Therapeutic effects of different doses of botulinum toxin in chronic anal fissure.

PURPOSE: The aim of this study was to evaluate the clinical and manometric results of three different doses of botulinum toxin and two methods of injection for the treatment of chronic idiopathic anal fissure.

METHODS: Sixty-nine patients with chronic anal fissure were included in a non-randomized, prospective trial of intrasphincteric injection of botulinum toxin. All patients reported postdefecatory anal pain lasting more than two months. Scoring systems were developed for anal pain, bleeding, and defecatory difficulty. Maximum resting and squeeze anal pressures were determined before and one month after treatment. Twenty-three patients undergoing a 5-U injection of diluted botulinum toxin A (BOTOX) on each side of the anal sphincter (total dose, 10 U) constituted the first group. In a second group 27 patients were injected as previously described, with an additional 5-U injection below the fissure (total dose, 15 U). The 19 patients constituting the third group received a 7-U injection on each side of the anus and below the fissure (total dose, 21 U). All patients were followed up for at least six months.

RESULTS: Pain relief one month after treatment was more evident in the second and the third group (48 percent of patients in the first group, 74 percent in the second group, and 100 percent in the third group). A significant reduction of the mean resting pressure was demonstrated only in Groups II and III (P < 0.05), whereas the mean squeeze pressure significantly decreased in the three groups (P < 0.01 in Group I and P < 0.001 in Groups II and III). Fifty-two percent of the patients in the first group, 30 percent in the second group, and 37 percent in the third group were reinjected during the follow-up period, because of persistence of symptomatology or early relapse. The need for surgery was similar in the first and the second group (17 and 19 percent, respectively) and clearly lower in the last group (5 percent). No serious complications or incontinence attributable to this therapeutic modality developed in any patient.

CONCLUSIONS: Intrasphincteric injection of botulinum toxin is a reliable new option in the treatment of uncomplicated chronic anal fissure. The healing rate is related to the dose and probably to the number of puncture sites. No permanent damage to the continence mechanism was detected in these patients.