title: Why do some children have good hearing results following type III and IV tympanoplasty? Current theories of middle ear mechanics.
abstract: BACKGROUND
  Middle ear reconstruction in children following tympanomastoidectomy for cholesteatoma is commonly limited to a Wullstein type III or IV reconstruction owing to ossicular erosion. The hearing outcomes of this procedure have been unpredictable. Nevertheless, there are children who have remarkably good hearing results despite having extensive and aggressive cholesteatoma surgery and limited reconstruction.
  
  
  METHODS
  The current theories of middle ear mechanics following tympanoplasty and ossicular reconstruction are reviewed. In addition, a selective retrospective chart review of pediatric type III and IV tympanoplasty at The Hospital for Sick Children between 1998 and 2003 is presented.
  
  
  RESULTS
  Nine patients were reconstructed with a type III (n = 3) or IV (n = 6) tympanoplasty. The mean pre- and postoperative air-bone gaps were 43.6 and 24.9 dB. Speech reception threshold improved from 37.5 to 22.8 dB. The changes were statistically significant (p < .05).
  
  
  CONCLUSIONS
  This series of patients demonstrated a statistically significant hearing improvement at long-term follow-up. The improvements are consistent with optimal hearing outcomes predicted by current theories of middle ear mechanics.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, The Hospital for Sick Children, University of Toronto, Toronto, Ontario.
authors.forename: Vincent Y W
authors.initials: VY
authors.lastname: Lin
authors.forename: Paolo
authors.initials: P
authors.lastname: Campisi
authors.forename: Jacob
authors.initials: J
authors.lastname: Friedberg
mesh_terms: D001299:Audiometry; D002648:Child; D018424:Cholesteatoma, Middle Ear / Q000601:surgery*; D005260:Female; D006309:Hearing; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome; D014433:Tympanoplasty / Q000379:methods*