Comparison of Injections of Botulinum Toxin and Topical Nitroglycerin Ointment for the Treatment of Chronic Anal Fissure

Inclusion Criteria: * Clinical diagnosis: evidence of posterior circumscribed ulcer, with a large sentinel tag of skin, induration at the edges, and exposure of the horizontal fibers of the internal anal sphincter * symptoms (post-defecatory or nocturnal pain, bleeding, or both) lasting for more than two months. Exclusion Criteria: * Patients with acute fissure * fissure associated with other conditions (i.e., inflammatory bowel diseases, HIV infection, hemorrhoids, fistula in ano, anal abscesses, or anal or perianal cancer) * those who had undergone previous surgical procedures in the anal canal. * known hypersensitivity to component of the formulations of type A BTX * pregnant or breast-feeding women 6-refusal of consent