title: Abnormal fast fluctuations of electrocochleography and otoacoustic emissions in Menière's disease.
abstract: The responses of cochlear hair cells to sound stimuli depend on the resting position of their stereocilia bundles, which is sensitive to the chemical and mechanical environment. Cochlear hydrops, a hallmark of Menière's disease (MD), which is likely to come with disruption of this environment, results in hearing symptoms and electrophysiological signs, such as excessive changes in the cochlear summating potential (SP) and in the postural shifts of distortion-product otoacoustic emissions (DPOAEs). Here, SP from the basal part of the cochlea and DPOAEs from the apical part of the cochlea were recorded concomitantly in 73 patients with a definite MD, near an attack (n = 40) or between attacks with no clinical symptoms (n = 33), to compare their sensitivities to posture and evaluate their stability. The phase of the 2f1-f2 DPOAEs was monitored during body tilt, with stimuli f1 = 1 kHz and f2 = 1.2 kHz at 72 dB SPL. Extratympanic electrocochleography was performed in response to 95-dBnHL clicks. The normal limits of the DPOAE phase shift with body tilt, [-18°, +38°], and of the SP to action-potential (AP) ratio, <0.40, were exceeded in 75% and 60% of patients, respectively, near an attack. In these patients, but not in the asymptomatic ones, both tests reveal fluctuating cochlear responses from one data sample to the next. They emphasize how hydrops hinders normal hair-cell operation and may generate fast fluctuations in inner-ear functioning. If these fluctuations also occur on shorter time scales, it might explain the imperfect diagnostic sensitivity of SP and DPOAE tests, as averaging procedures would tend to level out transient fluctuations characteristic of hydrops.
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France.
authors.forename: Grégory
authors.initials: G
authors.lastname: Gerenton
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Giraudet
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France; ENT Department, University Hospital, 30 rue Montalembert, 63000 Clermont-Ferrand, France.
authors.forename: Idir
authors.initials: I
authors.lastname: Djennaoui
authors.affiliation: ENT Department, University Hospital, 30 rue Montalembert, 63000 Clermont-Ferrand, France.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Pavier
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France; ENT Department, University Hospital, 30 rue Montalembert, 63000 Clermont-Ferrand, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Gilain
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France; ENT Department, University Hospital, 30 rue Montalembert, 63000 Clermont-Ferrand, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Mom
authors.affiliation: Laboratory of Neurosensory Biophysics, UMR INSERM 1107, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000, Clermont-Ferrand, France; Biophysics, Centre Jean Perrin, 30 rue Montalembert, 63000 Clermont-Ferrand, France. Electronic address: paul.avan@udamail.fr.
authors.forename: Paul
authors.initials: P
authors.lastname: Avan
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D016022:Case-Control Studies; D003051:Cochlea / Q000503:physiopathology*; D018159:Endolymphatic Hydrops / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008575:Meniere Disease / Q000175:diagnosis / Q000503:physiopathology*; D008875:Middle Aged; D017084:Otoacoustic Emissions, Spontaneous; D011187:Posture; D018667:Tilt-Table Test; D013997:Time Factors; D055815:Young Adult
keywords: Electrocochleography; Endocochlear hydrops; Hair cell physiology; Hydrostatic pressure; Otoacoustic emissions