Complex regional pain syndrome (CRPS), formerly Reflex Sympathetic Dystrophy or Causalgia, is a chronic progressive disease characterized by severe pain, swelling, and changes in the skin. It often affects an arm or a leg and may spread to another part of the body and is associated with dysregulation of the autonomic nervous system resulting in multiple functional loss, impairment, and disability. Though treatment is often unsatisfactory, early multimodal therapy can cause dramatic improvement or remission of the syndrome in some patients. The International Association for the Study of Pain has proposed dividing CRPS into two types based on the presence of nerve lesion following the injury.
