[Effect of aminoglycoside on ascending auditory pathway evaluated by evoked potentials]

Permanent ototoxic injuries frequently occur after long term administration of aminoglycosides (AGs). An attempt was made to evaluate the effects of AGs on both peripheral and central auditory systems in rats by brainstem auditory evoked potentials (BAEPs). A total of 43 Wistar rats were divided into 4 groups, and 4 kinds of AGs (gentamicin, tobramycin, amikacin and streptomycin) were applied respectively to rats in each group with IM injection daily for 9 weeks. BAEPs were recorded pre- and post-injection weekly. Rats with gentamicin administration had no apparent changes in peak latencies until 7 weeks when prolongations occurred. Tobramycin administration in rats caused peak latencies to prolong progressively. Prolongations of peak latencies initially followed by no more evident changes were present in rats with amikacin or streptomycin. However, few consistent changes in interpeak latencies were shown in all rats. These results indicate that ototoxicity occurs at the peripheral auditory system, and the involvement of central auditory pathway was uncertain.