Cumulative ototoxicity of aminoglycosides in cystic fibrosis patients: an evaluation by high frequency audiometry

Aminoglycosides were first introduced in 1945 with the development of streptomycin. Almost immediately the first case reports of ototoxicity were described in patients receiving the drug for tuberculosis. The potential to produce both vestibular and auditory toxicity became widely known effects of the use of all of the subsequently developed aminoglycosides. Although this toxicity has been known for greater than forty years, understanding the factors that influence the incidence and extent of ototoxicity still require extensive study. It remains unclear what places an individual most at risk for developing this toxicity. Exactly which parameters to monitor are debated, and the utility of such monitoring questioned. Much attention has been placed on measuring aminoglycoside serum concentrations and establishing a therapeutic range to both ensure efficacy and prevent both ototoxicity and nephrotoxicity. The purpose of this investigation was to evaluate cumulative effects of aminoglycoside therapy on high-frequency hearing thresholds. Specifically, the study evaluated whether or not differences in hearing thresholds could be detected between patients known to have received chronic aminoglycoside therapy versus those who have had no known exposure to ototoxic stimuli. This study design was similar to other investigations into noise-induced hearing loss in that one time audiograms of the patients were compared to single audiograms from normal individuals.