Surgeons’ assessment of internal anal sphincter nerve supply during TaTME - inbetween expectations and reality

Abstract

Background: Intraoperative identification of nerve fibers heading from the inferior rectal plexus (IRP) to the internal anal sphincter (IAS) is challenging. The transanal total mesorectal excision (TaTME) is said to better preserve pelvic autonomic nerves. The aim of this study was to investigate the nerve identification rates during TaTME by transanal visual and electrophysiological assessment.

Material and methods: A total of 52 patients underwent TaTME for malignant conditions. The IRP with its posterior branches to the IAS and the pelvic splanchnic nerves (PSN) were visually assessed in 20 patients (v-TaTME). Electrophysiological nerve identification was performed in 32 patients using electric stimulation under processed electromyography of IAS (e-TaTME).

Results: The indication profile for TaTME was comparable between the v-TaTME and the e-TaTME group. The identification of IRP was more meaningful under electrophysiological assessment than under visual assessment for the left pelvic side (81% vs. 45%, p = 0.008) as well as the right pelvic side (78% vs. 45%, p = 0.016). The identification rates for PSN did not significantly differ between both groups, respectively (81% vs. 75%, p = 0.420 and 84% vs. 70%, p = 0.187).

Conclusions: The transanal approach facilitated visual identification of IAS nerve supply. In combination with electrophysiological nerve assessment the identification rate almost doubled. For further insights functional data are needed.

Keywords:

• Rectal cancer
• total mesorectal excision
• transanal surgery
• TaTME
• autonomic nerves

Disclosure statement

Werner Kneist, Laura Hanke, Daniel W. Kauff and Hauke Lang report no financial interests or potential conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Ethical approval

This research was performed following the Declaration of Helsinki guidelines. Informed consent was obtained from all individual participants included in the study. Patient information was collected prospectively and entered into an international registry database for TaTME (LOREC Low Rectal Cancer Development Program, www.lorec.nhs.uk) with approval by the local board of ethics (Rhineland Palatinate, Germany).