Ischaemic nature of anal fissure

Abstract

Microvascular perfusion of the anoderm was assessed by laser Doppler flowmetry in 27 patients with anal fissure. Anal pressure was recorded simultaneously. Both measurements were repeated 6 weeks after lateral internal sphincterotomy and compared with those obtained from 27 controls. Means(s.d.) maximum anal resting pressure was significantly higher in those with a fissure than in controls (121.07(24.48) versus 68.78(16.97) mmHg, P < 0.001). Anodermal blood flow at the fissure site was significantly lower than at the posterior commissure of the controls (0.46(0.20) versus 0.76(0.28) V, P < 0.001). The fissure healed in 24 patients within 6 weeks of sphincterotomy. In these patients a significant pressure decrease was noted (35 per cent) which was accompanied by a consistent rise in blood flow (65 per cent) at the original fissure site. The increased internal sphincter tone in patients with a fissure reduces anodermal blood flow at the posterior midline. Reduction of anal pressure by sphincterotomy improves anodermal blood flow at the posterior midline, resulting in fissure healing. These findings provide evidence for the ischaemic nature of anal fissure.

Comparison of Lateral Internal Sphincterotomy with Topical Nitroglycerine Treatment in Patients with Chronic Anal Fissure: A Prospective Randomised Study

“…In a study by Schouten et al [7] of 24 patients with chronic anal fissure who underwent LIS, decrease in anal pressure was observed in 35% of patients while a constant increase was observed in blood circulation in that region in 65% of patients. Traumatic laceration of anoderm is the major triggering factor [7].…”

“…Traumatic laceration of anoderm is the major triggering factor [7]. In patients with previous increase in internal sphincter tonus, the rate of recovery is slow in traumatic lesions of anoderm.…”

“…In patients with previous increase in internal sphincter tonus, the rate of recovery is slow in traumatic lesions of anoderm. Impaired perfusion of anoderm especially in posterior midline results in ischemic ulceration [7]. It has been reported that in elderly and postpartum patients anal fissures are associated with normal and even hypotonic sphincters [8,9].…”

“…It is characterized by persistent hypertonia and IAS spasm. IAS hyper tonicity and relative lack of blood supply in midline caused by it results in the development of an ischemic ulcer and refractory fissure [2][3][4]. The surrounding area of the fissure is raised due to inflammation and scarring.…”

The effect of lateral internal sphincterotomy on resting anal sphincter pressures*

“…Acute or chronic, almost all anal fissures appear on posterior midline (8). The vulnerability of the mucosa in the posterior midline to direct traumas, due to its relative inflexibility and lack of connective tissue support (9), and poor blood flow in the posterior anal wall, which has been demonstrated with Doppler and flowmetry (10)(11)(12), have been suggested for pathogenesis. Crohn's disease, AIDS, lymphoma, leukemic ulceration, epithelial tumors of the anal canal, syphilis, herpes simplex infection, tuberculosis, and cytomegalovirus infection should all be considered in atypical anal canal ulcerations (13).…”