Gentamicin ototoxicity: clinical features and the effect on the human vestibulo-ocular reflex.

CONCLUSIONS

Gentamicin ototoxicity presents with gait imbalance and oscillopsia, but only rarely with hearing loss and vertigo. Sinusoidal rotational stimuli with high accelerations such as the bedside head-thrust test or rotational step changes in velocity are useful to diagnose bilateral vestibulopathy.

OBJECTIVE

To describe the salient clinical features and vestibular testing results in gentamicin ototoxicity.

PATIENTS AND METHODS

A retrospective review of the quantitative vestibular function testing results for patients presenting to the UCLA Neurotology Clinic with gentamicin ototoxicity over the past 10 years (n=35).

RESULTS

All patients presented with imbalance and 33 out of 35 had oscillopsia. Three patients reported a noticeable change in hearing and five reported vertigo. Of the 35 patients, 15 were in renal failure at the time of gentamicin administration. Patients with pre-existing peripheral neuropathy compensated poorly. Sinusoidal rotational testing demonstrated profoundly decreased gain and increased phase lead over the entire frequency range, with a subset of patients having relatively preserved gain at the intermediate frequencies (0.8-1.6 Hz) and low acceleration (<30 degrees/s). There was little or no response to high acceleration step changes in velocity. The time constant measured both by sinusoidal and step responses was ultra-low. All patients tested had a positive head-thrust test bilaterally.