Complex regional pain syndrome (CRPS), also called reflex sympathetic dystrophy syndrome, is a chronic pain condition in which high levels of nerve impulses are sent to an affected site. Experts believe that CRPS occurs as a result of dysfunction in the central or peripheral nervous systems. CRPS is most common in people ages 20-35. The syndrome also can occur in children; it affects women more often than men. There is no cure for CRPS.

What Causes Complex Regional Pain Syndrome? CRPS most likely does not have a single cause; rather, it results from multiple causes that produce similar symptoms. Some theories suggest that pain receptors in the affected part of the body become responsive to catecholamines, a group of nervous system messengers. In cases of injury-related CRPS, the syndrome may be caused by a triggering of the immune response, which may lead to the inflammatory symptoms of redness, warmth, and swelling in the affected area. For this reason, it is believed that CRPS may represent a disruption of the healing process.