Fifty-six consecutive patients who subsequently underwent ninety-six lumbar sympathectomies were studied prospectively with regard to the development of postoperative pain. Pain after operation was observed in thirty-four extremities by twenty-five of the patients (35 per cent). It began abruptly an average of twelve days after operation and was often accentuated nocturnally. The pain was almost always described as a deep, dull ache and persisted two to three weeks before spontaneously remitting. Postsympathectomy pain of such severity that parenteral narcotics afforded no relief developed in two of these fifty-six patients and in nine additional patients. Treatment with carbamazepine produced dramatic reduction in the intensity of pain in seven of these nine patients within twenty-four hours after the institution of therapy. Two patients were given intravenous diphenylhydantoin and both experienced immediate relief of pain. The mechanisms of the syndrome and of the action of these drugs are uncertain.
