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 p athogenetic mechanism, microvascular arteriovenous shunting, has been hypot hesized. The aim of this study was to test this hypothesis. Quantification of skin microvascular perfusion using laser Doppler perfusion imaging and s kin temperature at rest and after central body heating was performed in 14 patients with erythromelalgia and 11 controls. Attacks of erythromelalgia w ere induced in eight patients after heat provocation. In the plantar region of the foot, the location of numerous anatomical arteriovenous shunts, the se patients significantly increased the skin perfusion as compared with asy mptomatic 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 a nd increased perfusion in the region of numerous anatomical arteriovenous s hunts, and support the hypothesis of increased thermoregulatory arterioveno us shunt flow during attacks in primary erythromelalgia.