RESUMO
Anal fissure is a chronic condition characterized by painful defecation and rectal bleeding. The aim of this study was to compare the injection of botulinum toxin [BT], versus with surgical lateral internal sphincterotomy [LIS]. In this clinical trial, 40 patients enrolled with chronic idiopathic anal fissure [CIAF] and were divided into 2 groups [20 BT group and 20 LIS group]. Both groups were compared according to complications and healing process during one week, following, 2 and 4 months after interventions. There were no statistical significant differences between 2 groups as a viewpoint of duration of disease, pain and other symptoms at the beginning of the study. The rate of healing in the LIS group was greater than the BT group within the first month [16/0], and second month [16/7] [p<0.05], however, there were no significant differences between the two groups in the 4[th] month [17/11] of the study [p>0.05]. In comparison with the BT group, the severity of pain in the LIS group decreased significantly. There were no significant differences between the two groups regarding complications. Healing in the BT group was approximately similar to the LIS; yet it appears to occur slower than LIS. Therefore, according to the results of the study, injection of the BT is recommended within the first step of CIAF treatment. To obtain the maximum healing effects of BT, a minimum period of 4 months is needed