Susac syndrome

K K Jain MD (Dr. Jain is a consultant in neurology and has no relevant financial relationships to disclose.)
Originally released August 25, 1998; last updated August 11, 2016; expires August 11, 2019

This article includes discussion of Susac syndrome; microangiopathy of the brain, retina, and cochlea; RED-M; retinocochleocerebral vasculopathy; retinopathy, encephalopathy, deafness-associated microangiopathy; SICRET syndrome; and small infarctions of cochlear, retinal, and encephalic tissue. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Susac syndrome presents with a triad of retinal arterial occlusion, deafness, and encephalopathy. Since its recognition in 1973, approximately 320 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.

 

• Approximately 320 cases have been reported in the literature, mostly in women.

 

• Special diagnostic procedures are audiography, retinal angiography, and brain MRI.

 

• Important treatments include corticosteroids and immunotherapy.

 

• The syndrome is self-limiting and may go on for years, with fluctuations in its 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 (Pfaffenbach and Hollenhorst 1973). This syndrome was delineated in 1979 as a noninflammatory vasculopathy causing small infarcts in the cochlea, the retina, and the brain (Susac et al 1979). It has been called “retinopathy,” “encephalopathy,” and “deafness associated microangiopathy,” or “RED-M syndrome” (Mass et al 1988). Another proposal was to call it “SICRET syndrome” after the first letters of “small infarctions of cochlear, retinal, and encephalic tissue” (Schwitter et al 1992). It is still referred to as SICRET syndrome in the French literature (Mala et al 1998). The triad of microangiopathy of the brain and retina with hearing loss was finally dubbed “Susac syndrome” (Susac 1994). Further cases of this syndrome were reported in subsequent years (Barker et al 1999; Castellanos et al 1999; Saw et al 2000). It has been reviewed under the name of Susac syndrome (O'Halloran et al 1998; Papo et al 1998). Other authors have preferred the term “retinocochleocerebral vasculopathy” (Petty et al 1998). In partial forms of this syndrome, only 2 of 3 components of the syndrome are clinically manifest; the third is silent. Examples of this are reports of subacute bilateral sensorineural hearing loss with bilateral retinal artery occlusion, but without obvious central nervous system signs (Weidauer and Tenner 1973; Delaney and Torrisi 1976). MRI findings may be abnormal in these patients in the absence of symptoms specifically referable to the brain (Wildemann et al 1996). Cerebral and retinal involvement may occur without hearing loss (Gass et al 1986). These are also included as variants of Susac syndrome. A branch retinal artery occlusion subset of this syndrome has been recognized (Rennebohm et al 2010).

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