ABSTRACT
Background: Lateral internal sphincterotomy has been accepted as the gold standard for chronic anal fissure. Despite the effectiveness, it carries a risk of fecal incontinence. Non-operative management of chronic anal fissure has been used as alternative treatment. Objectives: Evaluate the efficacy and long-term outcomes of botulinum toxin injection for the treatment of chronic anal fissure. Material and method: A prospective randomized controlled trial was conducted on 40 patients diagnosed with chronic anal fissure who were assigned to undergo either botulinum toxin injection or lateral internal sphincterotomy. Results: The wound-healing rate at 12 weeks and the reduction of post-treatment-resting pressure was significantly better in the sphincterotomy group. Complications and the continence status were not different between the two treatment groups. None of the patients in the sphincterotomy group required additional treatment, while seven patients in the botulinum toxin injection group underwent subsequent sphincterotomy within three years. Conclusion: The long-term result of botulinum toxin injection for chronic anal fissure was inferior to lateral internal sphincterotomy.