Distortion Product Otoacoustic Emissions in Acute Sensorineural Hearing Loss.

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Time course of acute sensorineural hearing loss cases mainly on sudden deafness (SD) with horizontal type audiograms was evaluated by means of pure tone audiometry (PTA) and Distortion product otoacoustic emissions (DPOAEs) together with Evoked otoacoustic emissions (EOAEs).As the PTA levels recovered, DP power in each frequency also improved to almost the same level as that of the healthy side with good correlation in the full and remarkable recovery groups. 1kHz DP power exclusively had good correlation to 1kHz PTA level than in other frequencies through the time course.In 6 cases which could be evaluated every DP frequencies, correlation coefficient value at 1,2 and 4kHz was calculated as high as 0.856,0.731 and 0.613 respectively. The value tended to be high in lower frequency. The inner ear function could be evaluated in frequency domain in some extent. However, DP power fulctuated day to day resulting in difficulty of evaluating the inner ear function at that instance.On the other hand, total echo power (TEP) of EOAEs showed excellently high correlation coefficient value to mean PTA level (quadratic method) of 0.952.No case was observed in which DPOAE had improved prior to the PTA level. It is difficult to predict the prognosis only with the result of DPOAE at that instant.