Vestibular and cochlear ototoxicity of topical antiseptics assessed by evoked potentials

Objectives/Hypothesis: To evaluate and compare the effect of chlorhexidine gluconate, povidone-iodine, and alcohol-three antiseptics used before ear s urgery-on the function of the vestibular and co-chlear parts of the sand ra t's inner ear. The assessment of damage is based on the recording of vestib ular evoked potentials (VsEPs) and auditory brainstem response (ABR). Study Design: Prospective controlled animal study. Methods: Fat sand rats were r andomly assigned to five different groups, each receiving topical applicati on of a different agent: saline (control), gentamicin (ototoxic control), c hlorhexidine, povidone-iodine, and alcohol. Right-side total labyrinthectom y was performed, and a polyethylene tube was inserted into the left (contra lateral) middle ear. After baseline recordings were taken of VsEPs and ABR, each animal received five consecutive daily applications of the specific a gent into the left middle ear. Three days after the fifth application, evok ed potential recordings (VsEPs and ABRs) were repeated and compared with ba seline measurements. Results: Administration of saline affected neither VsE Ps nor ABR in contrast, as expected, neither of these responses could be re corded after gentamicin application. After application of chlorhexidine all waves disappeared in all sand rats. Alcohol caused the waves to disappear in some of the animals only. Povidone-iodine did not affect VsEP recordings and had only a small effect on ABR. Conclusions: Chlorhexidine and alcohol had a clear toxic effect on the vestibular and cochlear function of the in ner ear of the sand rat, whereas povidone-iodine did not. Thus, taking into consideration that this is an animal study, it appears that povidone-iodin e might be preferable to the other agents tested in disinfecting ears with a perforated tympanic membrane.