Advances in laboratory techniques allow analysis of clinical samples to identify protein or patterns of protein changes associated with a disease state. Patients suffering with CRPS who are currently seen in a pain clinic will be asked to participate in this study. The subjects will complete a brief symptom survey, be examined by a co-investigator to document sensory, temperature and trophic changes, and have a blood sample collected for protein and gene expression (RNA) analysis. Blood samples from age-matched controls will be collected from non-CRPS patients. Fifty patient samples collected from each group will be analyzed and used to teach the diagnostic software and an additional 20 samples (10 controls, 10 CRPS patients) will be used to validate diagnostic accuracy.