Complex regional painThe combination of features often associated with an injury or surgery is more common in the arms and legs, especially in the hands or feet and is diagnosed by a combination of signs and symptoms which coexist to form the syndrome.The changes in activity of the affected nerves in the tissues, the changes within the spinal cord nerve processing which seems to involve a type of nerve ‘short-circuit’ , and alterations in the brain’s representation of its image of the injured area or the homunculus, combine to present this group of signs which allow a this diagnosis to be made.Pain felt when the skin is simply stroked or touched is called allodynia and hyperalgesia and is usually a sign of nerve injury. There may be changes in skin colour or swelling of the limb due to autonomic changes especially in the early stages of the condition. Changes in the skin and loss of skin hair may be noticed and in some cases there may be spasm of the muscles close to the injury possibly due to increased activation within the spinal cord known as hypertonicity. Previously this condition in its early phase was known as ‘Reflex Sympathetic Dystrophy’ or RSD typified by pain and autonomic changes now known as CRPS type I. Later more chronic changes were classified as CRPS Type II where pain and sensitivity with muscle and bony changes are seen. Recently however there has been a classification change to allow the inclusion of less ‘typical’ presentations of the condition.