Is a chronic pain condition that most often affects one limb (arm, leg, hand, or foot) usually after an injury such as a fracture or after surgery. The cause is unknown. it has two subtypes: Type I : -previously called reflex sympathetic dystrophy- refers to CRPS without evidence of a specific peripheral nerve injury. Type II: previously called causalgia- refers to when there is specific evidence of a nerve injury. Symptoms: - Prolonged severe pain that may be constant that is continuous burning or throbbing pain. - Changes in skin texture on the affected area; it may appear shiny and thin and tender. - Abnormal sweating pattern in the affected area or surrounding areas. - Sensitivity to touch or cold. - Swelling of the painful area. - Stiffness in the joints. Treatment: Taking vitamin C after a fracture(wrist) and early mobilization may help to prevent CRPS. The outcome of CRPS is highly variable. with younger people, tending to have better outcomes. While older people can have good outcomes, with some experiencing severe pain and disability. - physical therapy (exercises, contrast bath). - Mirror box therapy. - Psychotherapy. - Medications.