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  • Updated 05.15.2024
  • Released 08.25.1998
  • Expires For CME 05.15.2027

Susac syndrome



Susac syndrome presents with a triad of retinal arterial occlusion, deafness, and encephalopathy, although often not all of the components are evident at the onset. 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.

Key points

• Susac syndrome is typically a triad of encephalopathy, retinopathy, and hearing loss, but may have an atypical presentation.

• Over 400 cases have been reported in the literature, mostly in women.

• Special diagnostic procedures are audiometry, retinal angiography, and MRI of the brain.

• Important treatments include corticosteroids and immunotherapy.

• The syndrome is self-limiting but may persist for years, with a fluctuating 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 (92). American neurologist and neuro-ophthalmologist John Susac (1940-2012) defined the syndrome in 1979 as a noninflammatory vasculopathy causing small infarcts in the cochlea, the retina, and the brain (116; 31; 98).

It has been called “RED-M syndrome” for “Retinopathy,” “Encephalopathy,” and “Deafness-associated Microangiopathy” (75). Another proposal was to call it “SICRET syndrome” for “Small Infarctions of Cochlear, Retinal, and Encephalic Tissue” (110). The triad of microangiopathy of the brain and retina with hearing loss was ultimately dubbed “Susac syndrome” (114; 82; 86), although it is still referred to as SICRET syndrome in the French literature (72), and other authors prefer the term “retinocochleocerebral vasculopathy” (89).

Further cases of this syndrome were reported in subsequent years (11; 19; 109).

In partial or variant forms of this syndrome, only one or two of the three components are clinically manifest. Examples of this are reports of subacute bilateral sensorineural hearing loss with bilateral retinal artery occlusion, but without obvious central nervous system signs (128; 28). MRI findings may be abnormal in these patients in the absence of symptoms specifically referable to the brain (130). Cerebral and retinal involvement may occur without hearing loss (43). A branch retinal artery occlusion subset of this syndrome has been recognized (99).