Do Severity Score and Skin Temperature Asymmetry Correlate with the Subjective Pain Score in the Patients with Complex Regional Pain Syndrome?

Background: The diagnostic criteria of complex regional pain syndrome (CRPS) have mainly focused on dichotomous (yes/no) categorization, which makes it difficult to compare the inter-patient's condition and to evaluate the intra-patient's subtle severity over the course of time. To overcome this limitation, many efforts have been made to create laboratory methods or scoring systems to reflect the severity of CRPS; measurement of the skin temperature asymmetry is one of the former, and the CRPS severity score (CSS) is one of the latter. However, there has been no study on the correlations among the CSS, temperature asymmetry and subjective pain score. The purpose of this study was to evaluate whether there is any correlation between the CSS, skin temperature asymmetry and subjective pain score. Methods: Patients affected with CRPS in a unilateral limb were included in this study. After making a diagnosis of CRPS according to the Budapest criteria, the CSS and skin temperature difference between the affected and unaffected limb (${\Delta}T$) was measured in each patient. Finally, we conducted a correlation analysis among the CSS, ${\Delta}T$ and visual analogue scale (VAS) score of the patients. Results: A total of 42 patients were included in this study. There was no significant correlation between the ${\Delta}T$ and VAS score (Spearman's rho = 0.066, P = 0.677). Also, the CSS and VAS score showed no significant correlation (Spearman's rho = 0.163, P = 0.303). Conclusions: The ${\Delta}T$ and CSS do not seem to reflect the degree of subjective pain in CRPS patients.