CRPS is a long-term (chronic) pain condition that can affect any area of the body, but often affects an arm or a leg.
Doctors are not sure what causes CRPS. In some cases, the sympathetic nervous system plays an important role in the pain. Another theory is that CRPS is caused by a triggering of the immune response, which leads to the inflammatory symptoms of redness, warmth, and swelling in the affected area.
CRPS has two forms:
Type 1 is a long-term (chronic) nerve disorder that occurs most often in the arms or legs after a minor injury.
Type 2 is caused by an injury to a nerve.