Botulinum toxin for recurrent anal fissure following lateral internal sphincterotomy.

Background: The aim of the study was to evaluate the efficacy of botulinum toxin injection in the treatment of recurrent anal fissure following lateral internal sphincterotomy.

Methods: Eighty patients were treated with botulinum toxin (30 units Botox or 90 units Dysport), injected into two sites of the internal sphincter. Clinical and manometric results were recorded before and after treatment. If symptoms persisted at 2 months, the examiners could decide to re-treat the patient. The same preparation of serotype A of botulinum neurotoxin was used for reinjection.

Results: One month after injection there was complete healing in 54 patients (68 per cent). Eight patients (10 per cent) reported mild incontinence of flatus that had disappeared spontaneously within 2 months. At 2 months, 59 patients (74 per cent) had a healing scar. After reinjection, 11 of 21 re-treated patients reported mild incontinence to flatus that lasted for a few weeks and resolved spontaneously. Anorectal manometry at 1 month demonstrated a significant reduction in both resting anal pressure and maximum voluntary squeeze pressure (P < 0.001). There were no relapses during a mean value of 57.9 months of follow-up.

Conclusion: Botulinum toxin is efficacious in patients with recurrent anal fissure following lateral internal sphincterotomy.