BACKGROUND AND OBJECTIVES: Vestibular toxicity can be usually monitored by a caloric test, but measuring eye movements including nystagmus is also helpful in the evaluation of vestibulotoxic process. To understand the vestibular signs during bilateral vestibulotoxic process, we observed three dimensional serial changes of eye movements and the results of caloric test in cats using a magnetic search coil system. MATERIALS AND METHODS: Three-dimensional (3-D) eye movement responses to ice water caloric stimulus and spontaneous, positional, positioning, and post head shaking nystagmus in five cats were serially evaluated at 3, 7, 10, 14, 21, 28 days, 2, 3, 4, 5, 6 months after inducing bilateral vesitibulotoxicity by subcutaneous injection of streptomycin. Histologic changes of vestibular system were also observed. RESULTS: Bilateral vestibulotixicity which showed no response to ice water caloric stimulus was induced within 2 weeks with streptomycin injection. Positional, positioning and post head shaking nystagmus were present during vestibulotoxic process. Caloric nystagmus did not reappear within 6 months and histologic finding in crista ampullaris of lateral semicircular canal showed marked degeneration of the hair cells and nerves. CONCLUSION: Observation of positional, positioning and post head shaking nystagmus as well as ice water caloric test will be helpful to monitor vestibulotoxic process.
Animals ; Caloric Tests ; Cats* ; Eye Movements ; Hair ; Head* ; Ice ; Injections, Subcutaneous ; Nystagmus, Physiologic ; Semicircular Canals ; Semicircular Ducts ; Streptomycin ; Water