title: Acoustic phase shift: objective evidence for intralabyrinthine pressure disturbance in Menière's disease provided by otoacoustic emissions.
abstract: OBJECTIVE
  Still today, Menière's disease (MD) can be definitively diagnosed only on post-mortem findings of endolymphatic hydrops. Otoacoustic emission (OAE) phase has been shown to be highly sensitive to intracranial pressure. Preliminary analysis of OAEs in MD patients indicated high sensitivity to slight variations in intracranial pressure. The principal objective of the present study was to confirm this specific sensitivity of OAEs in MD.
  
  
  METHODS
  In a prospective study of 32 consecutive cases of acute MD seen in consultation or hospital, 20 patients (23 ears) underwent acoustic phase-shift test: i.e., seated vs. supine OAE phase centered around 1kHz, with results compared to controls.
  
  
  RESULTS
  The acoustic phase-shift test was performed in 62.5% of acute patients (58.9% of affected ears). In the control group, the 95% confidence interval for phase shift was between -30° and +45°. Phase shift was significantly elevated, beyond the normal interval, in 18 of the MD patients: range, -80° to +145°. Sensitivity was 90%. Overall, in patients in whom transient evoked OAEs (TEOAEs) were present, positive predictive value was 100% and negative predictive value 92.3%.
  
  
  CONCLUSIONS
  The acoustic phase-shift test proved useful and powerful in demonstrating pressure imbalance in acute Menière's disease.
authors.affiliation: Service d'ORL et de chirurgie cervicofaciale, hôpital Gabriel-Montpied, CHU de Clermont-Ferrand, 30 place Henri-Dunant, Clermont-Ferrand, France. tmom@chu-clermontferrand.fr
authors.forename: T
authors.initials: T
authors.lastname: Mom
authors.forename: A
authors.initials: A
authors.lastname: Montalban
authors.forename: A
authors.initials: A
authors.lastname: Bascoul
authors.forename: L
authors.initials: L
authors.lastname: Gilain
authors.forename: P
authors.initials: P
authors.lastname: Avan
mesh_terms: D000328:Adult; D000368:Aged; D007758:Ear, Inner / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000503:physiopathology*; D008875:Middle Aged; D017084:Otoacoustic Emissions, Spontaneous; D011312:Pressure; D011446:Prospective Studies