To discuss an interesting case and pitfalls in diagnosing Susac's syndrome. 

Susac’s syndrome is an uncommon endotheliopathy, characterized by encephalopathy, hearing loss, and branch retinal artery occlusions. Typical age of onset is 20-40 years of age, with female predominance similar to other autoimmune syndromes.  MRI has been a valuable diagnostic tool due to classic findings in the corpus callosum, however the disease can present with infarcts to cortical, subcortical, retinal and cochlear tissue.  

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A 67-year-old female with history of Diabetes Mellitus type 2 presented with encephalopathy, with multiple infarcts on brain MRI.  On further collateral history, she had worsening hearing and vision for one year, with audiology testing demonstrating low and high frequency sensorineural hearing loss.  Inflammatory markers obtained were elevated.  Lumbar puncture showed elevated protein and pleocytosis.   Due to concern for vasculitis, steroids were started, with improvement in mental status.  Brain biopsy was performed, however it did not show evidence of vasculitis.  Follow up MRI brain showed new “cannon ball” T2-FLAIR hyperintensities within the splenium of the corpus callosum.  Retinal angiography was negative for branch retinal artery occlusion or Gass plaques, though this was limited due to macular degeneration and diabetic retinopathy. Steroids were restarted, with mental status improvement, however due to poor glucose control, steroids were tapered.  Due to worsening cognition, she was readmitted for plasmapheresis/IVIG, however the family declined as the patient was a Jehovah’s witness.  Brain MRI showed new areas of infarct, most notably in the body of the corpus callosum.  She did again have improvement in her mental status with restarting steroids, however unfortunately the patient passed away one month later.   

While brain biopsy was negative, her clinical triad, radiographic evidence, and improvement on steroids supports a diagnosis of Susac’s syndrome. Providers should be aware of atypical presentations of stroke for CNS vasculitis.