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Susac Syndrome
KEY FACTS
Terminology
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Microangiopathy of brain, retina, and cochlea
Imaging
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T2 hyperintense corpus callosum lesions in patient with clinical triad
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Encephalopathy, bilateral hearing loss, and branch retinal artery occlusions
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Multifocal T2 hyperintensities similar to MS
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More often round, midcallosal rather than callososeptal location
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May involve brainstem, basal ganglia, thalamus, subcortical white matter, centrum semiovale
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Lesions may show acute diffusion restriction
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Variable enhancement of lesions and leptomeninges
Top Differential Diagnoses
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Multiple sclerosis
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Acute disseminated encephalomyelitis (ADEM)
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Systemic lupus erythematosus
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Vasculitis
Pathology
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Microinfarctions in cerebral cortex that are generally not seen on imaging
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No demyelination seen on pathology
Clinical Issues
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20-40 year old (F > > M)
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Sudden visual loss, deafness; headache, variable encephalopathy
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Usually self-limited (2-4 years), but may lead to permanent deafness or blindness
Diagnostic Checklist
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Most patients do not exhibit entire triad (up to 97% at time of presentation)
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Complete triad seen after 2 weeks or after 2 years
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Consider Susac syndrome in patients with corpus callosum lesions and clinical triad
Axial FLAIR MR shows multiple hyperintensities
in corpus callosum of this 27-year-old woman with Susac syndrome who presented with headache and confusion. The classic clinical triad includes encephalopathy, bilateral hearing loss, and branch retinal artery occlusions.
in corpus callosum of this 27-year-old woman with Susac syndrome who presented with headache and confusion. The classic clinical triad includes encephalopathy, bilateral hearing loss, and branch retinal artery occlusions.
Postcontrast sagittal FLAIR in the same patient shows classic involvement
of corpus callosum body with hyperintense lesions. Note leptomeningeal enhancement
, which may be seen in up to 50% of patients.
of corpus callosum body with hyperintense lesions. Note leptomeningeal enhancement , which may be seen in up to 50% of patients.
Axial DWI trace shows multiple hyperintense lesions
, many of which had corresponding low ADC values representing true diffusion restriction. Acute lesions may mimic vasculitis.
, many of which had corresponding low ADC values representing true diffusion restriction. Acute lesions may mimic vasculitis.
Funduscopic examination shows multiple retinal artery branch occlusions and irregularities
, classic for Susac syndrome. Susac syndrome is often mistaken for multiple sclerosis on imaging studies. Its etiology is uncertain but most likely represents an autoimmune microangiopathy, not a demyelinating disorder.
, classic for Susac syndrome. Susac syndrome is often mistaken for multiple sclerosis on imaging studies. Its etiology is uncertain but most likely represents an autoimmune microangiopathy, not a demyelinating disorder.
TERMINOLOGY
Synonyms
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Retinocochleocerebral vasculopathy, formerly known as small infarctions of cochlear, retinal, and encephalic tissue (SICRET syndrome)
Definitions
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Microangiopathy of brain, retina, and cochlea
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