Background: Susac syndrome (SuS) is a rare immune-mediated occlusive microvascular endotheliopathy affecting the brain, retina, and inner ear. While the triad of encephalopathy, vision loss, and hearing loss is well described, the cerebrovascular spectrum of SuS remains poorly defined. We aimed to systematically characterize cerebrovascular and multisystem features of SuS and hypothesized that cerebrovascular involvement would be common. Methods: We analyzed 68 patients with SuS who met the European Susac Consortium criteria, from the largest single-center retrospective cohort of SuS reported to date. Clinical data, including neurological, ophthalmologic, and audiologic evaluations, were abstracted from structured chart review. Multimodal imaging was reviewed, including brain MRI with and without contrast, fluorescein angiography (FA), optical coherence tomography (OCT), and audiograms. Clinical and imaging features were summarized with descriptive statistics, reporting medians (interquartile range IQR) for continuous and frequencies (percentages) for categorical variables. Results: Patients were predominantly female (75.0%) with median age 34 years (IQR 27–40). At presentation, 71.2% had confusion, 76.1% cognitive impairment, 82.4% hearing loss, and 90.8% vision loss; the complete triad was present in 69.1%. MRI was available for 57 patients, showing corpus callosum lesions in 84.2%, with additional involvement of cerebellum (47.4%), brainstem (24.6%), and middle cerebellar peduncles (15.8%). Deep gray matter lesions occurred in 35.1%, and leptomeningeal enhancement, often in the cerebellar folia, in 19.3%. WMD burden was frequently moderate-to-severe. Acute small vessel infarcts were seen in 52.6%, predominantly deep subcortical (96.7%) versus cortical (50%). Ophthalmologic evaluation revealed branch retinal artery occlusions in 75.9% (59.1% bilateral), vascular leakage in 62.3%, and retinal atrophy in 41.2%. Audiograms confirmed sensorineural hearing loss in 71.4% (Table 1). Conclusions: In the largest cohort to date, cerebrovascular involvement, including small vessel infarction and deep brain lesions, was a prevalent and underrecognized feature of SuS. These findings broaden the imaging spectrum beyond corpus callosum lesions and highlight SuS as a systemic endotheliopathy with important cerebrovascular manifestations. Future studies should clarify how cerebrovascular lesion burden influences inflammatory activity, relapse risk, and treatment outcomes.
MacLeod et al. (Thu,) studied this question.