Abstract
Burow's solution is a 13% aluminum acetate solution that is widely used for the treatment of otitis externa and chronic otitis media. The ototoxicity of this solution was reported by our group using animal studies focused on compound action potentials. Histopathological changes of the cochlea were reported by Suzuki et al., who applied Burow's solution on the round window membrane for one hour or two hours and harvested the temporal bones seven days later. In the present study, Burow's solution was used to fill the middle ear cavity of guinea pigs, and the temporal bones were harvested at 30 minutes, 24 hours and four weeks later. The 20 micron thick specimens were stained with Hematoxylin and Eosin, and the chronologic changes of the cochlea were studied with an image-filing software program. The spiral ganglion cells in the lower turns were reduced in number, and there was prominent protein precipitate in the inner ear fluid in the lower turns, indicating that the Burow's solution penetrates the round window membrane and diffuse towards the upper turn. The round window membrane was found to be thinner at four weeks, suggesting damage by the acid. New bone formation in the middle ear cavity was speculated to be occurring due to inflammation of the middle ear mucosa.
