title: 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.
  
  
  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.
authors.affiliation: a Department of General, Visceral and Transplant Surgery , University Medical Center, Johannes Gutenberg-University Mainz , Mainz , Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Kneist
authors.affiliation: a Department of General, Visceral and Transplant Surgery , University Medical Center, Johannes Gutenberg-University Mainz , Mainz , Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Hanke
authors.affiliation: a Department of General, Visceral and Transplant Surgery , University Medical Center, Johannes Gutenberg-University Mainz , Mainz , Germany.
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Kauff
authors.affiliation: a Department of General, Visceral and Transplant Surgery , University Medical Center, Johannes Gutenberg-University Mainz , Mainz , Germany.
authors.forename: Hauke
authors.initials: H
authors.lastname: Lang
mesh_terms: D000328:Adult; D000368:Aged; D001003:Anal Canal / Q000294:innervation*; D015897:Comorbidity; D005260:Female; D006801:Humans; D010535:Laparoscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D012004:Rectal Neoplasms / Q000473:pathology / Q000601:surgery*; D012307:Risk Factors; D012737:Sex Factors; D000067368:Transanal Endoscopic Surgery / Q000379:methods*
keywords: Rectal cancer; TaTME; autonomic nerves; total mesorectal excision; transanal surgery