Skin conductance, temperature, and blood flow in causalgia

To test the hypothesis that causalgia is a reflex sympathetic dystrophy with focal sympathetic hyperactivity in the painful area, we studied skin conductance, temperature, and a radiometric index of blood flow in 10 patients and 10 controls. Skin conductance was significantly higher, and both skin temperature and blood flow index were significantly lower in the patient extremities. When the affected and homologous, non-affected extremity values were compared, asymmetries were more common and of larger magnitude in the patient group. There was no consistent pattern of asymmetry. These results do not support the hypothesis that causalgia is a reflex sympathetic dystrophy.