Higher or lower doses of botulinum toxin for the treatment of chronic anal fissure?

Identifying the best therapy for chronic anal fissure

Chronic anal fissure (CAF) is a painful tear or crack which occurs in the anoderm. The optimal algorithm of therapy for CAF is still debated. Lateral internal sphincterotomy (LIS) is a surgical treatment, considered as the ‘gold standard’ therapy for CAF. It relieves CAF symptoms with a high rate of healing. Chemical sphincterotomy (CS) with nitrates, calcium blockers or botulinum toxin (BTX) is safe, with the rapid relief of pain, mild side-effects and no risk of surgery or anesthesia, but is a statistically less effective therapy for CAF than LIS. This article considers if aggressive treatment should only be offered to patients who fail pharmacological sphincterotomy. Aspects of anal fissure etiology, epidemiology and pathophysiology are considered with their meaning for further management of CAF. A molecular model of chemical interdependence significant for the chemistry of CAF healing is examined. Its application may influence the development of optimal therapy for CAF. BTX is currently considered the most effective type of CS and discussion in this article scrutinizes this method specifically. Although the effectiveness of BTX vs. LIS has been discussed, the essential focus of the article concerns identifying the best therapy application for anal fissure. Elements are presented which may help us to predict CAF healing. They provide rationale for the expansion of the CAF therapy algorithm. Ethical and economic factors are also considered in brief. As long as the patient is willing to accept the potential risk of fecal incontinence, we have grounds for the ‘gold standard’ (LIS) as the first-line treatment for CAF. We conclude that, when the diagnosis of the anal fissure is established, CS should be considered for both ethical and economic reasons. The author is convinced that a greater understanding and recognition of benign anal disorders by the GP and a proactive involvement at the point of initial diagnosis would facilitate the consideration of CS at an earlier, more practical stage with improved outcomes for the patient.

Why the most potent toxin may heal anal fissure

An anal fissure is a painful linear ulcer in the lower part of the anal canal. It is very often referred to as an ischemic ulcer. Anodermal blood flow is negatively correlated with resting pressure of the anus. Increased activity of the internal anal sphincter may decrease the anodermal blood supply by compressing arterioles. Surgical procedures and botulinum treatment for patients with chronic anal fissure produce a temporary reduction in anal pressure, reverse sphincter spasm, and promote fissure healing. However, recent studies have shown that fissure healing does not appear to be dependent on reduction in mean resting anal pressure. On the basis of the published literature, this article attempts to explain this phenomenon in detail. The mechanism of action of botulinum toxin on the internal anal sphincter is not yet fully understood. This review focuses on problems associated with anal fissure treatment and presents them from the wider angle of science about botulinum toxin. In our opinion, anodermal blood flow depends not only on the "mechanical" force of sphincters but also on biochemical processes that occur in the fissure region.