NEFL and syphilis: There was a moderate correlation between CSF sTREM2 (log10) values and CSF NFL (log10) (r = 0.406, p < 0.001; Figure 2A) in NS group, while no significant correlation was found between CSF sTREM2 (log10) and CSF NFL (log10) in the syphilis/non-NS group (r = 0.02, p = 0.95; Figure 2B).