title: Effects of body tilt on multifrequency admittance tympanometry.
abstract: BACKGROUND
  Hydrops and abnormalities of inner fluid pressure are involved in some otologic diseases such as Ménière's disease (MD). However, demonstrating abnormal perilymphatic or endolymphatic pressure is challenging. Multifrequency tympanometry studies in MD patients demonstrated an increase of the width of conductance tympanograms (outside an attack) compared with controls. To confirm that the increase in conductance width is caused by hyperpressure and not hypopressure in these patients tested outside an attack, we assessed the effect of changes in inner ear fluid pressure caused by body tilt on the results of multifrequency admittancemetry tympanograms.
  
  
  METHODS
  A multifrequency tympanometry including conductance (G) tympanogram at 2 kHz and resonance frequency measurements were performed in 20 volunteers (40 ears) free of otologic or neurologic disease. The measures were collected in three different positions: vertical, supine, and Trendelenburg positions.
  
  
  RESULTS
  Changes in inner ear fluid pressure caused by body tilt induced an increase in the width of G tympanograms. In the vertical position, the mean value was 141.7 ± 56.5 daPa; in the supine position, it increased to 158 ± 58.3 daPa; and increased even more in the Trendelenburg position (20 degrees), with a mean of 184 ± 69.6 daPa (p < 0.01). Resonance frequency also increased in the Trendelenburg position.We conclude that the increased width of G tympanograms in MD patients outside an attack may be caused by an increase in inner ear fluid pressure.
authors.affiliation: ENT and Skull Base Surgery Department, Bordeaux 2 University Hospital, Bordeaux, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Franco-Vidal
authors.forename: Damien
authors.initials: D
authors.lastname: Bonnard
authors.forename: Olivier
authors.initials: O
authors.lastname: Bellec
authors.forename: Hans
authors.initials: H
authors.lastname: Thomeer
authors.forename: Vincent
authors.initials: V
authors.lastname: Darrouzet
mesh_terms: D000158:Acoustic Impedance Tests / Q000379:methods*; D000328:Adult; D001826:Body Fluids; D007758:Ear, Inner / Q000502:physiology*; D005260:Female; D018475:Head-Down Tilt / Q000502:physiology*; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology; D008875:Middle Aged; D011312:Pressure; D016683:Supine Position / Q000502:physiology*; D055815:Young Adult