Vasodilative effect of lsosorbide dinitrate ointment in complex regional pain syndrome type 1

Background: In complex regional pain syndrome type 1 (CRPS1) vascular changes occur from the initial, inflammatory event onto the trophic signs during chronicity of the disease, resulting in blood flow disturbances and marked temperature changes. Pharmaco therapeutic treatment is generally inadequate. Aim: To determine whether local application of the nitric oxide donor isosorbide dinitrate (ISDN) could cause vasodilation and thereby improve tissue blood distribution in the affected extremity. Methods: In a pilot study, 5 female patients with CRPS1 in one hand were treated with ISDN ointment 4 times daily during 10 weeks. As a primary objective video thermography was used to monitor changes in blood distribution in both the involved and contralateral extremities. Results: Patients treated with ISDN showed an increase of 4 degrees C to 6 degrees C in mean skin temperature of the cold CRPS1 hands, reaching values similar to that of the contralateral extremities within 2 to 4 weeks time, suggesting normalization of blood distribution. This was confirmed by an improvement in skin color. In 3 patients the Visual Analog Scale pain declined, whereas in the other 2 patients the Visual Analog Scale pain was unchanged over time. Conclusions: In this pilot study, topical application of ISDN seems to be beneficial to improve symptoms for patients with cold type CRPS1, but further study is needed.