Correlation of retinal vascular features in Susac syndrome - a key biomarker for early diagnosis and treatment monitoring

Background Susac syndrome, a rare microangiopathy of retina, cochlea and the brain, often evades early diagnosis due to fluctuating, incomplete clinical manifestation and various differential diagnoses. We hypothesize that, based on its specific clinical appearance on the level of the retina, SuS could be found earlier even in ophthalmologically inactive or triad-wise incomplete cases. To enhance demarcating SuS from clinically resembling retinal diseases, we juxtapose our SuS cases with fourteen cases of relevant differential diagnoses and point out characteristic similarities and differences. Methods Eighteen patients, three with definite SuS, one with probable SuS and fourteen with ischemic and/or inflammatory retinal vasculopathies of different etiology, received a comprehensive ophthalmological examination including fluorescein angiography. The SuS cases received multimodal imaging including fundus photography, fundus autofluorescence imaging, fluorescein and indocyanine green angiography and optical coherence tomography angiography. Functional assessment included best corrected visual acuity and visual field measurements. Results Clinical and angiographic characteristics allowed for differentiation of other retinal ischemic and/or inflammatory vasculopathies from SuS. Our detailed catalogue of ophthalmological features adds two new signs of SuS to the literature (Roth spots, pigment spots). Conclusions Early diagnosis of SuS can be achieved by analyzing retinal vascular features in many cases, even in silent ones. We recommend OCT and OCTA with additional lateral scans in suspected cases. Differential diagnosis is enhanced by our juxtaposition of similar retinal conditions and characteristic / pathognomonic retinal features of SuS. Trial registration : Our retrospective study was registered at the MHH ethics committee registry, registration number: 11570_BO_K_2024 registration date: October 21, 2024