Diagnosis of chronic anal fissure is easy and common in clinical practice. Little is known about the etiology and pathogenesis of this disorder. Current investigations consider anal sphincteric hypertonia and ischemia as primary factors in the appearance and maintenance of this lesion. Recurrence rate after healing is high, so anal fissure may be a chronic disease that evolves depending on sphincteric features. Conservative measures to avoid constipation, including fiber intake, are useful to improve symptomatology, achieve healing, and reduce recurrence. Surgical treatment is the most effective procedure for chronic anal fissure. Lateral internal sphincterotomy achieves healing in most cases (more than 95%) and the recurrence rate is low (1% to 3%). However, permanent fecal incontinence may appear after surgery and available data about this complication are controversial. In recent years, chemical sphincterotomy has been developed as an option in the treatment of chronic anal fissure. This medical option aims to achieve the effectiveness of surgery without side effects, by means of a temporary decrease of anal pressures that allows fissures to heal. Local injection of botulinum toxin into the anal sphincter is the most successful medical option, nearly as effective as surgery and without significant adverse effects (transitory episodes of mild fecal incontinence). Although more studies are needed to establish the method of administering this treatment, in our opinion botulinum toxin is an effective option in a high percentage of cases, especially in patients who risk developing incontinence. Compared with botulinum toxin, topical nitroglycerine ointments, which produce a transitory sphincteric relaxation, have the advantage of being a simple and accessible procedure. However, we think that this option should not be a first choice because its effectiveness is lower compared with surgery (about 60% to 70%), its compliance with the application could be poor, and it has a greater percentage of side effects (eg, headache). Other topical treatments (eg, calcium channel antagonist or cholinergic agonists agents) appear to be as effective as nitroglycerine agents and do not have significant adverse effects, but little data exist about these options. In our opinion, treatment of chronic anal fissure must be individualized, depending on the clinical profile of patients. Medical treatment, especially injection of botulinum toxin, should be taken into account if risk for developing incontinence is suspected.
