title: Phonation threshold pressure predictions using viscoelastic properties up to 1,400 Hz of injectables intended for Reinke's space.
abstract: OBJECTIVE
  Viscoelastic properties of numerous vocal fold injectables have been reported but not at speaking frequencies. For materials intended for Reinke's space, ramifications of property values are of great concern because of their impact on ease of voice onset. Our objectives were: 1) to measure viscoelastic properties of a new nonresorbing carbomer and well-known vocal fold injectables at vocalization frequencies using established and new instrumentation, and 2) to predict phonation threshold pressures using a computer model with intended placement in Reinke's space.
  
  
  METHODS
  Rheology and phonation threshold pressure calculations.
  
  
  METHODS
  Injectables were evaluated with a traditional rotational rheometer and a new piezo-rotary vibrator. Using these data at vocalization frequencies, phonation threshold pressures (PTP) were calculated for each biomaterial, assuming a low dimensional model with supraglottic coupling and adjusted vocal fold length and thickness at each frequency. Results were normalized to a nominal PTP value.
  
  
  RESULTS
  Viscoelastic data were acquired at vocalization frequencies as high as 363 to 1,400 Hz for six new carbomer hydrogels, Hylan B, and Extracel intended for vocal fold Reinke's space injection and for Cymetra (lateral injection). Reliability was confirmed with good data overlap when measuring with either rheometer. PTP predictions ranged from 0.001 to 16 times the nominal PTP value of 0.283 kPa.
  
  
  CONCLUSIONS
  Accurate viscoelastic measurements of vocal fold injectables are now possible at physiologic frequencies. Hylan B, Extracel, and the new carbomer hydrogels should generate easy vocal onset and sustainable vocalization based on their rheologic properties if injected into Reinke's space. Applications may vary depending on desired longevity of implant. Laryngoscope, 2010.
authors.affiliation: Department of Communication Sciences and Disorders, The University of Iowa, 334B SHC, Iowa City, IA 52242, USA. sarah-klemuk@uiowa.edu
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Klemuk
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Lu
authors.forename: Henry T
authors.initials: HT
authors.lastname: Hoffman
authors.forename: Ingo R
authors.initials: IR
authors.lastname: Titze
mesh_terms: D000180:Acrylic Resins / Q000008:administration & dosage*; D000399:Air Pressure; D001672:Biocompatible Materials; D003094:Collagen / Q000008:administration & dosage*; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives*; D020100:Hydrogels / Q000008:administration & dosage*; D007267:Injections; D010699:Phonation / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012212:Rheology; D013018:Sound Spectrography; D055682:Viscoelastic Substances; D014826:Vocal Cord Paralysis / Q000503:physiopathology*; D014827:Vocal Cords / Q000187:drug effects*
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; C471832:Cymetra; D020100:Hydrogels; D055682:Viscoelastic Substances; C479038:carbomer; C445362:hylan-B gel; D006820:Hyaluronic Acid; D003094:Collagen