Background: Botulinum toxin (BT) is a nonsurgical alternative to lateral internal sphincterotomy (LIS). While there are promising results, there is still a gap in knowledge regarding long-term outcomes and the predictors for healing after BT.
Methods: Chronic anal fissure (CAF) patients treated with 100 IU BT with a minimum 5-year follow-up were analyzed retrospectively. Patients with persistent or recurrent fissures after their first BT injection were offered either a second BT injection or LIS. Healing was defined as complete symptom resolution with fissure epithelization. The primary outcome measure was recurrence-free healing rate with BT at 5 years. Predictors of healing were assessed by logistic regression analysis.
Results: The mean age was 33.8 ± 10 years, and 139 (69.5%) patients were female. The complete healing rate at 5 years was 73.8% and 26.2% for the patients that underwent LIS. Multivariate analysis for LIS likelihood revealed that female gender (odds ratio, OR: 0.48, 95% confidence intervals, CI 0.25-0.92, p = 0.028), absence of chronic constipation (OR: 0.09, 95% CI 0.03-0.25, p = < 0.0001), and shorter constipation duration (OR: 1.10, 95% CI 1.06-1.13, p = < 0.0001) were predictors for recurrent-free healing after BT at 5-years. A cutoff value of 10 months of constipation yielded an accuracy of 88% for predicting nonhealing with BT (AUC: 0.881). BT-related incontinence was mild and resolved within 2 months, while LIS resulted in 19.2% permanent incontinence at 5 years.
Conclusions: BT is an effective and safe treatment for CAF, with acceptable long-term outcomes and minimal incontinence risk. Constipation duration and gender are key predictors of healing, aiding patient selection. Male patients with prolonged constipation may benefit from earlier consideration of LIS.
Keywords: Anal fissure; Botulinum toxin; Constipation; Incontinence; Lateral internal sphincterotomy.
© 2025. The Author(s).
