Clinical Features, Multimodal Imaging, and Neurological Differential Diagnoses in Recurrent Susac Syndrome

BACKGROUND: Susac's syndrome (SuS) is a rare microangiopathy, often consisting of a classic, pathognomonic, clinical triad of sensorineural hearing impairment, encephalopathy, and retinal arterial occlusions. The variable presentation of SuS leads to underdiagnosis, despite the syndrome standing as an important differential in a variety of ophthalmic, neurological, and psychiatric presentations. Low case numbers and a fast progressive clinical course add to the difficulty of early recognition and treatment. METHODS: We report on a case of Susac's syndrome in a 40-year-old woman with the classic clinical triad. We report multimodal imaging findings in a patient with recurrent Susac syndrome and discuss these findings in the context of the existing literature. Particular emphasis is placed on neurological differential diagnosis, especially differentiation from multiple sclerosis and other causes of retinal vascular occlusion with nervous system involvement.We summarise the literature of other conditions that can present with retinal vascular occlusion, their associated central nervous system involvement, and imaging changes. RESULTS: Multimodal imaging demonstrated branch retinal artery occlusion (BRAO) with corresponding retinal ischaemic changes on optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA), together with characteristic corpus callosal lesions on magnetic resonance imaging (MRI). The combination of retinal vascular occlusion and central corpus callosal involvement is useful in distinguishing Susac syndrome from important neurological differentials such as multiple sclerosis. CONCLUSIONS: This case illustrates an example of how combined ophthalmic and neuroimaging findings may support recognition of recurrent Susac syndrome and facilitate distinction from other neurological disorders presenting with retinal vascular occlusion, particularly multiple sclerosis.