Abnormal Pain Memory Helps To Explain Fibromyalgia

Fibromyalgia, sometimes called fibrositis, is associated with widespread pain, stiffness and fatigue. People with fibromyalgia are found to have multiple tender points in specific body areas. The painful disorder affects about two percent of the U.S. population.

Researchers at the University of Florida applied heat stimuli to the hands of healthy controls and fibromyalgia patients. In contrast to normal controls, fibromyalgia patients experienced a great amount of cumulative pain from these stimulations, indicating abnormalities in spinal cord pain processing. Furthermore, the fibromyalgia patients experienced residual pain when the stimuli were applied at intervals at which the healthy controls were not affected. Normally, pain sensations quickly subside after a single heat stimulus, but will accumulate with repetitions if they occur frequently enough. This "pain memory" appears to linger for an abnormally long period of time in fibromyalgia patients.

The researchers also found that the residual pain experienced by fibromyalgia patients was widespread and not limited to a single area of the body.

"Because the effect of the first experimental stimulus does not rapidly decay in fibromyalgia patients, the effect of subsequent stimuli adds to the first, and so on, resulting in ever increasing pain sensations," said lead investigator Roland Staud, MD. "Our findings provide evidence for abnormal central nervous system mechanism of pain in fibromyalgia patients and have significant implications for future therapies, which need to target these abnormal central pain mechanisms."

The American College of Rheumatology is the professional organization for rheumatologists and health professionals who share a dedication to healing, preventing disability and curing arthritis and related rheumatic and musculoskeletal diseases. For more information on the ACR's annual meeting, see http://www.rheumatology.org