Cognitive change after treatment for neurosyphilis. Correlation with CSF laboratory measures

The decision to re-treat a patient with neurosyphilis is usually based on the clinical response, cerebrospinal fluid (CSF), cell count, and CSF protein concentration. The value of the CSF Venereal Disease Research Laboratory (VDRL) test on its own as a marker for treatment response in neurosyphilis has not been established. To assess the usefulness of CSF markers for continuing infection, 12 patients with neurosyphilis were reevaluated 1 year after treatment. Change in cognitive functioning, as assessed by the Mini-mental State Examination (MMSE), was correlated with the CSF cell count, protein content, IgG index, and VDRL test titer at follow-up. A significant negative correlation was obtained between 1 year improvement in MMSE score and CSF VDRL titers at both the 6- and the 12-month follow-up examinations, and with the 6-month CSF protein concentration. These findings suggest that the CSF VDRL titer may be an indicator of continued Treponema pallidum activity in patients without obvious clinical deterioration.