Distribution of IL-6 and TNF-α. Distribution of a) IL-6 data and b) TNF-α data from 29 CRPS patients, from both the involved and the contralateral extremity. In each plot, the straight line indicates per definition a CRPS to contralateral ratio of 1.00 in case no difference was observed. Values are plotted on logarithmic scales. c) Box plots of these data, indicating the median, 25–75% interval and the ranges of values, excluding outliers. The Wilcoxon signed ranks test was used to assign differences in paired samples (blister fluid obtained from the CRPS1 and the contralateral extremity in the same patient).