Infrared Thermographic Pattern of Lower Limb Complex Regional Pain Syndrome (Type I) and its Correlation with Pain, Disease Duration and Clinical Signs

Abstract

Purpose: So far, the use of infrared-thermography in the diagnosis of the Complex Regional Pain Syndrome (CRPS) has been described only for the upper extremity or jointly for the upper and lower extremity. Therefore, the aim of this study was the assessment of the absolute temperature side-to-side difference by infrared thermography in patients with CRPS Type I of the lower limb. It was investigated whether there are correlations between the amount of temperature side-to-side difference, pain, duration of the disease and clinical signs. Materials and Methods: 25 women and 11 men (mean age 48 years), who fulfilled the Budapest clinical criteria of CRPS type I, were investigated in this retrospective cross-sectional study. Infrared thermographic evaluation of the big toe, dorsal foot, ankle and distal anterior lower thigh was performed. The arithmetical mean of the absolute side-to-side differences of these 4 regions of interest was calculated=average side-to-side temperature difference of the distal lower limb. The correlation of the average side-to-side temperature difference of the distal lower limb with pain, duration of the disease and clinical signs (sensory, vasomotor, sudomotor/edema and motor/trophic) was assessed. Results: The average absolute side-to-side temperature difference of the distal lower limb was 1.6/1.2°C (mean/SD). A significant correlation between the temperature asymmetry was observed with the vasomotor signs. Conclusions: Infrared thermography offers an objective assessment of vasomotoric dysfunction in CRPS type I of the lower limb, and therefore serves as a useful supplementary tool in the diagnosis of CRPS type I.