Tests for treponemal antibody in CSF.

We studied the potential usefulness of CSF treponemal tests in the diagnosis of neurosyphillis. The CSF was tested with the microhemagglutination test for Treponema pallidum (CSF-MHA-TP test) and with the CSF-FTA test by using undiluted CSF and CSF diluted in saline and in sorbent. In a prospective evaluation, of 177 nonsyphilitics, none had reactive CSF-MHA-TP tests and only one had a reactive CSF-FTA test. However, five of 15 syphilitics with no other evidence of neurosyphilis had reactive CSF-FTA tests. The CSF-FTA test reactivity appeared most likely when the titer of the serum FTA test was high. In a retrospective evaluation of syphilitics with reactive CSF-FTA tests, similar patterns of reactivity occurred in patients with and without other evidence of neurosyphilis. Without other supporting clinical or laboratory data, the diagnostic value of a reactive CSF-FTA test is unknown.