Influence of botulinum toxin site of injections on healing rate in patients with chronic anal fissure

Background: Botulinum toxin induces healing in patients with idiopathic anal fissure. Methods: Fifty patients affected by posterior anal fissure were treated with 20 units of botulinum toxin, injected in the internal anal sphincter on each side of the posterior midline (group I) or on each side of the anterior midline (group II). Results: At 2 months evaluation, a healing scar was observed in 15 patients of group I and in 22 patients of group II (P = 0.025). Resting anal pressure was significantly different from the baseline values at 1-month as well as at 2-month check-ups in both groups, but the values were significantly lower in patients of group II. Conclusions: The intersite comparison revealed that anterior injection of the internal anal sphincter resulted in improved lowering of resting anal pressure and produced an earlier healing scar.