title: Evaluation of type II thyroplasty on phonatory physiology in an excised canine larynx model.
abstract: Type II thyroplasty is an alternative treatment for spasmodic dysphonia, addressing hyperadduction by incising and lateralizing the thyroid cartilage. We quantified the effect of lateralization width on phonatory physiology using excised canine larynges.
  
  
  
  Normal closure, hyperadduction, and type II thyroplasty (lateralized up to 5 mm at 1-mm increments with hyperadducted arytenoids) were simulated in excised larynges (N = 7). Aerodynamic, acoustic, and videokymographic data were recorded at three subglottal pressures relative to phonation threshold pressure (PTP). One-way repeated measures analysis of variance assessed effect of condition on aerodynamic parameters. Random intercepts linear mixed effects models assessed effects of condition and subglottal pressure on acoustic and videokymographic parameters.
  
  
  
  PTP differed across conditions (P < .001). Condition affected percent shimmer (P < .005) but not percent jitter. Both pressure (P < .03) and condition (P < .001) affected fundamental frequency. Pressure affected vibratory amplitude (P < .05) and intrafold phase difference (P < .05). Condition affected phase difference between the vocal folds (P < .001).
  
  
  
  Hyperadduction increased PTP and worsened perturbation compared to normal, with near normal physiology restored with 1-mm lateralization. Further lateralization deteriorated voice quality and increased PTP. Acoustic and videokymographic results indicate that normal physiologic relationships between subglottal pressure and vibration are preserved at optimal lateralization width, but then degrade with further lateralization. The 1-mm optimal width observed here is due to the small canine larynx size. Future human trials would likely demonstrate a greater optimal width, with patient-specific value potentially determined based on larynx size and symptom severity.
  
  
  
  NA Laryngoscope, 2016 127:396-404, 2017.
authors.affiliation: Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin, U.S.A.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Devine
authors.affiliation: Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin, U.S.A.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hoffman
authors.affiliation: Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin, U.S.A.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: McCulloch
authors.affiliation: Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, Wisconsin, U.S.A.
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Jiang
mesh_terms: D000162:Acoustics; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D055154:Dysphonia / Q000503:physiopathology / Q000601:surgery*; D066298:In Vitro Techniques; D007734:Kymography; D058753:Laryngoplasty / Q000379:methods*; D007830:Larynx / Q000502:physiology*; D010699:Phonation / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013957:Thyroid Cartilage / Q000503:physiopathology / Q000601:surgery; D014741:Video Recording; D014827:Vocal Cords / Q000503:physiopathology
keywords: Type II thyroplasty; excised canine model; laryngeal framework surgery; laryngology; vocal folds