Complex regional pain syndrome (CRPS) is a chronic pain condition most often affecting one of the limbs (arms, legs, hands, or feet). It usually occurs after an injury or trauma to that limb, and is believed to be caused by damage to the peripheral and central nervous systems. CRPS is characterized by prolonged or excessive pain and changes in skin color, temperature, and swelling in the affected area. These symptoms vary in severity and duration. Most cases are mild and individuals recover gradually with time. In more severe cases, individuals may not recover and may have long-term disability. The pain may feel like a burning, “pins and needles” sensation, or as if someone is squeezing the affected limb. The pain may spread to include the entire arm or leg, even though the precipitating injury might have been only to a finger or toe. Pain can sometimes even travel to the opposite extremity. There is often increased sensitivity in the affected area, such that even light touch or contact is painful. Other common features of CRPS include changes in skin texture, nail and hair growth patterns, abnormal sweating pattern, stiffness in affected joints, decreased ability to move the affected body part, fixed abnormal posture, and tremors in or jerking of the affected limb.