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

Abstract

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

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

Results: 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).

Discussion: 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.

Figure 1. FA Examination of a Patient's Left Eye Showing Multiple Leakages (Arrow) and BRAOs (Triangle) During an Active Phase of the Disease (A) and Complete Resolution of the Leakages Several Months Later (B)

BRAOs = branch retinal artery occlusions.

Figure 2. Proportion of Examinations Detecting Disease Activity Over Time

Figure 3. Comparison of the Total Number of Leakages and BRAOs (Both Eyes) Between the 3-Month Window Surrounding a Clinical Relapse and Outside This Window

BRAOs = branch retinal artery occlusions.