MECHANISMS OF ENTERIC CONTINENCE IN HEALTH AND DISEASE

肛肠和远端结肠功能紊乱

Disturbances of function of the anorectum and distal colon contribute notably to several important but ill-defined clinical problems, including fecal incontinence, constipation, rectal prolapse, fissure-in-ano, and other perianal problems. A renewed interest in sphincter sparing operations after proctocolectomy has given additional emphasis to the functions of this region. However, a better understanding of these conditions is dependent upon better definition of the region's normal physiology which, in turn, is restricted by current methodologies. Our long-term goals are to develop better techniques, by which to define anorectal physiology, and to utilize these techniques to examine mechanisms of continence and defecation in health, in disease and after operation. The specific aims are: 1) To define precisely the high pressure zone of the anal canal. The technique entails imbedding an array of transducers which are orientated radially, in a flexible probe, and reproducing pressure profiles by computerized dynamic reconstruction. 2) To define accurately the anorectal angle. The technique employs a radiolabelled, fluid- filled balloon, placed through the anal canal. It images scintigraphically, by simultaneous computerized static and dynamic quantification, the anorectal angle and the length, descent and opening pressure of the anal canal. 3) To measure rectal accommodation. The technique entails recording tone of the rectal wall indirectly by measuring changes in volume of an intrarectal balloon maintained at constant pressure by an electronic barostat. 4) To define propulsive forces in the rectum. The technique employs an intrarectal probe constructed such that only forces directed axially, against the tip of the probe, are recorded. 5) To characterize better rectal evacuation. The technique involves instilling artificial radiolabelled stool of varying consistencies and quantifying rectal emptying by static and dynamic scintigraphic imaging. 6) To apply these techniques sequentially a) in health to establish normal physiologic values, b) in defined populations of patients with common anorectal disorders such as incontinence, constipation, prolapse and fissure, c) in defined populations of patients with anorectal manifestations of inflammatory bowel disease, and d) in defined populations of patients after sphincter-sparing operations.