What is complex regional pain syndrome (CRPS)?

Complex Regional Pain Syndrome Type I (CRPS I) is also known as Reflex Sympathetic Dystrophy (RSD) and Complex Regional Pain Syndrome Type II (CRPS II) is also known as Causalgia.

The pain usually develops after an injury to an arm or leg. Only rarely are other areas affected. CRPS I follows an injury to a limb such as a broken bone or even a minor sprain and CRPS II follows partial damage to a nerve in the limb. The symptoms are very similar. However, CRPS II is very rare. ¨ The main symptom is pain in the arm or leg. The pain is often burning, sharp, stabbing or stinging, with tingling and numbness. In addition there is a range of other symptoms which can vary and change over time. Increased skin sensitivity (allodynia), increased sensitivity to pain (hyperalgesia), skin discolouration, swelling, stiffness, feelings of hot or cold, excessive or reduced sweating and changes to the hair, skin or nails. The pain and other symptoms usually spread beyond the site of the original injury.

Pain continues long after the original injury has healed. It is often severe and may get progressively worse. In mild cases the pain can last for weeks or months but in severe cases, when the limb is not used, it can last for years.

The skin may become over sensitive to light touch. Clothes brushing the skin, or a slight draught on the skin, is felt as severe pain. This is called allodynia and is common in CRPS.

Often there is difficulty moving the limb, together with weakness and sometimes tremors or jerking. In severe cases the limb can be fixed in one position.

In very severe cases there may be bone softening resulting in breaks. This is called osteopaenia. There can also be muscle atrophy (wasting) and in extreme cases muscle contracture.

CRPS is a stronger than normal reaction of the body to an injury. The cause of CRPS is not known. The nerves in the affected limb are 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.

The pain usually starts after an injury but may occur without an injury. It usually affects an arm or a leg but can affect another part of the body. The injury may be severe, such as a broken bone or a damaged nerve, or may be a minor injury.

CRPS is not in your imagination or in your mind. However, some emotional factors, like fear, worry or feeling depressed, can make the pain worse than it already is.