Incomplete Susac Syndrome With Recurrent Retinal Occlusions and Vertigo: A Case of Early Immunosuppressive Success

Susac syndrome (SS) is a rare autoimmune microangiopathy that targets the brain, retina, and inner ear. Its variable and often incomplete clinical presentation frequently leads to misdiagnosis, increasing the risk of morbidity. We report the case of a 53-year-old Caucasian woman with a history of pityriasis lichenoides et varioliformis acuta (PLEVA) and severe myopia. She experienced recurrent branch retinal artery occlusion (BRAO) and retinal vein occlusion, following an episode of intense vertigo. Notably, her initial vascular occlusion occurred prior to the onset of vertigo. A comprehensive diagnostic evaluation excluded other potential etiologies, including systemic lupus erythematosus (SLE), Takayasu arteritis, giant cell arteritis (GCA), and other forms of vasculitis. Her clinical course, characterized by repeated retinal vascular events and episodes of peripheral vertigo, supported a diagnosis of incomplete SS. Incomplete SS is a phenotype in which two organ systems, in this case the retina and inner ear, are affected and events may be asynchronous. Early initiation of immunosuppressive therapy, including corticosteroids and mycophenolate mofetil, led to significant improvement in her vision. This case highlights the critical importance of early recognition and treatment of incomplete SS to prevent irreversible organ damage.