Susac syndrome presents with a triad of retinal arterial occlusion, deafness, and encephalopathy. Since its recognition in 1973, over 400 cases have been reported in the literature. In this article, the author describes the clinical features, pathology, and diagnosis of this syndrome as well as atypical presentations. The pathological findings include microinfarcts in the territories of end arterioles of the brain, retina, and inner ear. MRI plays an important role in demonstrating the CNS lesions. Management of Susac syndrome is also discussed.
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• Susac syndrome is typically a triad of encephalopathy, retinopathy, and hearing loss, but may have an atypical presentation.
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• Over 400 cases have been reported in the literature, mostly in women.
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• Special diagnostic procedures are audiography, retinal angiography, and MRI of the brain.
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• Important treatments include corticosteroids and immunotherapy.
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• The syndrome is self-limiting and may go on for years, with fluctuations in its course.
Historical note and terminology
Since 1973 there have been reports of patients (mostly young women) presenting with a combination of retinal arterial occlusion, deafness, and encephalopathy (88). This syndrome was delineated in 1979 as a noninflammatory vasculopathy causing small infarcts in the cochlea, the retina, and the brain (108). It has been called “retinopathy,” “encephalopathy,” and “deafness associated microangiopathy,” or “RED-M syndrome” (72). Another proposal was to call it “SICRET syndrome” after the first letters of “small infarctions of cochlear, retinal, and encephalic tissue” (104). It is still referred to as SICRET syndrome in the French literature (69). The triad of microangiopathy of the brain and retina with hearing loss was finally dubbed “Susac syndrome” (106). Further cases of this syndrome were reported in subsequent years (09; 15; 103). It has been reviewed under the name of Susac syndrome (80; 83). Other authors have preferred the term “retinocochleocerebral vasculopathy” (86). In partial forms of this syndrome, only 2 of 3 components of the syndrome are clinically manifest; the third is silent. Examples of this are reports of subacute bilateral sensorineural hearing loss with bilateral retinal artery occlusion, but without obvious central nervous system signs (117; 22). MRI findings may be abnormal in these patients in the absence of symptoms specifically referable to the brain (119). Cerebral and retinal involvement may occur without hearing loss (39). These are also included as variants of Susac syndrome. A branch retinal artery occlusion subset of this syndrome has been recognized (95).