title: The importance of sonographic landmarks by transcutaneous laryngeal ultrasonography in post-thyroidectomy vocal cord assessment.
abstract: BACKGROUND
  During examination of the vocal cords (VC) using transcutaneous laryngeal ultrasonography (TLUSG), 3 sonographic landmarks (namely, false VC [FC], true VC [TC], and arytenoids [AR]) are often seen. However, it remains unclear which landmark provides a more reliable assessment and whether seeing more landmarks improves the diagnostic accuracy and reliability.
  
  
  METHODS
  We evaluated prospectively 245 patients from 2 centers. One assessor from each center performed all TLUSG examinations and their findings were validated by direct laryngoscopy. All 3 sonographic landmarks were routinely visualized whenever possible. The rate of visualization and diagnostic accuracy between the 3 landmarks were compared.
  
  
  RESULTS
  Eighteen patients suffered postoperative VC palsy (VCP). Both centers had comparable visualization or assessability rate of ≥ 1 sonographic landmark (94.9 and 95.3%; P = 1.000) and 100% sensitivity on postoperative TLUSG. The rates of FC, TC, and AR visualization were 92.7%, 36.7%, and 89.8%, respectively. The sensitivity, specificity, and diagnostic accuracy and the proportion of true positives, false positives, and true negatives between using 1, 2, landmarks and 3 landmarks were comparable (P > .05).
  
  
  CONCLUSIONS
  Each sonographic landmark had similar reliability and diagnostic accuracy. Identifying all 3 sonographic landmarks was not mandatory and visualizing normal movement in one of the sonographic landmarks would be sufficient to exclude VCP.
authors.affiliation: Department of Surgery, University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Kai-Pun
authors.initials: KP
authors.lastname: Wong
authors.affiliation: Department of Surgery, Seoul National University Hospital and College of Medicine, Seoul, Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jung-Woo
authors.initials: JW
authors.lastname: Woo
authors.affiliation: Department of Surgery, Seoul National University Hospital and College of Medicine, Seoul, Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yeo-Kyu
authors.initials: YK
authors.lastname: Youn
authors.affiliation: Department of Surgery, University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China.
authors.forename: Felix Che-Lok
authors.initials: FC
authors.lastname: Chow
authors.affiliation: Department of Surgery, Seoul National University Hospital and College of Medicine, Seoul, Korea; Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Kyu Eun
authors.initials: KE
authors.lastname: Lee
authors.affiliation: Department of Surgery, University of Hong Kong, Queen Mary Hospital, Hong Kong SAR, China. Electronic address: blang@hkucc.hku.hk.
authors.forename: Brian Hung-Hin
authors.initials: BH
authors.lastname: Lang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059925:Anatomic Landmarks; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007828:Laryngoscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011182:Postoperative Care / Q000379:methods; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013965:Thyroidectomy / Q000009:adverse effects / Q000379:methods*; D018608:Ultrasonography, Doppler / Q000379:methods*; D014826:Vocal Cord Paralysis / Q000000981:diagnostic imaging / Q000209:etiology; D014827:Vocal Cords / Q000000981:diagnostic imaging* / Q000502:physiology; D055815:Young Adult