Imbalance and Oscillopsia Due to Gentamicin Vestibulotoxicity (Unilateral and Bilateral) in 127 Patients (S48.004)

Abstract

Objective: To determine if there is any relationship between gentamicin vestibulotoxicity and gentamicin dose or dosing profile, and if there are ways of detecting early vestibulotoxicity. Background Gentamicin ototoxicity is exclusively vestibular, not cochlear and is almost always missed by prescribers; patients are referred to neurologists, sometimes years later, with undiagnosed imbalance, and oscillopsia. Design/Methods: We reviewed 103 patients with bilateral, and 24 with unilateral gentamicin vestibulotoxicity, seen between 1988-2010, to determine if there is any relationship between vestibulotoxicity and gentamicin dose, and ways of detecting early vestibulotoxicity. Results: Patients9 were aged 18-84 years (mean= 65). Presentation was with imbalance (50), oscillopsia (4), or both (61) and indeterminate (12). Only 3 might have developed symptomatic hearing loss, none developed vertigo. All had positive horizontal and vertical clinical Head Impulse Tests to one or to both sides. Total dose of gentamicin was 2 to 318mg/kg (mean= 47); daily dose 1.5 to 5.6mg/kg (mean=3.5); Seven patients had only one dose, 34 patients had fewer than 5 doses. Delay to diagnosis: 4 days to 15 years. Gentamicin was given appropriately in only 50% of patients, according to the Australian Antibiotics Guidelines (a PDR equivalent). Six patients with bilateral vestibulotoxicity and 3 with unilateral vestibulotoxicity had video-oculographic measurement of the Head Impulse Test which in each case confirmed the vestibular loss. Conclusions: Gentamicin vestibulotoxicity produces imbalance and oscillopsia but not vertigo or hearing loss, and develops regardless of how much gentamicin is given and can develop after one dose. In any patient with imbalance or oscillopsia due to unilateral or bilateral vestibular loss presenting after a hospital admission it is important to examine the treatment charts for evidence of gentamicin therapy. In a patient having gentamicin the diagnosis of vestibulotoxicity can be made by video-oculography, perhaps even at a stage when drug withdrawal might allow recovery from vestibular damage. Disclosure: Dr. Ahmed has nothing to disclose. Dr. Hannigan has nothing to disclose. Dr. MacDougall has nothing to disclose. Dr. Halmagyi has nothing to disclose.