A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation. XV. Chronic anal fissure: a new theory of pathogenesis.

Pathologic changes in chronic anal fissures were studied in 52 patients. In 40 patients, epithelial cells could be identified in the fissure floor superficial to the internal anal sphincter. The cells were rounded, oval, or columnar and were arranged in clumps or pseudoacinar formations. In 10 patients the anorectal sinus was detected in the fissure floor, whereas in 2 patients no epithelial cells could be found. It seems that chronic anal fissure results from disruption of the anal lining, which exposes epithelial cells or the anorectal sinus in the wound floor to repeated infection. It is believed that these epithelial cells are just anorectal sinus remnants that exist in the submucosa of the anal canal proper as epithelial debris or anorectal band. Epithelial cells act as multiple sequestra that harbor the infection and are responsible for fissure chronicity. These patients are predisposed to anal traumatization by feces, owing to the anorectal band's constricting effect on the anal canal proper. The exclusive fissure location in the anal canal proper and not in the rectal neck is due to the anorectal sinus remnants contained therein. The posterior and, rarely, anterior median fissure position is ascribed to the existence of two weak anal areas. The break commonly occurs posteriorly because the posterior anal wall lacks sufficient support. It is concluded that fissure excision, including anorectal bandotomy, at present, is the best treatment to achieve a radical cure.