The role of peripheral sudomotor blockade in the treatment of patients with sympathetically maintained pain.

The aim of the present study was to investigate the role of the peripheral cholinergic system in patients with sympathetically maintained pain (SMP). Thirty-three patients with SMP were given Bier's block with 0.6 mg of atropine in 10 ml of saline or 10 ml of saline in a randomised double-blind manner. Pain intensity, pain relief and mood were assessed before and after each block using the visual analogue scale (VAS). In addition pain intensity was assessed at the same time using a categorical scale (CS). There was at least 1 week between each injection, and during this week the patients reported their pain intensity daily, using the CS. Three patients failed to complete both wings of the study and thus the results of the remaining 30 patients were analysed using the Mann-Whitney U test and the Wilcoxon signed-rank test. No significant difference was found between atropine and saline on any parameter.