Functional perineal colostomy with pudendal nerve anastomosis following anorectal resection: An experimental study

Abstract

The aim was to reconstruct the functional anus by using a transposed skeletal muscle with pudendal nerve anastomosis (PNA) after anorectal resection. Transposition of the biceps femoris muscle (BFM) with PNA around the perineal colostomy was performed in 22 dogs. In the control group (n = 11) the BFM with its own nerve was used. Evaluation was done at 3 to 5 months after the operation. A contraction with evoked potential on electrical stimulation of the pudendal nerve (22 of 22) and tonic electrical activity (10 of 10) were observed in the dogs with PNA but not in those without PNA. Increased electrical activity (6 of 6) and a reactive rise in the neoanal canal pressure (9 of 13) were seen just after the insertion of a microballoon in the dogs with PNA but not in those without PNA. The neoanal canal length was elongated, and the anorectal angle became acute on electrical stimulation in both groups. No difference was seen in the resting anal pressure between both groups. The pattern of actomyosin adenosine 5'-triphosphatase staining of the neosphincter with PNA converted from that of a BFM to that of the external anal sphincter. The defecatory status in the study group was better according to the evaluation of the feces on the cage floor. Acceptable neoanal function was achieved through the sphincter reconstruction with PNA.