Platinum derivatives such as cisplatin damage cochlea in particular outer hair cells. On the other hand otoacoustic emissions (OAEs) are thought to be the products of outer hair cells movements. So OAE might be affected by platinum derivatives in some way. OAEs of the patients who were treated their malignant neoplasms with platinum derivatives were recorded and their changes were examined. Four of 16 patients showed the suppressive changes of OAEs in various way during their chemotherapy. The first patient showed reduction of the amplitude of evoked otoacoustic emission (EOAE) during treatment without the change of audiogram. And long after the chemotherapy, the ampulitude of OAE recovered to the first level. The second patient showed reduction of the ampulitude of the OAE evoked by 1.5kHz tone burst and simultaneously hearing impairment at high frequency (over 4kHz) was obsered. In the third patient the ampulitude of OAF evoked by 1.5kHz tone burst was reduced and spontaneous otoacoustic emission (SOAE) was disappeared during chemotherapy. In the last patient threshold of OAE evoked by 4kHz tone burst was raised and hearing impairment at high frequency was observed, but OAE evoked by 1.5kHz tone burst was not affected.
The results suggested that the early damages of the cochlea by platinum derivatives could be evaluated with OAEs. Particulary in the first and second cases, though the reductive changes were shown in their OAE evoked by 1.5kHz tone burst, no hearing impairment was observed in 1 and 2 kHz. So these results might mean that with OAEs, we could evaluate the early and subtle damages of cochlea by platinum derivatives that did not affect audiogram. In this study only 4 cases showed the changes in OAEs, the other 12 cases showed no change.
We evoked OAE by 1.5 or 4kHz tone burst, but the cochlea damages by platinum derivatives are said to occur on higher frequency in the early stage. So to detect the early damages of cochlea, we must use higher frequency stimulation for EOAE. But because of the acoustic specificity of human middle ear it is difficult to record OAE evoked by higher frequency. So to detect the earlier damages of cochlea by platinum derivatives, we should combine the other examinations such as high frequency audiogram or ditortion product OAE (DPOAE) which can be recorded in higher frequency.
