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Effect of tadalafil on blood flow, pain, and function in chronic cold complex regional pain syndrome: a randomized
George Groeneweg1, Frank J P M Huygen, Sjoerd P Niehof
1Department of Anesthesiology, subdivision Pain Treatment Centre, Erasmus MC, Rotterdam, the Netherlands. j.groeneweg@erasmusmc.nl
Background:
This double-blind, randomized, controlled trial investigated the effect of the phosphodiesterase-5 inhibitor tadalafil on the microcirculation in patients with cold Complex Regional Pain Syndrome (CRPS) in one lower extremity.
Methods:
Twenty-four patients received 20 mg tadalafil or placebo daily for 12 weeks. The patients also participated in a physical therapy program. The primary outcome measure was temperature difference between the CRPS side and the contralateral side, determined by measuring the skin temperature with videothermography. Secondary outcomes were: pain measured on a Visual Analogue Scale, muscle force measured with a MicroFet 2 dynamometer, and level of activity measured with an Activity Monitor (AM) and walking tests.
Results:
At the end of the study period, the temperature asymmetry was not significantly reduced in the tadalafil group compared with the placebo group, but there was a significant and clinically relevant reduction of pain in the tadalafil group. Muscle force improved in both treatment groups and the AM revealed small, non-significant improvements in time spent standing, walking, and the number of short walking periods.
Conclusion:
Tadalafil may be a promising new treatment for patients that have chronic cold CRPS due to endothelial dysfunction, and deserves further investigation.
Trial Registration:
The registration number in the Dutch Trial Register is ISRCTN60226869.
