Abstract WP116: Clinical And Diagnostic Features On Cerebrospinal Fluid And Vessel Wall MRI Can Differentiate Primary From Secondary CNS Vasculitis

Introduction: Differentiating primary CNS vasculitis (PCNSV) from secondary CNS vasculitis (SCNSV) can be challenging based on brain imaging and cerebrospinal fluid (CSF) profile alone. Little is known about the diagnostic nuances of differentiating these 2 entities with CSF and vessel wall magnetic resonance imaging (VWMRI) as overlapping features may exist. We aimed to look at clinical features, serum & CSF biomarkers, and VWMRI differences between PCNSV & SCNSV. Methods: Patients presenting to our tertiary care center with a diagnosis of PCNSV or SCNSV between January 2015 and January 2021 were extracted from electronic medical record data. We included patients older than 18 years of age with active disease who had CSF studies and VWMRI data available. Demographic, clinical and diagnostic characteristics were reviewed and descriptive statistics were reported for comparison. Results: A total of 42 patients (24 with PCNSV and 18 with SCNSV) met study inclusion criteria. The SCNSV group was older (median age 43 years vs 41.5 years), had a higher proportion of male gender (78% vs 54%) and black race (22% vs 4%) compared to PCNSV. Patients with PCNSV more commonly had headache (63% vs 50%) and seizures (21% vs 11%) but less commonly had encephalopathy (42% vs 50%), focal neurological deficits (79% vs 83%) and constitutional symptoms (17% vs 33%). Patients with PCNSV more likely had positive antinuclear antigen levels (25% vs 11%) and elevated sedimentation rate (33% vs 25%) but less likely had elevated C-reactive protein (25% vs 33%) in blood. Comparison of CSF studies showed that the PSCNV group had a lower median CSF white blood cell count (10 cells/mm3 vs 43.5 cells/mm3 , both lymphocytic), lower median CSF protein count (62 mg/dl vs 82 mg/dl) and lower IgG index (33% vs 56%) in comparison to the SCNSV group. On VWMRI, PCNSV group had less diffuse (40 vs 54%) involvement and more anterior multifocal lesions (40 vs 15%) compared to SCNSV group with more large or medium-vessel involvement (70 vs 54%). Conclusion: Clinical and diagnostic differences with regards to CSF and VWMRI exist between PCNSV and SCNSV that can aid in differentiating these two entities. This can prove useful especially in undiagnosed systemic vasculitides presenting with CNS vasculitis.