Assessment of vestibular ototoxicity of ear drops by recording of vestibular evoked potentials to acceleration impulses

Introduction: The cochlear ototoxicity of several ear drops is well documen ted in the literature, but very few studies exist on the vestibular ototoxi city of these topical drugs. Goal of Study: To develop an animal model fur the assessment of the vestibu lar ototoxicity of ear drops. Materials and Methods: Two animal groups, consisting of five fat sand rats (FSRs) each, underwent unilateral labyrinthectomy. Normal saline was topica lly applied into the middle ear cavity of rats in the first group for 7 day s (control group). Rats in the second group were treated in the same way by topical gentamicin solution. Cochlear function was assessed by the recordi ng of auditory evoked potential (ABPs) thresholds, and vestibular function was assessed by the recording of vestibular evoked potentials: (VsEPs) to a ngular accelerations. Results: In the control group, except for the amplitude of the first wave, there was no significant difference in the VsEPs recorded before and after topical application. In the gentamicin group. VsEPs could nor be recorded a fter 7 days, and ABPs were recorded in one case only, with a threshold of 1 00 dB sound pressure level(SPL). Conclusion: VsEPs seem to be a reliable measure for evaluating the vestibul ar ototoxicity of topical ear drops.