Possible Effects of Cochlear Hydrops and Related Phenomena

Abstract

There is some question in the literature concerning the effects of hydrops on otoacoustic emissions (OAEs), and the usefulness of OAE measurement in the differential diagnosis of Ménière's disease and related disorders remains unclear. It is reasonable to expect different effects in various cochlear pathologies, especially between those causing primarily lowfrequency (LF) versus high-frequency (HF) hearing losses, as typically associated with putative fluid mechanical lesions versus hair cell damage, respectively. We report observations on distortion product OAEs in patients with LF and combinations of LF and HF losses and discuss problems of relating DPOAE output to the LF "hydrops" audiogram. We then describe effects specifically of intralabyrinthine pressure on OAEs, a possible factor in hydrops. It is clear from results in the literature and in our own clinics and laboratories that OAEs are sensitive to intralabyrinthine static pressure. These measures may or may not accurately reflect the hydrops hearing loss. The results are thus complex, doubtlessly reflecting the complexity and dynamics of diseases such as Ménière's. On the other hand, the effect of intralabyrinthine pressure per se is predictable and can be demonstrated to be rather predictable in humans.Learning Outcomes: As a result of this activity, the reader will be able to (1) explore the range of effects of Ménière's disease or hydrops on otoacoustic emissions and (2) learn of the sensitivity of otoacoustic emissions to intralabyrinthine pressure changes.

Effects of glycerol intake and body tilt on otoacoustic emissions reflect labyrinthine pressure changes in Menière’s disease

“…In contrast, the rationale of the present investigation did not focus on OAEs as objective audiometric tools. Instead, the goal of this study was to exploit the specific sensitivity of OAEs to perilymphatic pressure as reported in (Büki et al, 1996;Avan et al, 2000Avan et al, , 2001. Despite the persistence of sensorineural hearing loss at the time of the test, CEOAEs were present and could exhibit large amplitudes and broadband spectra.…”

“…Despite the persistence of sensorineural hearing loss at the time of the test, CEOAEs were present and could exhibit large amplitudes and broadband spectra. Indeed in MD, likely because the cochlear outer hair cells at the origin of OAEs are not the primary target of whatever produces auditory threshold fluctuations, OAEs tend to put up with a rather larger hearing loss than most other cochlear impairments (e.g., Avan et al, 2001;Fetterman, 2001).…”

Effect of Deliberate Ingestion of Organophosphate Pesticide on Distortion Product Oto-Acoustic Emissions (DPOAE)

“…However, some patients (30% of population) with abnormal OAE, consistent with cochlear dysfunction, will have normal pure-tone audiogram [15,16]. There is a consensus in the literature that OAE reception is highly stable [17,18] and the primary targets include noise induced hearing loss [19], Meniere's disease [20,21], oto-toxicity [22][23][24][25] etc., OAE have been suggested as a tool for the early detection of auditory damage due to diabetes [26] and noise [27]. However, there is no strong evidence that solvents induce damage to OHCs in humans.…”

OAEs and Meniere Disease

“…Although Roter et al [35] found that DPOAEs are not as accurate as the transtympanic electrocochleography, other authors [27,29,30] support the role of DPOAEs as a reliable method allowing the detection of endolymphatic hydrops and the cochlear damage in MD [19,33].…”

“…Considering that the acoustic energy has to cross the middle ear structures twice, OAE response may be reduced or even suppressed due to imperfections of the middle ear transmission mechanism. In this context, inner ear disorders can inluence the OAE response characteristics [27]. The endolymphatic hydrops (conined primarily in the cochlear duct and in the saccule [15]), increase the impedance at the level of the stapes, atenuating any forward or backward acoustic energy transmissions [28].…”