There are many theories about what causes both types of CRPS but nothing has yet been proven. For Type I, the new school of thought is that pain receptors are somehow affected and respond to a family of nervous system messengers called catecholamines. What doctors do know is that 90 percent of people with CRPS had suffered some sort of trauma that could have been minor, like a sprained ankle, or major, like surgery.

Doctors are just as mystified over the causes of CRPS Type II. New theories aim towards that there is some sort of immune response and the body is reacting by causing swelling and pain.