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A 37-year-old man with a black spot in his vision
Digital Journal of Ophthalmology 2010
Volume 16, Number 1
February 9, 2010
DOI: 10.5693/djo.03.2009.12.001
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Ann-Marie Lobo, MD | Massachusetts Eye & Ear Infirmary and Harvard Medical School
George N. Papaliodis, MD | Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, and Harvard Medical School
Diagnosis and Discussion
Susac syndrome

Susac syndrome is an arteriolar microangiopathy that affects the brain, retina, and cochlea, causing symptoms of encephalopathy, retinal vascular occlusions, and sensorineural hearing loss. It was originally described in 1979 by Susac, who reported on two cases of young women with this triad of symptoms.(1) Susac syndrome typically presents in younger patients, with ages ranging from 16-58. There is also a 3 to 1 predominance in women. The pathophysiology of Susac syndrome is still not well understood; however, it is believed to be an immune-mediated endotheliopathy affecting microvasculature of the brain, retinal vessels, and cochlea.(2) Brain biopsy of lesions in patients with Susac syndrome demonstrates microinfarcts in the cerebral cortex and white matter.(1) Muscle biopsies have also demonstrated endothelial cell necrosis and occlusion of small arterioles.(3)

As with this patient, the diagnosis of Susac syndrome may be difficult. The triad of symptoms may not manifest themselves concurrently, and visual and hearing deficits may be difficult to detect in encephalopathic patients. The differential diagnosis for Susac syndrome is extensive and includes demyelinating diseases such as multiple sclerosis and acute demyelinating encephalomyelitis (ADEM), CNS vasculitis, thromboembolic stroke, Behçet’s disease, and systemic lupus erythematosus. Ophthalmologic exam, including dilated fundoscopic examination and fluorescein angiography, can be helpful in identifying areas of retinal vascular occlusions and active retinal vasculitis.(4) FA may also be useful in tracking response to therapy, as in the improvement or resolution of vasculitis as seen in this case.(5) Neuroimaging may also be useful in the diagnosis as patients with Susac syndrome classically have lesions in the corpus callosum. Lesions are usually T2 hyperintense, may or may not enhance with contrast, and can be scattered in both the white matter and gray matter.(2) In some patients these hyperintense lesions may disappear as symptoms improve and return with exacerbation of disease. These findings may aid in the distinction between Susac syndrome and demyelinating diseases such as multiple sclerosis. The cerebrospinal fluid in patients with Susac syndrome may have elevated protein levels and mild pleocytosis.

The clinical course of Susac syndrome may be self-limited, with reports of symptom resolution from 6 months to 5 years following initiation of disease. Without treatment, the sequelae of Susac syndrome such as cognitive deficits, vision loss, and hearing loss can be quite severe.

The treatment of Susac syndrome is immunosuppression with high dose intravenous steroids and immunosuppressants such as cyclophosphamide, intravenous immunoglobulin, and rituximab.(3,4) There have also been reports of successful treatment with use of hyperbaric oxygen therapy.(6) Plasmapheresis has also been reported to result in improvement in cerebral deficits in some patients.(7) Anticoagulation has been proposed as a treatment option, but there have been no laboratory testing or histopathology to support a procoagulant state.(7) Patients who have been treated with anticoagulants or antiplatelet agents have continued to develop new symptoms during treatment. Of all the different treatment modalities, systemic steroids have been associated with improvement in symptoms and signs of Susac syndrome. While symptoms of active inflammation, including encephalopathy and retinal vasculitis, improve with immunosuppression, areas of prior infarction may result in permanent deficits in cognition, vision, or hearing. Delay in diagnosis can lead to permanent sequelae of the microangiopathic disease process. In some patients, symptoms may recur upon attempted taper of steroids and longer duration of immunosuppression may be needed to prevent exacerbations of disease.