first reported. The lack of any identifiable reason for the pain is a primary reason why those with fibromyalgia are often seen as malingerers and why some doctors still refuse to acknowledge the condtion even exists.
Lead researcher Dr. McCabe told the MedPage Today website: "We have shown that by confusing the motor and sensory systems we can exacerbate the symptoms felt by people diagnosed with the condition."
"This adds to a growing body of evidence that many of the symptoms of this common disorder may be perpetuated, or even triggered, by this sensory-motor conflict."
Last month another potential explanation for fibromyalgia pain was identified by another group of researchers. They found abnormalities in the opioid receptors in the nervous system. It is these receptors that allow certain opiate based painkilling drugs, as well as natural endorphins, to fight pain.
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Source: McCabe CS, et al "Somaesthetic disturbances in fibromyalgia are exaggerated by sensory-motor conflict: implications for chronicity of the disease?" Rheumatology 2007; 46: doi:10.1093/rheumatology/kem204.