Susac syndrome

Created 18/02/2022, last revision 21/07/2023

rare microangiopathy affecting the arteries of the brain, retina, and cochlea (retino-cochleo-cerebral dysimmune vasculopathy)
- in partial forms of this syndrome, only 2 of the 3 components are clinically apparent. There are reports of subacute bilateral sensorineural hearing loss with bilateral retinal artery occlusion without obvious cerebral dysfunction
described by John Susac in 1979 (first reported in 1973) (Pfaffenbach, 1973)
- initially termed “small infarctions of cochlear, retinal, and encephalic tissues (SICRET)” syndrome or “retinopathy, encephalopathy, and deafness microangiopathy (RED-M)” syndrome
predominantly affects women (3:1) in the 2nd-4th decade (range 7-72 years), often associated with delivery
the exact cause is unknown; autoimmune microangiopathy or autoimmune coagulopathy (with APL positivity) are considered (Bucciarelli, 2014)
- different pathogenetic mechanisms may cause the same clinical syndrome

Clinical presentation

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leukoencephalopathy with a tendency to involve the central corpus callosum
microinfarcts in the internal capsule – “string of pearls“
specific lesions in the corpus callosum – “snowball lesions“
grey matter involvement and leptomeningeal enhancement may be present (in approx. 30%)
- such findings are useful in the DDx of MS and ADEM

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widefield fluorescein angiogram can show artery occlusion
- often peripheral branch retinal artery occlusions – BRAOs
- segmental vessel wall increased fluorescence/leakage, capillary dropout, peripheral nonperfusion, and peripheral capillary changes
look for signs of uveitis

CSF
- oligoclonal bands are commonly absent
- sporadic lymphocytic pleocytosis or elevated CSF protein may occur
CBC: occasional monocytosis or eosinophilia
mild elevation of serum antinuclear and/or antiphospholipid antibodies

Suspected	Incomplete	Complete
1 symptom	2 symptoms	complete clinical triad (approx 13%)
absence of significant vascular risk factors (atherosclerosis and/or coagulopathy)
+ one of the following risk factors: female between 20-40 years of age female within 1 year of pregnancy presence of characteristic corpus callosum or periventricular lesions on MR

demyelinating diseases
- multiple sclerosis (MS)
- NMO
- ADEM
multi-infarct disorders
- CADASIL
- Binswanger’s disease
- MELAS
other autoimmune diseases
- antiphospholipid syndrome
- Behçet’s disease
- Takayasu arteritis
- granulomatosis with polyangiitis (Wegener’s)
- systemic lupus erythematosus (SLE)
- sarcoidosis
- Sjögren’s syndrome
infections
- Creutzfeldt Jakob disease
- Lyme borreliosis
- viral encephalitis
- syphilis
- Progressive Multifocal Leukoencephalopathy (PML)
malignancy/paraneoplastic syndrome

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