title: [Diagnosis of endolymphatic hydrops using low frequency modulated distortion product otoacoustic emissions].
abstract: BACKGROUND
  The low frequency modulation of distortion product otoacoustic emissions (DPOAEs) is an objective audiometric method that appears to be a useful tool for the diagnosis of endolymphatic hydrops (EH), e.g. in patients with Menière's disease, or in those who present only some of the symptoms of the disease.
  
  
  METHODS
  Low-frequency modulated DPOAEs were registered in 20 patients with unilateral Menière's disease (13 women and 7 men, aged 40-66 years) and were compared to a control group matched in age and gender. As a diagnostic parameter, the 'modulation index' MI=1/2 MS/DM was used (MS or modulation span, being the difference between the maximal and the minimal DPOAE-amplitude, and DM, being the mean of the suppressed stationary DPOAE-amplitude).
  
  
  RESULTS
  In the patients with unilateral Menière's disease, MI was lower than in the control group. This difference was highly significant. In 56% of the patients' contralateral ears MI was lower than the cut off-value and significantly lower than in the control group, but did not differ significantly from the patients' ipsilateral ears.
  
  
  CONCLUSIONS
  The registration of low-frequency modulated DPOAEs is comparable to the generally applied transtympanic electrocochleography in its diagnostic validity. The method is fast and non-invasive and could be applied to monitor the course of the disease.
authors.affiliation: Hals-Nasen-Ohren-Klinik der Charité, Universitätsmedizin Berlin, Campus Mitte, 10117 Berlin.
authors.forename: A
authors.initials: A
authors.lastname: Hirschfelder
authors.forename: E
authors.initials: E
authors.lastname: Gossow-Müller-Hohenstein
authors.forename: J
authors.initials: J
authors.lastname: Hensel
authors.forename: G
authors.initials: G
authors.lastname: Scholz
authors.forename: D
authors.initials: D
authors.lastname: Mrowinski
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001301:Audiometry, Pure-Tone; D001489:Basilar Membrane / Q000503:physiopathology; D018159:Endolymphatic Hydrops / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000175:diagnosis / Q000503:physiopathology; D008875:Middle Aged; D009925:Organ of Corti / Q000503:physiopathology; D017084:Otoacoustic Emissions, Spontaneous; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D013018:Sound Spectrography; D014012:Tinnitus / Q000175:diagnosis / Q000503:physiopathology