title: Differentiating arytenoid dislocation and recurrent laryngeal nerve paralysis by arytenoid movement in laryngoscopic video.
abstract: OBJECTIVE
  To present a new method of quantifying arytenoid movement during inspiration and determine if it can be used to distinguish arytenoid dislocation from vocal fold paralysis.
  
  
  METHODS
  Case series with chart review.
  
  
  METHODS
  Retrospective study conducted in a university laboratory based on university hospital data.
  
  
  METHODS
  Endoscopic videos from 8 patients with dislocation and 5 patients with vocal fold paralysis diagnosed by electromyography were included. Vector analysis measured cuneiform movement, an indirect measurement of arytenoid movement, during 1 inspiration. Measurements normalized and not normalized to vocal fold length were evaluated. Interrater reliability (2 raters) and intrarater reliability (1 rater performing the analysis twice) were evaluated using intraclass correlation coefficient (ICC) analysis. Raters were blinded to subject group during analysis.
  
  
  RESULTS
  Pixel-valued cuneiform movement was 81.16 ± 25.62 for dislocation and 30.22 ± 23.60 for paralysis (P = .019). Unitless cuneiform movement was 0.58 ± 0.17 for dislocation and 0.24 ± 0.18 for paralysis (P = .030). Interrater ICC was 0.942 for pixel-valued measurements and 0.962 for unitless measurements. Intrarater ICC was 0.909 for pixel-valued measurements and 0.881 for unitless measurements.
  
  
  CONCLUSIONS
  Both pixel-valued and unitless measures of arytenoid movement were significantly greater in arytenoid dislocation than vocal fold paralysis. Pixel-valued measurements were included to demonstrate the ability to make quantitative comparisons across subjects without precise knowledge of camera precision, provided position is approximately stable, as each measurement is inherently normalized by vocal tract length. Future studies will apply this new method of evaluating vocal fold immobility disorders on a larger scale and incorporate a more diverse group of etiologies.
authors.affiliation: Xiamen University Zhongshan Hospital, ENT Department, Xiamen, Fujian, China.
authors.forename: Peiyun
authors.initials: P
authors.lastname: Zhuang
authors.forename: Steven
authors.initials: S
authors.lastname: Nemcek
authors.forename: Ketan
authors.initials: K
authors.lastname: Surender
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hoffman
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: William J
authors.initials: WJ
authors.lastname: Chapin
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Jiang
mesh_terms: D000328:Adult; D001193:Arytenoid Cartilage / Q000293:injuries*; D003937:Diagnosis, Differential; D004576:Electromyography; D005260:Female; D006801:Humans; D001239:Inhalation; D004204:Joint Dislocations / Q000175:diagnosis*; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D012009:Recurrent Laryngeal Nerve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014741:Video Recording
keywords: arytenoid dislocation; endoscopy; videolaryngoscopy; vocal fold paralysis