title: Pars flaccida displacement pattern in otitis media with effusion in the gerbil.
abstract: OBJECTIVE
  Our hypothesis is that otitis media with effusion causes stiffness loss in the pars flaccida of the tympanic membrane. This loss of stiffness may be persistent and may trigger the development of retraction pockets and cholesteatoma.
  
  
  BACKGROUND
  Otitis media with effusion is a very common disease in childhood. It can cause minor to moderate hearing loss and delayed speech development. Otitis media with effusion is a risk factor for retraction pocket formation.
  
  
  METHODS
  Otitis media with effusion was induced unilaterally in 15 gerbils by obstructing the eustachian tube with glue. The contralateral ears served as normal controls. As a measure of mechanical stiffness, pars flaccida peak displacement versus pressure was used. The displacement measurements were made with moire interferometry. This is a noncontacting optical technique with which the displacement of an object can be measured in real time.
  
  
  RESULTS
  The mean peak displacement of the pars flaccida in the group with otitis media with effusion was increased threefold as compared with normal controls. This difference was statistically significant.
  
  
  CONCLUSIONS
  There was a loss of mechanical stiffness in the pars flaccida caused by otitis media with effusion. This loss of stiffness may be persistent and may predispose for retraction pocket formation and cholesteatoma development.
authors.affiliation: Department of Otorhinolaryngology, Karolinska Hospital and Karolinska Institute, Stockholm, Sweden. larsson_christina@hotmail.com
authors.forename: Christina
authors.initials: C
authors.lastname: Larsson
authors.forename: Joris J J
authors.initials: JJ
authors.lastname: Dirckx
authors.forename: Dan
authors.initials: D
authors.lastname: Bagger-Sjöbäck
authors.forename: Magnus
authors.initials: M
authors.lastname: von Unge
mesh_terms: D000818:Animals; D004548:Elasticity; D005260:Female; D005849:Gerbillinae; D008297:Male; D015903:Moire Topography; D010034:Otitis Media with Effusion / Q000473:pathology / Q000503:physiopathology*; D038781:Otoscopy; D011312:Pressure; D014432:Tympanic Membrane / Q000473:pathology / Q000503:physiopathology*