The European Guidelines on the management of syphilis suggest that ANS should be suspected and thus the lumbar puncture (LP) should be performed in cases of (1) late syphilis (acquired >2 years previously), (2) CD4+ cells ≤ 350/mm3 and/or a serum Venereal Disease Research Laboratory/Rapid Plasma Reagin (VDRL/RPR) title > 1:32, (3) “serological failure” after syphilis therapy, and (4) the use of alternative treatment for syphilis. Here, CD4 is linked to syphilis.