Investigation of cutaneous microvascular activity and flare response in patients with fibromyalgia syndrome

Objectives. To assess microvascular activity in the skin of patients with f ibromyalgia syndrome (FMS,) as compared with normal controls. Methods. Fifteen patients, who fulfilled the American College of Rheumatolo gy criteria for FMS, and 15 age- and sex-matched healthy controls, were stu died. The microvascular activity of the skin overlying the trapezius muscle was quantified using iontophoresis of acetylcholine as an endothelial-depe ndent vasodilator and sodium nitroprusside as an endothelial-independent va sodilator. We also studied the flare response by iontophoresing acetylcholi ne continuously for 10 min to stimulate a ring of nociceptor c-fibre ending s in the skin. Results. There was no significant difference in cutaneous vascular response s to short-duration iontophoresis of acetylcholine and sodium nitroprusside at the three different doses used. The area under the curve (AUC) (mean +/ - S.E.M..) for acetylcholine baseline, 20, 40, and 80 s were 6 +/- 0.7, 23 +/- 6, 45 +/- 7 and 66 +/- 10 AU for patients and 11 +/- 4, 24 +/- 3, 49 +/ - 7 and 62 +/- 12 AU for controls, respectively (P = 0.2, 0.9, 0.7, 0.8, re spectively). The corresponding figures for sodium nitroprusside were 5 +/- 1, 18 +/- 7, 51 +/- 14 and 68 +/- 14 AU for patients and 8 +/- 3, 13 +/- 2, 39 +/- 5 and 61 +/- 9 AU for controls, respectively (P = 0.2, 0.5, 0.4, M, respectively), There was also no significant difference in the flare respo nse in patients with FMS as compared with control subjects (119 +/- 15 and 131 +/- 13 AU, respectively; P = 0.57). Conclusion. There are no significant differences in cutaneous microvascular reactivity between patients with FMS and control subjects.