Complex Regional Pain Syndrome (CRPS) is a medical condition that causes excess and prolonged pain and inflammation that can occur following an injury or other medical condition. It is a form of chronic pain that usually affects an arm or a leg and typically develops after an injury, surgery, or trauma. CRPS has two types, with similar signs and symptoms, but different causes. Type 1, also known as reflex sympathetic dystrophy (RSD), occurs after an illness or injury that didnt directly damage the nerves in the affected limb. Type 2, also known as causalgia, occurs after a specific nerve injury.

The symptoms of CRPS may change over time and vary from person to person. Pain, swelling, redness, noticeable changes in temperature, and hypersensitivity (particularly to cold and touch) usually occur first. Over time, the affected limb can become cold and pale. It may undergo skin and nail changes as well as muscle spasms and tightening. Once these changes occur, the condition is often irreversible.

The cause of CRPS is not completely understood, but experts believe that it occurs as a result of dysfunction in the central or peripheral nervous systems. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system relays information from the brain and spinal cord to the organs, arms, legs, fingers, and toes. The abnormal functioning results in an overreaction to pain signals that the nervous system can’t shut off.

There is no specific test to diagnose CRPS. Healthcare providers mainly diagnose it through a careful medical history, physical examination, and review of symptoms. Specific tests can help provide clues, including a bone scan to detect any changes, and tests that measure differences in skin temperature, blood flow, and sweating between affected and unaffected limbs.

Treatment for CRPS is most effective when started early and focuses on managing the symptoms. There are four main types of treatment: education and self-management, physical rehabilitation, pain relief, and psychological support. Because of the complex nature of CRPS, a number of different healthcare professionals will usually be involved in the treatment.