Gentamicin Vestibulotoxicity is Uncommon with Modern Dosing Regimens: a Prospective Study Using Video Head Impulse Testing (P6.043)

Objective: To determine the incidence of gentamicin vestibulotoxicity (GVT) with modern dosing regimens, and to test the feasibility of routine video head-impulse testing on all patients given gentamicin. Background: Gentamicin can cause vestibulotoxicity through apoptosis of hair cells in the semicircular canal. The incidence of vestibulotoxicity with gentamicin is unknown but it can be clinically disabling when it occurs. Several authors have suggested routine vestibular testing on all patients receiving gentamicin; however this has not been trialled in the published literature. Design/Methods: Horizontal vestibulo-ocular reflex (HVOR) gain measurements were recorded on adult patients receiving gentamicin at our institution using EyeSeeCam. Recordings were taken at time zero (before or within 4 hours of initial gentamicin dose) and repeated each day of gentamicin treatment and 1, 2 and 3–5 days following the final dose. Changes in individual HVOR gain and group HVOR gain with time were determined. Relationships between HVOR gain and total gentamicin dose, dynamic visual acuity (DVA) and subjective imbalance were also analysed. Results: Ninety-two patients were recruited and began testing. Forty-seven patients (51%) were excluded, mainly because patients did not complete the minimum testing protocol. Of the 45 patients included in the analysis, none developed serial impairment of their HVOR gain. There was no evidence for a generalised reduction in group HVOR gain with time. HVOR gain on the first day following final gentamicin dose was not correlated with total gentamicin dose, DVA or subjective imbalance. Conclusions: GVT is uncommon with modern dosing regimens. Using the rule of threes, the rate of GVT is likely to be less than 6.7%. We found routine testing of all patients receiving gentamicin difficult, as a high number of patients were excluded as they did not comply with the minimum testing protocol. This is likely to have been affected by acute patient illness. Disclosure: Dr. Smyth has received personal compensation from Boeringher Ingelheim (NZ) Ltd. Dr. Mossman has nothing to disclose. Dr. Weatherall has nothing to disclose. Dr. Jolliffe has nothing to disclose. Dr. Taylor has nothing to disclose. Dr. Joshi has nothing to disclose. Dr. Thorne has nothing to disclose. Dr. Watson has nothing to disclose. Dr. Leadbetter has nothing to disclose. Dr. Mossman has nothing to disclose. Dr. Moss has nothing to disclose. Dr. Schneider has received personal compensation for activities with Actelion as a speaker. Dr. Schneider has received compensation for serving on the board of EyeSeeTec GmbH. Dr. Schneider holds stock and/or stock options in EyeSeeTec GmbH. Dr. Todd has received personal compensation for activities with EyeSeeTec GmbH as an employee.