NEFL and primary central nervous system vasculitis: Serum NfL levels (Figure 1) were significantly higher in active PACNS patients (median: 45.77 pg/mL; range: 8.76–617.48 pg/mL) than in the remission group (median: 6.68 pg/mL; range: 4.36–22.50 pg/mL; p = 0.001), as well as the healthy controls (median: 6.05 pg/mL; range: 1.81–37.73 pg/mL; p < 0.001).