The management of chronic fissure in-ano with botulinum toxin.

Five patients with a chronic fissure in-ano each received an injection of Clostridium botulinum type A toxin into the lower internal anal sphincter. A mean lowering of maximum resting anal pressure by 23.3 (SEM 5.6) cm H2O was achieved within seven days. Maximum voluntary squeeze pressures were not significantly altered. Anal compliance increased in all cases. Healing of the fissure with an apparent reduction in anal sensation occurred in three of the patients and partial resolution of symptoms in the other two. No adverse effects resulted from injections of the toxin. A controlled trial to compare the relative efficacies of botulinum toxin and lateral sphincterotomy is required.