Botulinum toxin therapy for chronic anal fissures: Where are we at currently?

Background: Botulinum toxin (Botox) injection for chronic anal fissure (CAF) is commonly performed, yet there remains no consensus on optimal dosage or frequency of injections required to achieve complete resolution of anal fissure. The aim of this study was to determine the effectiveness of Botox and side-effect profile in the management of CAF. Methods: A retrospective clinical study of patients between 2010 and 2014 who underwent a Botox injection for CAF at a tertiary centre was performed. The effectiveness of Botox was measured using standardized outcomes including overall healing rate, presence of anal pain, recurrence and need for repeat botulinum injection. Binary outcomes were assessed using logistic regression model. The analysis was performed using Stata version 13 (StataCorp, College Station, TX, USA). Results: One hundred and one patients underwent 126 Botox injections within the study period. The mean first post-operative visit was at 1 month. The overall recurrence rate was 32%. The majority of patients were given 33U. No statistically significant relationship between dose and recurrence was identified. The presence of pain at the first post-operative visit was a predictor of future recurrence (odds ratio 3.92, confidence interval 1.58-9.74, P = 0.003). Conclusion: Botox is an effective strategy for CAF. Low doses can be given with good efficacy as highlighted by our audit and has the potential for great cost saving. The best predictor of recurrence is the presence of pain at the first post-procedure visit.