Complex regional pain syndrome (CRPS) is a stronger than normal reaction of the body to an injury. The cause of CRPS is not known, but there is ongoing research to understand it better. The nerves in the affected limb become much more sensitive than other nerves and this causes pain and tenderness in the affected area. The brain is also involved. The way the brain communicates with your affected arm or leg changes.
This is a companion discussion topic for the original article at https://patient.info/brain-nerves/complex-regional-pain-syndrome-leaflet