Complex regional pain syndrome (CRPS), formerly known as Regional Sympathetic Dystrophy (RSD), is an uncommon, chronic condition that affects the nervous system that usually affects your extremities. The cause of CRPS isn't clearly understood, though it often follows an illness or injury.
CRPS is usually presents as an intense burning or aching pain. Patients with CRPS may also experience swelling, skin discoloration, altered temperature, abnormal sweating, hypersensitivity, changes in hair & nail growth patterns, muscle spasms, weakness and decreased ability to move the affected body part.
Symptoms may change over time and vary from person to person. Once these changes occur, the condition is often irreversible. This is why it is important to treat complex regional pain syndrome. In such cases, dramatic improvements may be possible.