Microvascular arteriovenous shunting is a probable pathogenetic mechanism in erythromelalgia.

Erythromelalgia is a condition consisting of red, warm, and burning painful extremities. Symptoms are relieved by cold and aggravated by heat. A wide variety of etiologic conditions can cause erythromelalgia, but one common pathogenetic mechanism, microvascular arteriovenous shunting, has been hypothesized. The aim of this study was to test this hypothesis. Quantification of skin microvascular perfusion using laser Doppler perfusion imaging and skin temperature at rest and after central body heating was performed in 14 patients with erythromelalgia and 11 controls. Attacks of erythromelalgia were induced in eight patients after heat provocation. In the plantar region of the foot, the location of numerous anatomical arteriovenous shunts, these patients significantly increased the skin perfusion as compared with asymptomatic patients with erythromelalgia and controls. In the dorsal region with few arteriovenous shunts no significant differences between the groups were demonstrated. The results show a relation between clinical symptoms and increased perfusion in the region of numerous anatomical arteriovenous shunts, and support the hypothesis of increased thermoregulatory arteriovenous shunt flow during attacks in primary erythromelalgia.