Is chemodenervation with incobotulinumtoxinA an alternative to invasive chronic anal fissure treatments?

Background: Botulinum toxin type A is currently strongly recommended for the treatment of anal fissures (AFs). However, there is still no consensus on dosage or injection technique. This study provides further efficacy and safety evidence in a 2-year follow-up.

Method: Prospective, open-label, single-arm, single-center study carried out in adult patients with AFs non-responsive to previous treatments. Patients were treated with incobotulinumtoxinA (incoBoNT/A) injected in both laterals and posterior intersphincteric groove. Healing rate at 2 years was the primary endpoint. Secondary endpoints included internal anal sphincter pressures, incontinence, and safety.

Results: A total of 49 patients were treated with a mean incoBoNT/A dose of 40.5 U (spread across three locations). Healing rate at 2 years was 83.9% with a 24.5% of recurrence throughout the study. Only 7 patients (14.3%) reported adverse events (AEs) that were mild and temporary. Mean reduction in anal resting pressure was -9.1 mmHg at 3 months (p = 0.001). Mean reduction in voluntary squeeze pressure was -27.5 mmHg at 3 months (p < 0.001). Mean pain perception measured with a visual analog scale decreased by -6.5 points at 2 years (p < 0.001). There was an incontinence increase at 1 month of 1.3 points (p = 0.006), but baseline values were restored at 6 months.

Conclusion: We present results that support the use of incoBoNT/A as a second line for AFs that do not respond to ointment therapy. IncoBoNT/A injection is a less invasive treatment that should be considered before surgery due to its efficacy and its safety which includes no permanent impairment.

Trial registration: ISRCTN90354265; Registered on 16th February 2024. Retrospectively registered.