Don’t always expect the classical triad in Susac syndrome: a case report

Abstract

Case Presentation: Susac syndrome is a rare autoimmune disease characterized by the triad of encephalopathy, branch retinal artery occlusions, and sensorineural hearing loss, resulting from a microangiopathy affecting the central nervous system, retina, and cochlea. The objective of this report is to present a case of this clinical entity, emphasizing that the complete symptomatic triad may not be present in the early stages of the disease and that a high index of clinical suspicion is required to establish the diagnosis and initiate immunosuppressive treatment. A 44-year-old female patient with a history of systemic arterial hypertension developed painless central and peripheral progressive visual loss in 2024, initially affecting the right eye and subsequently progressing to bilateral involvement, with hypertensive retinopathy being the initial diagnosis.. In March 2025, she began experiencing recurrent episodes of sudden left lower limb paresis, associated with ipsilateral hypoesthesia and impaired coordination, with spontaneous resolution after approximately 15 minutes. Brain magnetic resonance imaging (MRI) revealed multiple hyperintense lesions on T2-weighted and FLAIR sequences, some demonstrating diffusion restriction and contrast enhancement, distributed within the brainstem, center of corpus callosum (particularly involving the genus - classical snowball lesions ), corona radiata, and the right superior and precentral frontal gyri, consistent with acute and subacute ischemic lesions. CSF and MRI angiography were unremarkable. There were no hearing symptoms, and the audiometry was normal. Fluorescein angiography showed contrast leakage in the retinal arteries walls bilaterally, suggesting capillaritis, without retinal branch occlusion. Follow-up MRI studies demonstrated progression and confluence of ischemic lesions without evidence of recent acute ischemia. Steroids and mycophenolate mofetil were started with the disease control. Discussion: The multifocal pattern of white matter involvement, with classical snowball lesions, in association with documented retinal vasculitis, is highly suggestive of Susac syndrome, even in the absence of auditory involvement at this stage. In individuals who fulfill all 3 criteria, a definite diagnosis can be stablished .In cases with only 2 organs involved, th diagnosis should be considered as probable. This 2016 criteria proposed by Kleffner may not be sensitive enough for the diagnosis of Susac syndrome, as observed by Adi Wilf-Yarkoni et al in 2024, and this leads to underdiagnosis and delays in treatment Final Comments: We report a case of probable Susac syndrome with characteristic radiological findings and Fluorescein angiography suggesting capillaritis. Early recognition of this pattern is crucial for diagnosis, even in the absence of the complete clinical triad, and for the timely initiation of immunosuppressive therapy, aiming to reduce disease progression and long-term neurological sequelae