Cochlear damage from chlorhexidine in guinea pigs

The disinfectant chlorhexidine has been extensively used as preoperative skin sterilizing agent. In the early 1970s it was suspected from clinical experience that inner ear damage with deafness might result from chlorhexidine accidentally introduced into the middle ear during preoperative skin disinfection. In order to study if chlorhexidine by local application in the middle ear has any ototoxic effect resulting in morphological changes in the organ of Corti, the tympanic cavity of guinea pigs was exposed to two different concentrations of the substance. Two different solvents were used and the duration of exposure was varied. The animals were sacrificed 2, 3, 4 or 10 weeks after exposure. In surface preparations of the organ of Corti, damage was seen in almost all exposed ears, related in extent to the concentration of chlorhexidine, the duration of exposure, and the time lapse after exposure. Furthermore, it was found that inner ear damage often extended beyond the organ of Corti and pathological changes were also observed in the mucosal lining of the tympanic cavity.