Increased neurogenic inflammation in fibrositis syndrome.

Mechanically induced vasodilatation or flare on the skin, known as dermatographia, is a common clinical observation in fibrositis syndrome and is thought to be a neurogenically mediated axon reflex response. In our study, mechanically and chemically induced flares were quantitated in 13 patients with fibrositis syndrome and 14 control subjects. There was a reduced threshold for chemically induced flare response and the area of flare was greater in patients compared to controls, although there was a wide range of responses in both groups. There was also a significant positive correlation between mechanically and chemically induced flares, and the number of tender points in all subjects correlated with the size of the chemically induced flare. We suggest that exaggerated neurogenic inflammatory responses in patients with fibrositis syndrome reflect increased activity of polymodal nociceptors of unmyelinated primary afferent nerves. This increased receptor activity may also contribute to the pain and tenderness experienced by these patients.