ANAL-FISSURE - NEW CONCEPTS IN PATHOGENESIS AND TREATMENT

The posterior commissure of the anal canal is less well perfused than the other segments of the anoderm. There is growing evidence that the increased activity of the internal anal sphincter, which is found in a lmost all patients with a chronic anal fissure, further decreases the anodermal blood supply, especially at the posterior midline. Reduction of anal pressure, either by anal dilatation or by lateral internal sp hincterotomy, is the most important step in the treatment of chronic a nal fissure. However, both procedures frequently result in permanent s phincter defects and subsequent continence disturbances. Recently, nit ric oxide (NO) has been identified as the chemical messenger mediating relaxation of the internal anal sphincter. It has been shown that loc al application of exogenous NO donors such as nitroglycerin and isosor bide-di-nitrate reduces anal pressure and improves anodermal blood flo w. This dual effect results in fissure healing in more than 80% of pat ients.