Reflex sympathetic dystrophy, also called complex regional pain syndrome, is an unusual neurological disease in which the nervous system malfunctions after a traumatic event, such as an accident, a fall, surgery, or even after a minor injury such as a sprain. This malfunction causes pain that may seem severe compared to the original injury and may remain long after the injury has healed.

Skin sensitivity, excessive sweating, numbness, and tingling may also occur with reflex sympathetic dystrophy. This condition is not understood well and is difficult to diagnose and treat.