Objective: The pathophysiology of Complex Regional Pain Syndrome type I (CRPS I) is unclear. An inflammatory reaction may cause the syndrome in which leukocytes may play an important role.
Materials and methods: In this pilot study of six patients with acute warm CRPS I, we performed radiolabeled autologous leukocyte scans of both hands, in order to assess leukocyte accumulation. Comparison was made with the unaffected limb, and with three control patients with a Colles fracture without CRPS I.
Results: Images of the CRPS I patients obtained 4 h after leukocyte injection provided the clearest results. At 4 h post-injection, there was clear, asymmetrical leukocyte accumulation in the affected extremity with a mean ratio of 1.49+/-0.19. In control patients, no asymmetry was observed between hands (mean ratio 1.09+/-0.06), indicating the absence of specific leukocyte accumulation. There was a statistically significant difference between CRPS I and control subjects 4 h post injection (p=0.012).
Conclusion: We found a significantly increased accumulation of leukocytes in patients with CRPS I. This is the first study to show a possible role for leukocytes in the pathophysiology of acute CRPS I.