Syndrome de Susac fébrile mimant une encéphalite infectieuse aiguë

Susac's syndrome is a rare disease of the brain, the retinal, and the cochlear microvessels. Its pathophysiology is still incompletely understood. This syndrome is characterized by a subacute encephalopathy, sometimes with a psychiatric presentation and migraine-like headaches, occlusions of branches of the central retinal artery, and a bilateral hearing loss. A brain imaging showing ischemic lesions of the corpus callosum is highly suggestive of the diagnosis. However, the triad is rarely complete at clinical onset, and the most frequent inaugural symptom is the encephalopathy, yielding a broad differential diagnosis to be made in the emergency context. We report the case of a 56-year-old patient, immunodepressed by long-standing treatment with corticosteroids and methotrexate, who presented acute encephalitis suggestive of an infectious cause. The brain MRI, showing multifocal microinfarcts with involvement of the corpus callosum, led to the diagnosis of Susac's syndrome. The audiometry and the retinal angiopathy confirmed the diagnosis. We make a brief review of the recent literature on the natural history and of the treatment recommendations for Susac's syndrome.