Fluorescein Angiography as a Surrogate Marker of Disease Activity in Susac Syndrome

To evaluate the sensitivity of fluorescein angiography (FA) in detecting disease activity in Susac syndrome.

We conducted a blinded analysis of all FA, brain MRI, and audiogram examinations performed throughout the follow-up of patients with Susac syndrome.

A total of 79 FA examinations, 85 brain MRI scans, and 49 audiograms were analyzed from 9 patients followed for a mean (SD) period of 6 (4) years. Disease activity was detected in 41.5% of FA examinations, 10.5% of MRI scans, and 25% of audiograms (FA vs MRI, p < 0.0001; FA vs audiogram, p = 0.06; audiogram vs MRI, p < 0.05). Within 3 months of clinical relapses, activity was observed in 57%, 24%, and 27% of FA, MRI, and audiogram examinations, respectively (FA vs MRI, p < 0.05; FA vs audiogram, p = 0.09; audiogram vs MRI, p = 1). Quantitative analysis of FA showed a mean (SD) of 2.5 (2.5) leakages (both eyes) during relapses compared with 1.2 (1.4) during remission (p < 0.05).

FA, particularly arterial leakage, demonstrated the highest sensitivity in detecting disease activity and may be a valuable tool for treatment management in Susac syndrome. Future studies with larger samples should aim to identify the optimal threshold of FA changes associated with an increased risk of relapse.