Ototoxic Effect of Quaternary Ammonium Compounds

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Abstract
Chlorhexidine, when introduced into the middle ear of guinea pigs, causes serious damage to the inner ear. The quaternary ammonium compounds benzethonium chloride and benzalkonium chloride, frequently used for skin disinfection, may also induce inner ear damage when introduced into the tympanic cavity of guinea pigs. The disinfectants, at a concentration of 0.1% and in a solution of distilled H2O, or 70% alcohol, were introduced into the animals'' middle ear for exposure times of 10, 30 or 60 min. The animals were sacrificed 2 or 9 wk after the exposure, and the organ of Corti and vestibular neuroepithelia were studied as surface preparations with phase contrast microscopy. Most of the ears exposed to the disinfectants had suffered damage, affecting both the vestibular and cochlear parts of the inner ear. The extent of the damage was related both to the duration of exposure and to the length of the animals'' survival after the exposure. The tympanic cavity and the perilymphatic spaces of vestibulum and cochlea were pathologically changed.