Ototoxic Effect of Quaternary Ammonium Compounds

In earlier investigations by the author it has been shown that chlorhexidine, when introduced into the middle ear of guinea pigs, caused serious damage to the inner ear. The present investigation was performed in order to study if the quaternary ammonium compounds benzethonium chloride and benzalkonium chloride, frequently used for skin disinfection, can also induce inner ear damage when introduced into the tympanic cavity of guinea pigs. The disinfectants in question, at a concentration of 0.1 % and in a solution of aqua dest. 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 weeks after the exposure and the organ of Corti and vestibular neuroepithelia were studied as surface preparations with phase contrast microscopy. It was found that 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. Furthermore it was found that the tympanic cavity and the perilymphatic spaces of vestibulum and cochlea were pathologically changed.Die Untersuchung ergab, dasz eine Mehrzahl der des-infektionsmittelexponierten Ohren Schaudigungen auf-wiesen, und zwar sowohl im cochlearen als auch im vestibularen Anteil des Innenohrs. Der Umfang der Schaudigungen war relatiert zur Expositionszeit und zur uuber-lebenszeit des Tieres nach dem Eingriff. Zusautzlich wurden pathologische Veraunderungen in der Paukenhouhle und in den perilymphatischen Rauumen des Vesti-bulums und der Cochlea festgestellt.