Objective method for differentiating between drug-induced vestibulotoxicity and cochleotoxicity

Hypothesis: An objective direct method is proposed to differentiate between drug-induced functional vestibulotoxicity and cochleotoxicity. Background: Many substances are ototoxic. Although there are objective meth ods to directly evaluate functional cochlear toxicity (auditory nerve brain stem responses [ABR]), it is more difficult to assess direct functional oto toxicity to the various vestibular end organs. Methods: Short-latency vestibular evoked potentials (VsEP) from different v estibular end organs and ABR, were used to assess functional impairment of the vestibular and cochlear end organs caused by daily injections of the am inuglycoside amikacin (known to be preferentially cochleotoxic) in guinea p igs. Results: There was no significant change in the various VsEPs, whereas ABR thresholds were elevated, confirming the selective functional cochleotoxici ty previously reported, as evaluated by other (mainly nondirect) methods. Conclusion: This study demonstrates the feasibility in general of using sho rt-latency evoked potentials to evaluate functional cochleotoxicity and ves tibulotoxicity of ototoxic drugs and to differentiate between them.