Summary

Since the first description of this syndrome in 1979 by Susac, less than 100 cases have been reported in the literature. Susac syndrome is also referred to as SICRET (Small Infarctions of Cochlear, Retinal and Encephalic Tissue) and RED-M (Retinopathy, encephalopathy, deafness associated microangiopathy). Most patients are women (with a female to male ratio of 5.5:1) between 18 and 40 years. The pathogenesis of Susac syndrome is based on small vessel vasculitis with microinfarction due to arteriolar occlusions. The etiology is unknown. The syndrome is characterized by the triad of: encephalopathy; neurosensory hearing loss usually bilateral; branch retinal artery occlusions. However, the clinical picture may be incomplete, making the diagnosis difficult. Consequently, the disease frequency is probably underestimated. Headache can be prodromal, often preceding onset of Susac symptoms by several months. In more than 80% of cases, encephalopathy manifests as cognitive dysfunction or psychiatric disorders; more rarely, symptoms may include ataxia, sensory motor deficit, cranial palsies (III, IV, VI, VII), sphincteral deficit, etc. Laboratory tests are usely normal: cerebrospinal fluid examination may reveal elevated protein content and predominant lymphocytic pleocytosis (without IgG oligoclonal band). Cerebral MRI scans with gadolinium enhancement show small T2-weighted multifocal hypersignals during attacks. Fluorescein angiogram and audiometry confirm the retinopathy and the hearing loss, respectively. Differential diagnosis of Susac syndrome include multiple sclerosis, systemic lupus erythematosus, Gougerot-Sjogrën syndrome, some systemic vasculitides and thrombophilic disorders... Clinical course is characterized by recurrent attacks, occurring over a period of approximately 15 months, with a few months interval between attacks. Resolution usually occurs spontaneously and no deaths have been reported. However, sensory and neurologic sequelae, varying in severity, are present in one third of cases. Due to the lack of controlled studies, treatment is not well codified, and may include steroids, immunossuppressant drugs (azathioprine, cyclophosphamide), immunoglobulins, anti platelet agents, or even sometimes anticoagulant therapy.