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. Another name for complex regional pain syndrome is reflex sympathetic dystrophy.

Skin sensitivity, excessive sweating, numbness, and tingling may also occur with complex regional pain syndrome. This condition is not understood well. And it is difficult to diagnose and treat.