[Susac syndrome, a rare cause of encephalopathy]

Susac syndrome is a rare disorder caused by autoimmune-mediated occlusions of microvessels in the brain, retina and inner ear. These occlusions lead to a characteristic clinical triad of central nervous system dysfunction, visual disturbances and vestibule-cochlear deficits. The diagnosis is based on clinical manifestations and complementary studies, which demonstrate the involvement of three systems. There are different treatments that include various immunosuppressive drugs combinations such as corticosteroids, intravenous immunoglobulin, mycophenolate mofetil, among others. We present the case of a 26-year-old woman with left hearing loss, tinnitus and episodes of recurrent vertigo, four weeks after bilateral blurred vision, cerebellar ataxia and encephalopathy. Magnetic resonance imaging of the brain showed multiple rounded hyperintense lesions in t2 and fluid-attenuated inversion recovery (FLAIR), hypointense in t1, at the middle level of the corpus callosum, internal capsule, cerebellum and right middle cerebellar peduncle. The audiometry evidenced bilateral perceptual hearing loss, predominantly in the left ear. Angiography by optical coherence tomography showed obstruction in the deep layer retina arteries. The Susac syndrome was diagnosed and treatment started with methylprednisolone pulses therapy, intravenously 1000 mg/day for 5 days, followed by maintenance with mycophenolate, which completely reversed the encephalopathy, with persistence of mild ataxia and hearing loss. It is important to know the clinical triad characteristic and the complementary studies necessary to arrive at the diagnosis, since immunosuppressive treatment can often be delayed. Our case had an excellent response to corticosteroids.