Complex regional pain syndrome, called CRPS, is a disorder that can cause severe pain and disability. However, as painful and disabling as the condition is, there is not a lot that doctors know about it. They do know that more women get it than men and that occurs after about one to two percent of fractures and after up to 35 percent of certain types of wrist fractures. What they don’t know is why it happens, who it will happen to, and how severe it will be. And, because treatment of CRPS depends on the symptoms, doctors often can’t tell you what may work and what may not.