title: Randomized controlled trial of visualization versus neuromonitoring of the external branch of the superior laryngeal nerve during thyroidectomy.
abstract: BACKGROUND
  Injury to the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy results in a lowered fundamental frequency of the voice and deteriorated voice performance in producing high-frequency sounds. It remains unclear if the use of intraoperative nerve monitoring (IONM) can improve the clinical outcome of thyroidectomy in terms of preserved individual voice performance. This study was designed to test that hypothesis.
  
  
  METHODS
  A total of 210 consenting female patients planned for total thyroidectomy were randomly assigned to two groups equal in size (n = 105): visual inspection of the EBSLN and RLN vs. this plus additional EBSLN and RLN monitoring. The primary outcome was the identification rate of the EBSLN. The secondary outcomes included: anatomical variability of the EBSLN according to the Cernea classification and changes in postoperative voice performance. Voice assessment included pre- and postoperative videostrobolaryngoscopy and an analysis of maximum phonation time (MPT), voice level (VL), fundamental frequency (Fo), and voice quality rating on the GRBAS scale.
  
  
  RESULTS
  The following differences were found for operations without vs. with IONM: identification rate of the EBSLN was 34.3 % vs. 83.8 % (p < 0.001), whereas a 10 % or higher decrease in phonation parameters was found in 10 % vs. 2 % patients for MPT (p = 0.018), 13 % vs. 2 % for VL (p = 0.003), and 9 % vs. 1 % for Fo (p = 0.03), a change in the GRBAS scale > 4 points in 7 % vs. 1 % (p = 0.03), and temporary RLN injury was found in 2 % vs. 1 % (p = 0.56), respectively.
  
  
  CONCLUSIONS
  The use of IONM significantly improved the identification rate of the EBSLN during thyroidectomy, as well as reduced the risk of early phonation changes after thyroidectomy.
authors.affiliation: Department of Endocrine Surgery, 3rd Chair of General Surgery, Jagiellonian University College of Medicine, 37 Prądnicka Street, 31-202 Kraków, Poland. marbar@mp.pl
authors.forename: Marcin
authors.initials: M
authors.lastname: Barczyński
authors.forename: Aleksander
authors.initials: A
authors.lastname: Konturek
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Stopa
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Honowska
authors.forename: Wojciech
authors.initials: W
authors.lastname: Nowak
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006042:Goiter / Q000601:surgery*; D006801:Humans; D061224:Laryngeal Nerve Injuries / Q000209:etiology / Q000517:prevention & control*; D007823:Laryngeal Nerves / Q000033:anatomy & histology / Q000502:physiology; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D013965:Thyroidectomy / Q000009:adverse effects* / Q000379:methods; D014832:Voice Disorders / Q000209:etiology / Q000517:prevention & control*