The CSF from persons treated in the secondary or latent stage of syphilis and without signs of neurosyphilis may be reactive. A nonreactive result in the FTA-ABS CSF test suggests the absence of neurosyphilis.The VDRL test performed on cerebrospinal fluid (CSF) is the recommended testand can be used to diagnose neurosyphilis in patients with a prior history of syphilis infection.The presence of neurosyphilis in untreated patients can be detected by the presence of pleocytosis, elevated protein, and a positive VDRL.