Surgery, Gastroenterology and Oncology

Background: Intersphincteric resection (ISR) has become a common procedure for lower rectal cancer. However, while the anus can be preserved, thereby avoiding colostomy, anal sphincter dysfunction remains a troublesome complication. This is a serious problem with no effective therapies available at present. We established a novel rat model with long-term anal sphincter dysfunction. The objective of this experiment was to assess anal functional recovery after electrical muscle stimulation (EMS) of the anal sphincter in anal dysfunction model rats.

Methods: Twenty female Sprague-Dawley rats underwent resection of the approximately half of the internal and external anal sphincter. Rats were divided into two groups: one treated by electrical stimulation to anal sphincter (EMS group, n=10), and another with no treatment after surgery (control group, n=10). The EMS group rats had an electrode pad placed at the anus and received electrical stimulation. The rats were then evaluated for the anal function by measuring their resting pressure before surgery and on postoperative days. Additionally, the rats were histologically examined for the asessment of smooth muscle.

Results: The pressure of the anus was not significantly different between the two groups. However, the rate of the improvement of the anal pressure was greater in the EMS group than in the control group (293.4% vs. 129.6%, p<0.005) significantly. Pathologically, the internal sphincter muscle of the bundles of the EMS group became significantly thicker (1.22 times thicker than the external ones, p<0.05).

Conclusion: EMS to the anal sphincter has the therapeutic possibility to resolve anal sphincter dysfunction following anorectal surgery, including ISR.

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