Study of Proteins Associated With Complex Regional Pain Syndrome

This study will try to learn more about complex regional pain syndrome, or CRPS (previously known as reflex sympathetic dystrophy, spreading neuralgia, and sympathalgia), by examining the release of small proteins in the blood of patients with this condition. Patients with CRPS usually have three types of symptoms: * Sensory abnormalities increased sensitivity to pain or a painful reaction to a harmless stimulus * Perfusion abnormalities alterations in blood flow, temperature abnormality, swelling, decrease or increased nail growth, and hair and skin changes * Motor abnormalities weakness, guarding (Holding the limb in such a fashion that it minimizes accidental or intentional contact from possible sources of pain), and atrophy (wasting) The cause of CRPS is unknown, and there are no definitive diagnostic tests for the condition. Because early treatment improves the prognosis of CRPS, a test that enables early diagnosis would be important for optimal medical management. The findings of this study may contribute to the development of such a test and possibly new drug treatments. Normal healthy volunteers and patients of any age with complex regional pain syndrome who are in otherwise good general health may be eligible for this study. Participants will have a medical history, physical examination and collection of a blood sample. They will fill out several questionnaires, providing information on their health, personality, mood, pain levels, and symptoms. Participation in the study requires one outpatient clinic visit.