Temporal Bone Findings in a Case of Susac's Syndrome

Objective: To describe the histopathologic findings in the temporal bones of a patient with Susac's syndrome (SS). Background: The key clinical features of SS consist of symptoms of encephalopathy, visual defects due to occlusion of branches of the retinal artery, and sensorineural hearing loss. The otopathology in SS has not been described. Materials and Methods: A 51-year-old woman was hospitalized with severe headache, rapidly progressive encephalopathy, and bilateral low-frequency sensorineural hearing loss. Magnetic resonance imaging showed lesions of the corpus callosum. Fluorescein angiography of the eyes showed focal areas of irregular retinal artery caliber and leakage from small vessels. SS was diagnosed. She died of a pulmonary embolus 1 month after onset of symptoms. Both temporal bones were prepared in celloidin and examined using light microscopy. Results: Findings were nearly identical in both temporal bones. The apical halves of both cochleae showed widespread atrophy of structures of the cochlear duct (inner and outer hair cells, tectorial membranes, striae vasculares, spiral ligaments, and spiral limbi). The apical parts of both cochleae also showed apparent occlusion of capillaries within the stria vascularis and related areas of the cochlear duct. Cochlear neurons were present in normal numbers. There was no endolymphatic hydrops. The vestibular sense organs were normal for age. Conclusion: This first reported otopathologic case of SS with hearing loss showed atrophy and degeneration involving the apical halves of the cochlear duct without inflammation or infection. The findings were consistent with capillary occlusion as being responsible for the atrophy.