Otoconial Degeneration After Transient Ischemia Induced by Four-Vessel Occlusion in Rats

BACKGROUND AND PURPOSE: Ischemia of the inner ear may damage the otoconia. However, no study has explored any changes in the configuration of otoconia after transient ischemia of the labyrinth. METHODS: Nineteen 7-week-old Sprague-Dawley rats were randomly assigned to either the sham (n=5) or the experimental group (n=14). The rats in the experimental group were subjected to global ischemia for 20 minutes using a four-vessel occlusion model, and were sacrificed seven days after the procedure. The rats in the sham group were sacrificed without any procedure. The otolithic organs (utricle and saccule) were dissected out for scanning electron microscope. RESULTS: The otolithic organs in the sham group showed their normal gross configuration with a dense clumping of otoconia with a normal hexagonal morphology and a smooth surface. The otolithic organs in the experimental group also maintained a grossly normal configuration, but each otoconia showed irregular surfaces with numerous cracks or furrows, especially in the periphery of the otoconial bed. CONCLUSIONS: The current study showed that otoconial degeneration may occur even after transient ischemia of the labyrinth. This finding supports an association between cerebral ischemia and benign paroxysmal positional vertigo.