ObjectiveWe report a favourable outcome following early treatment with rituximab in a patient with probable Susac’s syndrome (SuS).BackgroundDelayed treatment of SuS leads to significant morbidity, however there is no consensus in its management.ResultsA 34-year-old man presented with severe headache, subacute confusion and blurred vision developing over 4 months. The MRI brain revealed multiple supratentorial and infratentorial FLAIR/T2 hyperintense lesions in white and gray matter, including characteristic corpus collosum ‘snow ball’ lesions. The fundus fluorescein angiography (FFA) showed typical branch retinal artery occlusion, consistent with his bilateral decrease in visual fields. CSF showed high protein (3000mg/L) and pleocytosis (18X106/L). Following diagnosis of probable SuS, he was treated with high-dose corticosteroids on day 3 of presentation, followed by IVIG, mycophenolate and rituximab. He had significant improvement within 1 week. By 3 months, he returned to his neuropsychological baseline in majority of cognitive domains from moderate-severe dysfunction, with concurrent MRI demonstrating resolving white matter lesions and FFA showing less evident vasculitis. The treatment response was maintained with tapering of steroids (25mg at 12 months). He was able to return to his previous occupation as a paramedic by 1 year.ConclusionSuS is a rare, immune-mediated microangiopathy in which early recognition with aggressive immunosuppression is required to achieve optimal outcome. No randomized controlled trial (RCT) exists for the management of this condition. In this report, early recognition through multidisciplinary input and aggressive immunotherapy with rituximab resulted in a favourable outcome. However, RCT evidence is needed to guide management.