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

To observe the early and late effects of the parenteral administration of aminoglycosides on the dark cells of ampullae in the inner ear.

Comparative study of the histopathologic characteristic of human temporal bones.

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.

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.

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.