Complex regional pain syndrome is thought to involve changes in how the nervous system processes pain after an injury. Signals that should fade as the body heals keep firing, and the affected area can also show changes in blood flow, temperature, sweating and skin appearance.
You may also hear CRPS called reflex sympathetic dystrophy (RSD) or sympathetic pain, older terms that reflect the role of the sympathetic nervous system. There are two types. CRPS I, the most common, occurs without a confirmed nerve injury. CRPS II follows a specific nerve injury.