THE SUCCESSFUL treatment of pruritus ani depends on understanding its cause. In 1936 Hellwig and I1 presented the results of our histological study of 43 cases of pruritus and concluded that this disease is the manifestation of a chemical dermatitis. Since then, almost 100 papers have appeared in the literature, and there is still much controversy concerning the cause of this distressing condition.
The etiological factors which, during the last decade, have been regarded as responsible for pruritus ani can be divided into five groups:1. Nervous disorders often underlie pruritus, according to Drueck (1943),2 and may range from simple instability to true psychosis. Bacon and Smith (1949)3 believe that a disturbance in the sympathetic nervous system may reduce the threshold to the sensation of itching. In five patients with intractable pruritus that had not responded to therapy, these authors obtained immediate relief by a