Radiologically isolated syndrome (RIS) describes people without previous or current MS symptoms who have characteristic lesions on brain MRI seen in people with MS (pwMS). There are no clear evidence-based guidelines as to how to manage pwRIS. Imaging and blood-based biomarkers carry promise as potential tools to guide treatment decisions in pwRIS. We have previously shown that the majority of pwRIS show a high proportion of white matter lesions (WMLs) demonstrating the central vein sign (CVS) and have at least one paramagnetic rim lesion, an imaging biomarker of chronic, active WMLs in MS. (PRL). Glial fibrillary acidic protein (GFAP) is a potential blood biomarker being evaluated in MS. However, GFAP has not been studied in pwRIS, particularly in relation to the CVS and PRLs.

32 pwRIS underwent 3T brain and cervical spinal cord MRI and had pGFAP levels measured on an HD-1 Simoa platform (Quanterix). Spearmans correlation coefficient was used to evaluate correlations.

pGFAP levels correlated positively with the number of black holes, CVS+WMLs, and PRLs (p<0.05 using Spearman's correlation coefficient).

This pilot study is the first to demonstrate that pGFAP levels correlate positively with the number of: black holes, CVS+WMLs, and PRLs in pwRIS. Given the established relationships between black holes, PRLs and MS disease progression, pwRIS with high pGFAP levels may be at increased risk of developing clinical MS and disability over time. Prospective validation is underway to confirm the prognostic value of GFAP in pwRIS.