immunesupport.com: "The underlying cause of fibromyalgia remains unknown, but in the past 25 years substantial progress has been made toward understanding the mechanisms behind specific features of fibromyalgia, Staud said. One is central sensitization, a feature of many chronic pain conditions in which the central nervous system - the brain and spinal cord - somehow magnifies pain signals to abnormally high levels, said Staud, who is affiliated with UF's McKnight Brain Institute.
Central sensitization is associated with wind-up, a phenomenon in which repeated touches - even handshakes or pats on the back - generate lingering pain that increases with each new contact, he said. A normal form of achy, lingering pain known as secondary pain affects anyone who suffers an injury.
The UF researchers - Staud, neuroscientist Charles Vierck, Ph.D., psychologist Michael Robinson, Ph.D., and Donald Price, Ph.D. - were surprised to learn that dextromethorphan eased fibromyalgia patients' wind-up pain to the same degree it soothed secondary pain induced in healthy volunteers, Staud said. The results indicate a long-suspected cause of wind-up may not exist.
Previous studies at other institutions had shown that dextromethorphan blocks the action of a chemical messenger called N-methyl-D-aspartate, or NMDA, which relays pain impulses in the spinal cord. Many fibromyalgia researchers have theorized that wind-up is caused by abnormalities in the spinal-cord structures that process NMDA.
The UF results suggest those structures function normally but that pain impulses are more amplified in fibromyalgia than in healthy participants, Staud said.
'This has refocused much of our research now,' he said. Future UF studies will attempt to pinpoint where the pain impulses are originating. "