Botulinum toxin injection is an effective alternative for the treatment of chronic anal fissure.

Objectives There are few published data on the optimized use of botulinum toxin A (BTA) for the treatment of chronic anal fissure (CAF). The aim of this study was to investigate the effect of injection of 100 IU botulinum toxin A into the internal anal sphincter at the side opposite of the fissure, using an anal retractor, sedation, and perianal transcutaneous pudendal nerve block. Methods The prospectively maintained data of 132 patients who underwent BTA injection for CAF were retrospectively analyzed. Demographic data, symptom duration, fissure location, post-procedure pain, complications, continence status, response to treatment, and follow-up period were investigated. Postoperative analgesic requirements of patients who did and did not receive pudendal nerve block were compared. Results Eighty two patients were male and the median age was 40 (18-74) years. Sixty-six patients required no, 46 required oral, and 20 required parenteral analgesics. No complications were observed. Complete response was observed in 105 patients (79.5%). Symptomatic improvement was observed in 67.4% of patients within 3-7 days. Median follow-up was 24 (18-42) months. The median Wexner's incontinence score was 0 (0-8) at 1 month. In all, 104 patients had no, 22 patients had minor, and 6 patients had non-minor incontinence. All patients with incontinence recovered fully within 4 (2-13) weeks. Conclusions BTA injection using an anal retractor under sedation and perianal transcutaneous pudendal nerve block is an effective and safe alternative to partial lateral internal sphincterotomy for the treatment of CAF.