Purpose: Glyceryl trinitrate paste is used by many as first-line therapy for chronic anal fissure but heals only approximately 50 to 60 percent of fissures. We use botulinum toxin as second-line therapy after failed glyceryl trinitrate and aimed to evaluate efficacy, side effects, and patient preference.
Methods: A prospective, nonrandomized, open-label study of patients with chronic anal fissure failing a course of glyceryl trinitrate treated with 20 units of botulinum toxin A injected into the internal sphincter was conducted. Symptomatic relief, visual healing of fissures, side effects, and patient preference were assessed at 8-week follow-up.
Results: Forty patients underwent botulinum toxin treatment. Twenty-nine patients (73 percent) overall were improved symptomatically and avoided surgery. Seventeen fissures (43 percent) were healed, whereas 23 fissures (57 percent) remained unhealed. Of the unhealed fissures, 5 (12 percent) were asymptomatic, 7 (18 percent) were symptomatically much improved, and 11 (27 percent) were no better symptomatically and came to surgery. Discomfort associated with injection was minimal. Of 34 patients undergoing botulinum toxin injection in the clinic, 24 (71 percent) preferred botulinum toxin, 7 glyceryl trinitrate (20 percent; difference = 51 percent; 95 percent confidence interval = 31-71 percent), and 9 percent were undecided. Transient minor incontinence symptoms were noted in 7 patients (18 percent).
Conclusions: Second-line botulinum toxin injection improves symptoms in approximately three-quarters of patients after failed primary glyceryl trinitrate therapy and at least in the short term avoids surgical sphincterotomy. Botulinum toxin heals approximately one-half of these fissures. Discomfort and side effects were minimal. A policy of first-line glyceryl trinitrate/second-line botulinum toxin will avoid sphincterotomy in 85 to 90 percent. Higher rates of healing may be achieved by giving botulinum toxin as first-line therapy, or addressing the chronic fibrotic nature of the fissure.