• The definition of ototoxicity in most clinical studies of aminoglycoside antibiotics is an increase in pure-tone threshold from a baseline audiogram ≥ 15 dB at two or more frequencies, or ≥20 dB at one or more frequencies. In this study, test-retest auditory threshold differences of this magnitude were found in a group of 20 normal volunteers who were not taking any known ototoxic drugs. Depending on which of the two criteria for ototoxicity are used, these data represent a 20% or 33% incidence of ototoxicity. We believe that many of the audiometric changes reported to represent aminoglycoside antibiotic ototoxicity may actually represent the normal test-retest variability of pure-tone audiometry. If this is true, the reported incidence of hearing loss due to aminoglycoside antibiotics may be exaggerated.
(Arch Otolaryngol Head Neck Surg. 1990;116:406-410)