Complex Regional Pain Syndrome Type 1 (Reflex Sympathetic Dystrophy) Workup

Updated: Mar 09, 2021
  • Author: T P Sudha Rao, MD; Chief Editor: Herbert S Diamond, MD  more...
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Laboratory Studies

Laboratory studies are not useful for the diagnosis of complex regional pain syndrome (CRPS). Levels of acute-phase reactants (ie, erythrocyte sedimentation rate [ESR], C-reactive protein) are generally within the reference range.



Plain radiographs usually demonstrate pronounced demineralization in the underlying bony skeleton of the involved extremity (ie, Sudeck atrophy) that may become more severe with disease progression. No joint erosions are present. Demineralization begins at the ends of the bones and progresses to become homogeneous.


Radionuclide Imaging

Findings on three-phase radionuclide bone scans are positive in 50-90% of patients with CRPS, and this study is most useful in early disease. Findings on the delayed image (ie, third phase) are generally abnormal, with increased uptake in the articular and periarticular structures of the involved extremity. Of course, this finding is not specific for CRPS) but is supportive of that diagnosis in the appropriate clinical situation. In chronic CRPS, the bone scan findings may be normal, but the plain radiographs generally reveal profound demineralization of the affected extremity. For more information, see Reflex Sympathetic Dystrophy Imaging.