Distribution of hair cells of Corti's organ after treatment with aminoglycoside antibiotics (author's transl)

Abstract

The histopothological study of both cochleas of the inner ear was performed in an autopsy case which had been treated with a total dose of 55 g of streptomycin sulfate against pulmonary tuberculosis.Each hair cell was identified on the cochlear reconstruction of a whole mount specimen in both ears. Both inner and outer hair cells were counted in number separately: Outer hair cells 10121 (right) and 8529 (left), while inner hair cells 3140 (right) and 3141 (left). Both inner and outer hair cells were missing near the base of the cochlea due to streptomycin ototoxicity and probably due to ageing degeneration as well. Other degeneration patterns due to streptomycin included a more pronounced fragility of outer hair cells as compared with inner hair cells particularly in the basal part of the cochlea, and the loss of outer hair cells of the first row which was more distinct in the basal turn of the cochlea.The loss of inner hair cells was scarcely detected in the apical part of the cochlea, while that of outer hair cells was more pronounced in the apical part than in the middle part of the cochlea.Remaining outer hair cells were 76% (right) and 64% (left) of the normal figures, while inner hair cells were 92% in both sides of the ears. The reduction of both inner and outer hair cells was supposed to be the cause of the threshold elevation of both ears in the audiogram. However, the loss of hair cells seems to be too mild to explain the hearing loss. The discre- pancy between the threshold elevation and the loss of hair cells could be produced by the presence of functionally impaired hair cells.