title: Phonatory effects of type I thyroplasty implant shape and depth of medialization in unilateral vocal fold paralysis.
abstract: OBJECTIVE
  Medialization thyroplasty (MT) is commonly used to treat glottic insufficiency. In this study, we investigated the phonatory effects of MT implant medialization depth and medial surface shape.
  
  
  METHODS
  Recurrent laryngeal nerve (RLN) and vagal paralysis were simulated in an in vivo canine. A type 1 MT was performed using a silicone elastomer implant with variable medialization depths and medial surface shapes: rectangular, V-shaped, divergent, and convergent. The effects on phonation onset flow/pressure relationships and acoustics were measured.
  
  
  RESULTS
  Increasing depth of medialization led to improvements in fundamental frequency (F0) range and normalization of the slope of pressure/flow relationship toward baseline activation conditions. The effects of implant medial shape also depended on depth of medialization. Outcome measures were similar among the implants at smaller medialization depths. With large medialization depths and vagal paralysis conditions, the divergent implant maintained pressure/flow relationship closer to baseline. The vagal paralysis conditions also demonstrated decreased fundamental frequency range and worse flow/pressure relationship compared to RLN paralysis.
  
  
  CONCLUSIONS
  The depth and medial shape of a medialization laryngoplasty (ML) implant significantly affect both the F0 range and aerodynamic power required for phonation. These effects become more notable with increasing depth of medialization. The study also illustrates that ML is less effective in vagal paralysis compared to RLN paralysis.
  
  
  METHODS
  N/A.
authors.affiliation: Laryngeal Physiology Laboratory, Department of Head and Neck Surgery, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, U.S.A.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Orestes
authors.forename: Juergen
authors.initials: J
authors.lastname: Neubauer
authors.forename: Elazar
authors.initials: E
authors.lastname: Sofer
authors.forename: Jonathon
authors.initials: J
authors.lastname: Salinas
authors.forename: Dinesh K
authors.initials: DK
authors.lastname: Chhetri
mesh_terms: D000818:Animals; D001193:Arytenoid Cartilage / Q000601:surgery; D004195:Disease Models, Animal; D004285:Dogs; D058753:Laryngoplasty / Q000379:methods*; D010699:Phonation / Q000502:physiology*; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D012009:Recurrent Laryngeal Nerve / Q000503:physiopathology / Q000601:surgery; D012826:Silicone Elastomers; D016896:Treatment Outcome; D014826:Vocal Cord Paralysis / Q000503:physiopathology / Q000601:surgery*; D014827:Vocal Cords / Q000503:physiopathology / Q000601:surgery*; D014833:Voice Quality
chemical_list: D012826:Silicone Elastomers
keywords: Vocal fold paralysis; canine; medialization thyroplasty