Ototoxic effect of iodine disinfectants

It had been suggested that disinfectants which could trickle into the middle ear through a perforated drum during the skin sterilization preceding otosurgery might cause inner ear damage resulting in deafness. In animal experiments it has been shown that chlorhexidine, benzethonium- and benzalkonium chloride, when introduced into the tympanic cavity of guinea pigs, will cause rather extensive damage to the neuroepithelial receptors of the inner ear. In the present study, iodine, frequently used for skin disinfection, has been investigated as regards ototoxicity by locally exposing the middle ear in guinea pigs. The duration of exposure was 10, 30, or 60 min. The animals were sacrificed 2 weeks later and the organs of Corti and neuroepithelial receptors of the vestibular part of the inner ear were studied as surface preparations in phase-contrast microscopy. It was found that slight damage had occurred in the basal parts of the organ of Corti of those ears exposed to iodine or iodophor in 70% alcohol for 60 or 30 min and damage to the vestibular receptors was observed in ears exposed to iodophor in 70% alcohol for 60 min. In ears exposed to iodine or iodophor in aqua dest., no damage to the inner ear sensory epithelia was revealed.