Effect of parenteral aminoglycoside administration on dark cells in the crista ampullaris

Objective: To observe the early and late effects of the parenteral administration of aminoglycosides on the dark cells of ampullae in the inner ear. Study Design: Comparative study of the histopathologic characteristic of human temporal bones. Subjects and Methods: Sixty-three temporal bones from 44 subjects (age range, 16-81 years) were examined by light microscopy. Three groups of temporal bones were selected for this study: group 1, 30 "normal" temporal bones from 22 subjects (mean age, 59 years; age range, 25-81 years) with no history or histopathologic findings of otologic disease or ototoxic drug use; group 2, 14 temporal bones from patients who received aminoglycoside treatment within 2 weeks before death; and group 3, 19 temporal bones from patients who received aminoglycoside treatment between 2 weeks and 6 months before death. Results: The mean ± SD number of dark cells in group 1 was 15.0 ± 2.47; in group 2, it was 17.3 ± 1.93 in the subjects who received gentamicin sulfate and 15.0 ± 3.08 in those who received kanamycin sulfate and tobramycin; in group 3, it was 14.6 ± 1.67 in the subjects who received gentamicin and 15.2 ± 2.31 in those who received kanamycin and tobramycin. The overall difference between the 3 groups was not statistically significant (P = .07). The cytologic characteristics of dark cells were similar in all 3 groups. The number of dark cells showed a decline with increasing age in group 1. Conclusions: The result of this study suggests that the treatment period was probably too short to destroy the dark cells. Therefore, long-term aminoglycoside therapy may be necessary to get a more permanent result.