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Study: Fibromyalgia sufferers' pain is mainly in the brain

November 3, 2008 | 11:57 am

The pain that is the hallmark of the condition called fibromyalgia doesn't show up on images and scans of muscle and bone -- a fact that has led many sufferers to be dismissed as hypochondriacs. But it is there in the brain for all to see -- all, at least, who happen to have a Single Positron Emission Computed Tomography imaging machine (and who know how to use it).

Pain researchers in Marseilles, France, writing in the November issue of the Journal of Nuclear Medicine, report that SPECT imaging revealed significant differences in the brain function of 20 women diagnosed with fibromyalgia and 10 healthy women used as controls. The SPECT technology allows precise measurements of blood flow to different parts of the brain -- and hence, of electrical activity. And in women with fibromyalgia, the parts of the brain responsible for discriminating degrees of pain were significantly more active than among normal, healthy women. Fibromyalgia sufferers had far lower levels of activity in the parts of the brain widely believed to process emotional responses to pain, the French researchers found. The more severe the subject's reported symptoms, the more pronounced were the differences in cerebral blood flow, the group found.

Dr. Eric Guedj, lead author of the study, said his findings reinforce the growing acceptance of fibromyalgia as "a real disease/disorder," and suggested that the disorder "may be related to a global dysfunction of the cerebral pain-processing."

While symptoms of depression or anxiety are frequent among fibromyalgia sufferers, the French researchers found that the abnormalities in brain function they found appeared to be present whether or not the subject experienced depression and/or anxiety as well.

Fibromyalgia -- characterized by chronic muscle and joint pain, fatigue and depression -- is thought to affect as many as one in 50 Americans, and is one of the most common causes of pain and disability. From 80% to 90% of those diagnosed are women.

The FDA recently approved the prescription pain medication Lyrica for those diagnosed with the syndrome -- a first medication approved for that indication. Researchers last year found that the anticonvulsant drug gabapentin can be successful in treating its symptoms. In addition to yielding clues to fibromyalgia's origins, Guedj and his colleagues suggest that SPECT imaging will help in the development and testing of new drugs to treat the disorder.

-- Melissa Healy