Evaluation of neurosyphilis in human immunodeficiency virus-infected individuals

The diagnosis of neurosyphilis in patients infected with the human immunodeficiency virus (HIV) remains problematic. We examined the use of the Treponema pallidum hemagglutination (TPHA) index and quantitative tests of CSF by means of microhemagglutination-T. pallidum for diagnosis of neurosyphilis in 58 HIV-infected persons with latent syphilis who had not recently received therapy for syphilis. Five patients (9%) had reactive CSF VDRL tests and thus had proven neurosyphilis. For 13 patients (22%), CSF findings were normal and revealed no evidence of neurosyphilis. For 40 patients (69%), abnormal CSF findings were characteristic of neurosyphilis, but their CSF VDRL tests were nonreactive. Twenty-five of the 40 patients with possible neurosyphilis had pleocytosis and elevated CSF levels of protein and/or IgG. Five (12.5%) of these 40 patients had positive TPHA indices that indicated intrathecal antitreponemal antibody production, a finding that provided greater support for the diagnosis of active neurosyphilis. With use of the TPHA index, patients with CSF abnormalities can be better classified in regard to their need for therapy for neurosyphilis.