Hearing loss in patients with vestibulotoxic reactions to gentamicin therapy.

OBJECTIVES To determine whether patients with vestibulotoxic reactions to gentamicin have hearing thresholds worse than predicted by distributions of better-ear hearing thresholds in people of the same age and sex in the general population, and, if so, to measure the severity and audiometric pattern of that hearing loss. DESIGN Retrospective case series from previously published prospective and retrospective studies of vestibular function in patients receiving gentamicin. SETTING Tertiary neurotological practice. PATIENTS Convenience sample of 33 consecutive patients seen for objective evidence of vestibulotoxic reactions after systemic gentamicin therapy. Twenty-five of 33 patients underwent valid and complete audiometry. MAIN OUTCOME MEASURES Age- and sex-corrected better-ear pure tone thresholds, 0.5 to 6.0 kHz. The better-ear audiogram was defined in 2 ways: primarily, the audiogram of the ear with the better average threshold at 0.5, 1.0, and 2.0 kHz; secondarily, the composite audiogram taking the better threshold for each frequency. RESULTS Patients exhibiting vestibulotoxic reactions to gentamicin therapy had hearing thresholds that were similar to those seen in the general population at 0.5, 3.0, and 6.0 kHz. Median thresholds were 6 to 7 dB worse than expected at 1.0 and 2.0 kHz (95% confidence intervals, 2-13 dB and 3-12 dB, respectively). The largest median difference was 15 dB at 4.0 kHz (95% confidence interval, 3-23 dB), but this difference was not significant for the more conservative composite definition of the better ear. CONCLUSIONS Patients with vestibulotoxic reactions to gentamicin therapy have little additional hearing loss compared with the general population. Physicians should monitor both auditory and vestibular function when aminoglycosides, especially gentamicin, must be used.