Comparison of sympathetic activity by use of skin conductance monitor in patients with and without complex regional pain syndrome

Abstract

Aim: Sympathetic system dysfunction has been described among the theories involved in the pathophysiology of complex regional pain syndrome. Objective measurement of the sympathetic activity of the affected extremity in patients with complex regional pain syndrome has not been compared to normal subjects in the literature. The skin conductance monitor is a non-invasive monitor that can objectively measure sympathetic skin activity of the extremity. In this study, we aimed to compare the differences in sympathetic activity of extremities in subjects with and without complex regional pain syndrome by using a skin conductance monitor. Material and Methods: Sympathetic skin responses were evaluated in 63 subjects, including 25 measurements on the affected extremities in 13 patients with lower extremity complex regional pain syndrome type 1 and 50 measurements in 50 normal subjects in the control group. Among the skin conductance indices, the "peaks per second (0.02)" index was used as the main sympathetic skin response index. Descriptive criteria and the mean values of sympathetic skin response measurements were compared. Results: When sympathetic skin responses were compared with a skin conductance monitor using the "peaks per second (0.02)" index, no statistically significant difference was found between the complex regional pain syndrome and control groups in terms of sympathetic activity in the extremities (p=0.837). Conclusion: In this study, skin sympathetic nerve activity in the affected limb of patients with complex regional pain syndrome was similar to normal subjects. Further studies are required to assess the changes in sympathetic activity in complex regional pain syndrome.