title: Contribution of intraoperative neural monitoring to preservation of the external branch of the superior laryngeal nerve: a randomized prospective clinical trial.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the effect of intraoperative neuromonitoring (IONM) on the injury rate of the external branch of the superior laryngeal nerve (EBSLN) during thyroidectomy.
  
  
  METHODS
  A total of 133 consenting patients (98 female, 35 male; mean age, 45.6 ± 11.7 years) undergoing thyroidectomy were randomly assigned to 2 groups. In group 1 (n = 65 patients, 105 nerves), superior thyroid pole dissection was performed with no attempt to identify the EBSLN; in group 2 (n = 68 patients, 106 nerves), IONM was used to identify the EBSLN during surgery. EBSLN function was evaluated by intraoperative electromyography of the cricothyroid muscle. The EBSLN Voice Impairment Index-5 (VII-5) was conducted preoperatively and at 1, 3, and 6 months postoperatively. The primary outcome was the prevalence of EBSLN injury. The secondary outcomes were the identification rate of the EBSLN using IONM and changes in postoperative voice performance.
  
  
  RESULTS
  EBSLN injury was detected in eight (12.3%) patients and nine (8.6%) nerves in group 1 and in one (1.5%) patient and one (0.9%) nerve in group 2 (patients, p = 0.015; nerves, p = 0.010). IONM contributed significantly to visual (p < 0.001) and functional (p < 0.001) nerve identification in group 2. The VII-5 indicated more voice changes in group 1 than 2 at 1, 3, and 6 months postoperatively (p = 0.012, p = 0.015, and p = 0.02, respectively).
  
  
  CONCLUSIONS
  IONM contributes to visual and functional identification of the EBSLN and decreases the rate of EBSLN injury during superior pole dissection. Routine use of IONM to identify the EBSLN will minimize the risk of injury during thyroidectomy.
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey. drmuludag@hotmail.com.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Uludag
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Nurcihan
authors.initials: N
authors.lastname: Aygun
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Kinyas
authors.initials: K
authors.lastname: Kartal
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Bulent
authors.initials: B
authors.lastname: Citgez
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Evren
authors.initials: E
authors.lastname: Besler
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Gurkan
authors.initials: G
authors.lastname: Yetkin
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Cemal
authors.initials: C
authors.lastname: Kaya
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Hamdi
authors.initials: H
authors.lastname: Ozsahin
authors.affiliation: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Mihmanli
authors.affiliation: General Surgery, Bahcesehir University Medical Faculty, Istanbul, Turkey.
authors.forename: Adnan
authors.initials: A
authors.lastname: Isgor
mesh_terms: D000328:Adult; D000368:Aged; D004576:Electromyography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D061224:Laryngeal Nerve Injuries / Q000209:etiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D013961:Thyroid Gland / Q000503:physiopathology / Q000601:surgery*; D013965:Thyroidectomy / Q000009:adverse effects* / Q000379:methods*; D016896:Treatment Outcome; D014826:Vocal Cord Paralysis / Q000209:etiology / Q000517:prevention & control*
keywords: Cernea classification; Cricothyroid muscle; EBSLN; EBSLN injury; External branch of the superior laryngeal nerve; Friedman classification; Intraoperative electromyography; Intraoperative neuromonitoring; Nerve identification; Voice change