Vestibular and auditory toxicity in patients treated with aminoglycoside therapy
Clinical monitoring for vestibular and auditory toxicity is required for all patients being treated with aminoglycoside therapy.
Aminoglycoside-induced vestibular and auditory toxicity are not reliably predicted by aminoglycoside plasma concentrations. Toxicity can occur early in the treatment course or weeks after therapy has stopped, and can persist after stopping aminoglycoside therapy. Sudden idiosyncratic deafness (which has a genetic basis) occurs rarely.
Inform patients of the potential for vestibular and auditory toxicity and ask them to report balance or hearing problems, even after therapy has stopped. Regularly ask patients about:
- gait ataxia and imbalance
- oscillopsia (the subjective sensation of bouncing vision) and blurred vision during head movement
- hearing loss.
Spontaneous vertigo is not a feature of vestibular toxicity.
To monitor for vestibular toxicity, measure visual acuity (using a Snellen or other visual acuity chart) at rest and during passive sinusoidal head rotation at 2 Hz. A drop of more than 2 lines of acuity suggests vestibular hypofunction1.
In patients treated with an aminoglycoside for more than 5 days, consider formal vestibular function testing and high-frequency audiometric testing, if available. In patients requiring a prolonged course of an aminoglycoside, record baseline audiometry when therapy is started and periodically if therapy extends beyond 14 days.
If vestibular or auditory toxicity is detected, stop the aminoglycoside and seek expert advice.