Also known as complex regional pain syndrome (CRPS) — formerly reflex sympathetic dystrophy (RSD), "causalgia," or reflex neurovascular dystrophy (RND) — Sudeck's atrophy is an amplified musculoskeletal pain syndrome (AMPS).
It is a chronic systemic disease characterized by severe pain, swelling, and changes in the skin. CRPS often worsens over time. It may initially affect an arm or leg and spread throughout the body; 35% of people report symptoms throughout their whole body.

The cause of CRPS is unknown, though CRPS is associated with dysregulation of the central nervous system and autonomic nervous system, resulting in multiple functional loss, impairment, and disability. Precipitating factors include injury and surgery, although there are documented cases where no injury had occurred at the original site.
CRPS is not caused by psychological factors, yet the constant pain and reduced quality of life has been known to cause psychological problems (depression, anxiety, impaired social and occupational function).
Treatment is complicated, involving medications, physical and occupational therapy, psychological treatments, and neuromodulation, and is often unsatisfactory, especially if delayed.

See reference for details.

Adapted from Wikipedia, the free encyclopedia. Internet. Accessed on June 14, 2016.