Comparison of the Effects of Two Different Doses of Botulinum Toxin in the Treatment of Chronic Anal Fissure

Chronic anal fissure is a common disease of the anorectal area. According to manometric studies, the increase of anal sphincter pressure is the most common cause of chronic anal fissure. Therefore, treatment is focused on decreasing the anal sphincter pressure. The injection of botulinum toxin into anal sphincter is one of the treatments, but its ideal dose has not been identified yet. The aim of the study was to compare the effects of the two different doses of toxin on fissure healing rate, and also assessement of the complication of the treatment. 70 patients with history of more than 3 months anal problem, with signs of chronic anal problems, such as skin tag and or visible internal anal sphincter muscle fiber at the base of ulcer were enrolled. 38 patients were men and 32 patients were women. Mean age was 35.3+11.2 years, and average length of illness was 10.29+4.15 months. The results showed 82.85% of patients had posterior anal fissure. The most common symptom was pain with defecation. In each group, four patients were lost from the study and 62 patients completed the study. One of the patients from the low dose group (I) and 4 patients from the high dose group (II) had gas incontinence. After one week, only 4 patients from the high dose group (II) had recovery, but no patient of the low dose group (I) had recovery. After two weeks, 20% of the patients in group I and 50% of the patients in group (II) had recovery. After 8 weeks, 80% of the patients in the group I and 90.6% of group II had recovery (P=0.29). Two patients in group I had rapid recurrence before six months. There wasnt any rapid recurrence in group II. At the end of the study, 22 patients from group I and 29 patients from group II had complete recovery. Six patients from group I and 3 from group II showed no response to the treatment, and most of them had chronic anterior part fissure. Four patients in group I and 2 patients in group II had recurrence after the one year follow-up. It seems that higher�doses of botulinum toxin in-patients with chronic anal fissure increases the treatment response without permanent side effects.