Evoked otoacoustic emissions (EOAE) were recorded from 39 ears with Meniere's disease, and the relationship between hearing thresholds, especially at a low-frequency range, and the “main frequencies”, at which the maximum power of the emissions were shown on the frequency spectra, or their changes by osmotic diuretics was mainly investigated.
No obvious correlation was found between hearing thresholds at a low-or mid-frequency range and the EOAE main frequencies. In most of the ears in which EOAE main frequencies were changed by administration of osmotic diuretics, their hearing thresholds at a low-frequency range showed normal or nearly normal after administration of the diuretics. In some ears with normal or nearly normal hearing at a low-frequency range, the EOAE main frequencies changed after administration of the osmotic diuretics or before vertigo attack, even though the hearing thresholds did not change.
These results suggest that some changes which could not be detected by conventional pure tone audiometry but by EOAE measurements, might occur in the cochlea by osmotic diuretics or before vertigo attack in normal or nearly normal hearing ears with Meniere's disease. It is, therefore, considered that the EOAE measurements might be useful to evaluate such changes in early stage of Meniere's disease.
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