I have had two nerve blocks for chronic pain in my leg called complex regional pain syndrome. They didn't work. Why not?

Until recently, doctors thought that Complex Regional Pain Syndrome (CRPS) was caused by a problem in the sympathetic nervous system (SNS). The SNS is a set of nerves that control the size of blood vessels, sweating, and other body functions.

If it was always caused by the SNS, then the nerve blocks should always work. Since they don't doctors now think only some patient have pain that comes from the SNS. The only way to know for sure is to try the nerve blocks, so it wasn't wasted time or treatment on your behalf.

If a damaged SNS isn't the problem, then what is the cause of the CRPS? Experts agree that there are problems somewhere in the nervous system. Perhaps the central nervous system (the brain and spinal cord). No one is sure just yet.

There are other factors that affect the nervous system like emotional stress. There is some evidence that certain personality types are more prone to CRPS.