Susac syndrome: an organ-specific autoimmune endotheliopathy syndrome associated with anti-endothelial cell antibodies.

Susac syndrome (SS) is the triad of encephalopathy, branch retinal artery occlusions (BRAOs), and hearing loss. Migraines may herald and accompany encephalopathy. Little is known about pathogenesis. Based on light microscopic findings in brain biopsy material analogous to anti-endothelial cell antibody (AECA)-mediated microvascular injury, we postulated that SS microangiopathy was attributable to AECAs. We examined serum samples from 11 patients with SS for AECAs; 9 were positive by indirect immunofluorescence and Western blot studies. A highly distinctive band on Western blots corresponding to a 50-kDa protein was observed in 8 positive SS samples; the other positive case exhibited specific reactivity with a protein band at 40 kDa. Of the 2 negative cases, 1 had been inactive since 1988; the other was an abortive variant characterized solely by BRAOs. There was enhanced surface binding of SS serum using live endothelial cell substrates compared with samples from healthy subjects. Additional serum samples from apparently healthy patients, 2 with atypical migraines, and patients with other forms of autoinflammatory disease did not show the distinctive band of immunoreactivity. SS is a distinct autoimmune endotheliopathy syndrome associated with AECAs; the antibody target seems specific in many cases and may be a disease biomarker. The exact role of AECAs in disease propagation remains unanswered.

Retinal and optic nerve head pathology in Susac's syndrome.

PURPOSE: This article describes the first retinal histopathologic findings in a patient with Susac's syndrome (SS). DESIGN: Observational case report. PARTICIPANT: A 51-year-old white woman diagnosed with SS. METHODS: Eyes from a 51-year-old white woman diagnosed with SS were obtained at autopsy. One retina was dissected and processed for adenosine diphosphatase (ADPase) flat embedding. Selected areas were processed further for transmission electron microscopy. MAIN OUTCOME MEASURES: Histopathologic examination using ADPase flat-embedding technique. RESULTS: There were vaso-occlusive changes in the retinal periphery resulting in small areas of capillary dropout. Cross-sections demonstrated serous filled spaces between the retinal blood vessels and the internal limiting membrane. Lumens adjacent to these spaces appeared compressed and sometimes closed, but without thrombosis. Decreased ADPase activity in some peripheral blood vessels suggested endothelial cell dysfunction and vaso-occlusion. In the optic nerve head, numerous corpora amylacea were observed in the vicinity of capillaries with thickened walls and narrow lumens. Transmission electron microscopy demonstrated thickened and amorphous vascular basal lamina and open endothelial cell junctions in some retinal blood vessels. CONCLUSIONS: The serous deposits with compression of retinal vessel lumens observed histologically probably represent the so-called string of pearls described clinically in SS. Chronic extension of these serous deposits along the vessel wall possibly are the cause of retinal arterial wall plaques as described by Gass and other investigators. In the optic nerve head, corpora amylacea are probably a result of microinfarcts resulting from optic nerve head capillary angiopathy. Accumulation of amorphous material in the basal lamina, loss of viable endothelial cells, and capillary dropout suggest that SS may be an endotheliopathy.

Gass plaques and fluorescein leakage in Susac Syndrome.

INTRODUCTION: Susac Syndrome (SS) consists of the triad of encephalopathy, branch retinal artery occlusion, and hearing loss. It is an autoimmune endotheliopathy that primarily affects young women. Two funduscopic findings, Gass plaques (GP) and arteriolar wall hyperfluorescence (AWH), have recently been described and are not only useful in making the SS diagnosis but also point to the endothelium as the site of autoimmune injury. In this report we wish to raise awareness of GP and AWH with this disorder. METHODS: Four selected SS cases are presented with fundus photographs revealing GP. Fluorescein angiographic photographs are shown describing AWH. RESULTS: GP are shown in several cases. These GP are unique in that they are yellow, sometimes refractile, and located distant from retinal arteriolar bifurcations unlike Hollenhorst plaques which are orange and located at retinal arteriolar bifurcations. Fluorescein angiography displays AWH of the retinal arterioles of patients with SS distant from affected vessels which has not been demonstrated in other retinal vasculitides. CONCLUSION: Small punctuate yellow GP are almost unique to this disorder and their characteristic location and color should assist in confirming the diagnosis. Fluorescein angiography should be performed in all patients with an unexplained encephalopathy to look for the characteristic AWH pattern that occurs in this illness.

Susac's Syndrome--update.

Susac's Syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusion (BRAO), and hearing loss (HL). It is an autoimmune endotheliopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). The age range extends from 7 to 72 years, but young women (20-40) are most vulnerable. Headache routinely accompanies the encephalopathy and may be constant (best explained by leptomeningeal involvement), migrainous, or both. Multifocal neurological manifestations--particularly bilateral long-tract signs--commonly accompany the encephalopathy, which is laden with psychiatric features, confusion, memory loss and other cognitive changes. Left untreated, dementia can ensue. SS has an unexplained proclivity for attacking the central corpus callosum. In its encephalopathic form, pathognomonic callosal lesions permit an immediate diagnosis. We believe that the diagnosis of SS can be made when only the encephalopathy and pathognomonic MRI lesions are present; the BRAO and HL need not be present. We have also found the "string of pearls" MRI finding--the studding of the internal capsules with microinfarcts--to be most helpful--if not pathognomonic. This sign is always associated with the clusters of corpus callosum lesions, is especially striking on diffusion weighted imaging, and is associated with long-tract findings. We discuss the newly appreciated BRAO subset of SS and offer preliminary treatment suggestions for this subset. We also call attention to our development of an International Collaborative Study of SS and an educational website (http://www.ucalgary.ca/susac).

Retinal infarcts in a patient with an acute confusional syndrome.

A 46-year-old man presented with acute confusional syndrome, ataxia, dysarthria, and right hemiparesthesia. Brain MRI showed small bilateral infarcts and fluorescein angiography revealed multiple peripheral retinal infarcts bilaterally. No visual loss was present, and no other organs were involved. The diagnosis of Susac syndrome (microangiopathy of the brain, retina and cochlea) was made and immunosuppressive therapy begun.

Treatment of Susac's Syndrome.

Susac's syndrome (SS) consists of the triad of encephalopathy, branch retinal artery occlusions (BRAO), and hearing loss. It usually affects women aged 20 to 40, but men are also affected, and the age range extends from 9 to 72 years. It tends to be unrecognized, even in major academic centers. The complete triad may not be present at the onset, which makes diagnosis more difficult. However, since this disorder is treatable, early diagnosis is important. The encephalopathy is usually associated with headaches, multifocal neurologic manifestations, and psychiatric features (particularly paranoia). MRI shows a white matter disturbance that is frequently confused with multiple sclerosis and acute disseminated encephalomyelitis. During the encephalopathy, the corpus callosum is always affected and shows central involvement--small to large "snowballs" and linear defects, "spokes." As the acute changes (microinfarcts) resolve, central callosal "holes" develop, a pathognomonic finding. The deep gray matter (70%) and leptomeninges (33%) also may be involved. Dilated fundus examination will reveal branch retinal artery occlusions. Fluorescein angiography may disclose pathognomonic staining of the arterioles proximal to the occlusions and of nonoccluded arterioles. The cochlear hearing loss, sometimes associated with vertigo, is usually bilateral, and deafness becomes a major disabling problem. Brain biopsies, anatomic observations, and responses to immunosuppressive therapy suggest that SS represents an autoimmune endotheliopathy in the microvasculature of the brain, retina, and cochlea. Treatment requires immunosuppression. High-dose corticosteroid therapy is the mainstay, but additional therapies such as intravenous immunoglobulin, mycophenolate mofetil, and cyclophosphamide are often necessary. Rituximab is the newest therapy to consider. Treatment should be prompt, aggressive, and sustained to avoid the dreaded residuals of dementia, deafness, and blindness.

Aggressive immunosuppressive treatment of Susac's syndrome in an adolescent: using treatment of dermatomyositis as a model.

We describe aggressive immunosuppressive treatment of an adolescent with Susac's syndrome (SS), a disease of the microvasculature in the brain, retina, and inner ear. Because the immunopathogenesis of SS appears to have much in common with that of juvenile dermatomyositis (JDM), the patient was treated with an approach that has been effective for severe JDM. The patient's outcome provides evidence for the importance of prompt, aggressive, and sustained immunosuppressive treatment of encephalopathic SS.

Susac's syndrome: 1975-2005 microangiopathy/autoimmune endotheliopathy.

Susac's syndrome (SS) consists of the clinical triad of encephalopathy, branch retinal artery occlusions (BRAO) and hearing loss. It is due to a microangiopathy affecting the precapillary arterioles of the brain, retina, and inner ear (cochlea and semicircular canals). Women are more commonly affected than men (3:1); the age of onset ranges from 9 to 58 years; but young women between the ages of 20 and 40 are most vulnerable. The encephalopathy is almost always accompanied by headache which may be the presenting feature. Multifocal neurological signs and symptoms, psychiatric disturbances, cognitive changes, memory loss, and confusion may rapidly progress to dementia. The MRI shows a distinctive white matter disturbance that always affects the corpus callosum. The central callosal fibers are particularly vulnerable and central callosal holes develop as the active lesions resolve. Linear defects (spokes) and rather large round lesions (snowballs) sometime dominate the MRI findings, which include cortical, deep gray (70%) and leptomeningeal involvement (33%). Frequently, the lesions enhance and may be evident on diffusion weighted imaging (DWI). The BRAO are best evaluated with fluorescein angiography, which may show the pathognomonic multifocal fluorescence. Gass plaques are frequently present and reflect endothelial damage. Brain biopsy shows microinfarction to be the basic pathology, but more recent pathological studies have shown endothelial changes that are typical for an antiendothelial cell injury syndrome. Elevated levels of Factor VIII and von Willebrand Factor Antigen reflect the endothelial perturbation. Despite extensive evaluations, a procoagulant state has never been demonstrated. SS is an autoimmune endotheliopathy that requires treatment with immunosuppressants: steroids, cyclophosphamide, and intravenous immunoglobulin, usually in combination. Aspirin is a useful adjunct.

Treatment of Susac's syndrome.

Susac's syndrome (SS) is an immune-mediated endotheliopathy that affects the microvasculature of the brain, retina, and inner ear. SS responds well to immunosuppressive therapies when treatment is prompt, aggressive, and sustained. Striking similarities exist between SS and dermatomyositis (DM), regarding immunopathogenesis, natural history, and treatment needs. We apply lessons learned from study of DM to SS, and offer our current treatment protocol for SS. Since these treatment guidelines are based mainly on anecdotal evidence, they represent only preliminary recommendations.

Retinal arterial wall plaques in Susac syndrome.

PURPOSE: To demonstrate retinal arterial wall plaques (RAWPs) in patients with Susac syndrome, a disorder that consists of the triad of branch retinal artery occlusion, encephalopathy, and hearing loss. The clinician may misinterpret these RAWPs as emboli. DESIGN: Observational case series. METHODS: Four patients (one man and three women, aged 21-38 years) were examined and followed. RESULTS: Four patients with Susac syndrome had RAWPs in association with branch retinal artery occlusions. They were present in six of eight eyes. The plaques were yellow to yellow-white and located usually away from retinal bifurcations. Retinal arterial wall plaques occur at the midarteriolar segments, whereas Hollenhorst plaques occur at vascular bifurcations. Four of six eyes had resolution of the plaques. CONCLUSIONS: Retinal arterial wall plaques may occur with branch retinal artery occlusions in Susac syndrome. This finding should help the clinician who is struggling to make a diagnosis in a patient with an enigmatic encephalopathy and/or hearing loss. These plaques may resolve over time.