A burning pain often associated with trophic skin changes in the hand or foot, caused by peripheral nerve injury. The syndrome may be aggravated by the slightest stimuli or it may be intensified by the emotions. Causalgia usually begins several weeks after the initial injury and the pain is described as intense, with patients sometimes taking elaborate precautions to avoid any stimulus they know to be capable of causing a flare-up of symptoms. They often will go to great extremes to protect the affected limb and become preoccupied with such protection. Any one of a variety of injuries to the hand, foot, arm, or leg can lead to causalgia, but in most cases there has been some injury to the median or the sciatic nerve. Injections of a local anesthetic at the painful site may bring relief. Sympathectomy may be necessary to eliminate the severe pain, and in the majority of cases it is quite successful. Psychotherapy may be necessary when emotional instability is suspected. Emotional problems may have been present before the initial injury, or they may result from the intense suffering characteristic of severe causalgia.