Partial lateral internal sphincterotomy versus combined botulinum toxin A injection and topical diltiazem in the treatment of chronic anal fissure: a randomized clinical trial.

The aim of this study is to evaluate the effectiveness and complications associated with combined topical diltiazem cream and botulinum toxin A injection versus partial lateral internal sphincterotomy in chronic anal fissure. This study is a parallel, randomized controlled trial (using the block randomization method). This study was performed at a university hospital in Iran. Ninety-nine patients who had chronic anal fissures were included. A total of 99 patients were randomly assigned to 2 groups; the first group received combined topical diltiazem ointment (for 6 weeks) and botulinum toxin A injection (once) (n = 49), and the second group received partial lateral internal sphincterotomy (n = 50). All the patients were followed up for 1 year. The primary outcomes measured were the healing of the anal fissure and the development of incontinence as the major adverse event during the 1-year follow-up period. The overall healing rate was 65% and 94% in the botulinum toxin A-diltiazem and partial lateral internal sphincterotomy groups (p < 0.001). The patients in the partial lateral internal sphincterotomy group experienced significantly higher incontinence scores (p = 0.04) according to the Cleveland Clinic Florida-Fecal Incontinence scoring system. In patients who had chronic anal fissure for ≤12 months, no statistical difference was observed in the healing rate between the botulinum toxin A-diltiazem and partial lateral internal sphincterotomy groups (100% vs 100%). However, in the patients with longer chronic fissures, the healing rate was significantly higher in the partial lateral internal sphincterotomy group (86% [18/21] vs 23% [5/21], p < 0.001). The 1-year follow-up period, subjective definitions of itching, and lack of anorectal manometry examinations and data regarding the effect of each treatment on anal sphincter pressure at rest and contraction are the key limitations of this study. Combined botulinum toxin A injection with a topical application of diltiazem could be as effective as partial lateral internal sphincterotomy in the treatment of chronic anal fissure in patients who have chronic anal fissure for ≤12 months. However, in chronic anal fissures of longer duration, partial lateral internal sphincterotomy is associated with a significantly higher cure rate.