Susac syndrome (SS) is an autoimmune microangiopathy that affects the brain, retina, and inner ear, causing a wide range of clinical manifestations. The triad of encephalopathy, visual disturbances, and hearing loss constitute the classic disease presentation.We describe an original clinical case of a young male with a definitive diagnosis of SS, who presented with disordered behavior and amnesia, initially manifested as a dissociative or anxiety disorder but with a fulminant evolution toward severe encephalopathy associated with retinal infarcts and sensorineural hearing loss.After the diagnosis of SS, aggressive immunosuppressive treatment was started with significant neurological improvement and favorable evolution during the follow-up period. SS is a rare but potentially devastating disease that can cause great disability if not properly diagnosed and treated. The onset of SS with behavioral or psychiatric manifestation can be misleading, causing a diagnostic delay.