title: A study of the histological behavior of a rabbit vocal fold after a hyaluronic acid injection.
abstract: The vocal fold structure is composed of tissues with many cells surrounded by the extra-cellular matrix. One of the most important components of the extra-cellular matrix is Hyaluronic Acid (HA). The aim of the study was to evaluate the inflammatory response of rabbit vocal folds after a local injection of Restylane HA.
  
  
  METHODS
  Twelve adult male rabbits randomly received a 0.1 ml injection of Restylane HA in one vocal fold and 0.1 ml of saline in the other vocal fold. The animals were prospectively subdivided into two groups; animals in one group were sacrificed after one week of follow-up and animals in the other group were sacrificed after 3 months. Slides were Hematoxylin-Eosin (HE), Masson Trichromic and Toluidine Blue stained.
  
  
  RESULTS
  Hyaluronic Acid was found microscopically in all specimens in both groups. There was more connective tissue surrounding HA, always associated with a mild inflammatory response. The longer exposure time did not increase the intensity of inflammation. Tissue necrosis and foreign body inflammatory reaction were not observed in both groups.
  
  
  CONCLUSIONS
  The study suggests that HA is a good alternative as a filling material in vocal folds when treating glottal insufficiency.
authors.affiliation: Clínica Otorrinos, faculdade de Ciências Médicas, Santa Casa de São Paulo. pauloperazzo@uol.com.br
authors.forename: Paulo Sérgio Lins
authors.initials: PS
authors.lastname: Perazzo
authors.forename: André de Campos
authors.initials: Ade C
authors.lastname: Duprat
authors.forename: Carmem
authors.initials: C
authors.lastname: Lancelotti
authors.forename: Fernanda
authors.initials: F
authors.lastname: Donati
mesh_terms: D000818:Animals; D005355:Fibrosis / Q000473:pathology; D006820:Hyaluronic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D007267:Injections; D007827:Laryngitis / Q000473:pathology*; D008297:Male; D023421:Models, Animal; D009336:Necrosis / Q000473:pathology; D011817:Rabbits; D011897:Random Allocation; D012720:Severity of Illness Index; D014827:Vocal Cords / Q000187:drug effects* / Q000473:pathology / Q000601:surgery
chemical_list: D006820:Hyaluronic Acid; C445361:Restylane