When suspecting a diagnosis of complex regional pain syndrome (or reflex sympathetic dystrophy), what workup should be done to confirm or exclude it?

Every evaluation begins with a thorough history and physical, particularly to look for other explanations of pain to this region. In my opinion, unilateral symptoms are much easier to assess than bilateral symptoms. Bilateral CRPS is reported but it is quite unusual. I am more likely to support a diagnosis of CRPS when there is well-defined trauma to the region, such as a wrist fracture, as this is a classical presentation of post-traumatic pain and swelling in a limb or region. The associated history of diabetes is also quite helpful since the shoulder-hand syndrome is another classical setting for CRPS.

I like having laboratories for this; in particular, ESR and CRP elevations raise concerns for an atypical presentation of an infection which would prompt different treatment. Radiographs on presentation are helpful when positive, but if it is an early case of CRPS, there will be little to see. I do order 3-phase bone scans to look at early and late blood flow to the region since this is the most classical imaging presentation (see this article ). Some information can be obtained with an MRI as well and is frequently useful in more difficult cases (Schürmann et al, Imaging in Early Posttraumatic Complex Regional Pain Syndrome: A Comparison of Diagnostic Methods, The Clinical Journal of Pain, 2007). In the final analysis, it is most important to remember that this does remain a clinical diagnosis, and imaging, while supportive and at times very reassuring, is more helpful in assuring there is not another process occurring in the painful limb than it is "diagnostic" of this disorder.