Lower-Back and Fibromyalgia Pain Linked, Possible Source Identified
By Bruce Sylvester
NEW ORLEANS, LA -- October 28, 2002 -- Lower back pain appears to be caused by a malfunctioning pain pathways in the brain, in a manner similar to fibromyalgia pain, University of Michigan researchers report.
"These patients get bad reputation for claiming to feel pain in places where no physiological cause can be identified. It looks like the pain has a physiological source indeed, but in problems in the brain," said investigator Richard Gracely, Ph.D, professor of rheumatology at the University of Michigan School of Medicine in Ann Arbor told United Press International.
The research was presented yesterday at the annual meeting of the American College of Rheumatology in New Orleans.
The investigators enrolled 15 subjects experiencing chronic lower-back pain with no apparent physical cause, such as muscle, joint or bone injury. They also recruited 15 fibromyalgia patients and 15 normal control subjects.
All subjects underwent functional magnetic resonance image (fMRI) scanning simultaneous with having a device apply pulsing pressure to the base of their left thumbnail. The variable pressure included painful and non-painful levels. The researchers noted that mild pressure caused subjects with lower-back pain and fibromyalgia to report significant pain, while control subjects tolerated the same pressure with little pain.
Among the back pain and the fibromyalgia patients, the same mild pressure caused brain responses in areas that process the sensation of pain. The same brain responses did not happen in control subjects until pressure was raised substantially.
All subjects showed increased activity in eight areas of the brain, but lower-back pain subjects showed no increased activity in two areas that were active in both fibromyalgia subjects and normal control subjects. The fibromyalgia subjects showed increased activation in two other areas not active in back pain patients and healthy subjects.
The study indicated that lower-back pain patients have enhanced pain response in some brain regions, and diminished response in others, the investigators reported. The study offers the first objective method for correlating lower-back pain to unique brain activities at the precise moment of adverse feeling.
The research might eventually lead to better treatments for lower back pain and fibromyalgia, by pointing toward certain brain regions where pain-inducing disorders might be located, Dr. Gracely noted.
"So the bottom line is that fibromyalgia pain and lower-back pain are really 'real,'" said Nancy Derby, spokesperson and director of public policy and education for the National Fibromyalgia Association in Orange, CA. "This pain is a moving target, it seems, and perhaps now we see a bit better where it comes starts."
Lower back pain is common, especially among overweight and sedentary people and those whose work is physically demanding. Lower back pain and problems stemming from it rank as the second most frequent cause of lost workdays in adults under the age of 45, second only to the common cold.
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