CHANGES IN OTOACOUSTIC EMISSIONS AND AUDITORY BRAIN-STEM RESPONSE AFTER CISPLATINUM EXPOSURE IN GERBILS

Ototoxicity associated with cis-platinum administration commonly prese nts as hearing loss and tinnitus. The hearing loss is usually an irrev ersible, high-frequency sensorineural loss, Histologic studies in huma ns and animals suggest that the outer hair cells (OHCs) are most susce ptible to cis-platinum. Evoked otoacoustic emissions (EOAE), as a meas ure of outer hair cell function, are potentially useful in following o totoxic insults involving OHCs, Distortion-product otoacoustic emissio ns (DPOAE) test frequency-specific regions of the cochlea and therefor e may be particularly well suited for monitoring ototoxic injuries, We measured distortion product otoacoustic emissions, at f2 = 2, 4, 6, 8 , 10, and 12 kHz, in gerbils after a single large dose of cis-platinum . Animals treated with saline served as controls. The findings were co mpared to auditory brain stem evoked response (ABR) thresholds, using tone pips of the same frequencies, The DPOAE and ABR thresholds were m easured before treatment and again 2, 5, and 14 days after drug admini stration, The changes in DPOAE were compared with the changes in ABR, No treatment effect was noted in the 2-day group, Animals treated with cis-platinum demonstrated significant elevation of DPOAE and ABR thre sholds compared with control animals at 5 and 14 days, There was no si gnificant difference between the threshold changes in the 5-and 14-day groups.