title: Significance of laboratory findings for the diagnosis of neurosyphilis.
abstract: Our objective is to assess the specificity and sensitivity, and thus elaborate the relevance, of different laboratory findings for the diagnosis of neurosyphilis. One hundred and fourteen HIV-negative pairs of serum and cerebrospinal fluid (CSF) samples were examined by the Venereal Disease Research Laboratory (VDRL) test, a fluorescent treponemal antibody-absorption (FTA-ABS) test, microhaemagglutination assay with Treponema pallidum antigen (MHA-TP) test (serum) and Treponema pallidum haemagglutination assay (TPHA) test (CSF); further, albumin, total protein, and total IgG were determined and, in the CSF, cell count was performed. The donors were 60 patients with active neurosyphilis and 54 healthy persons with a former history of syphilis and with persisting positive results in the T. pallidum haemagglutination tests (serum: MHA-TP, CSF: TPHA), who supplied specimens for control. Albumin quotient, IgG index, TPHA index, modified TPHA index, Intrathecally produced T. pallidum Antigen (ITpA) index, its 2 modifications and, in 12 samples, the adenovirus group antibody (AVGA)/TPHA index were ascertained. The specificity and sensitivity of the TPHA index were 100% and 98.3%, of the modified TPHA index 50.0% and 96.7%, of the ITpA index 42.6% and 90.0%, of the modified ITpA indices 51.8% and 68.3% (first modification) and 53.7% and 63.3% (second modification). The AVGA/TPHA index yielded a specificity of 91.7% (11/12). The CSF VDRL test was positive in 55/60 (91.7%) of samples from patients with neurosyphilis and in none of the controls (0/54). A CSF-TPHA titre greater than 1:320 was observed in 59/60 (98.3%) of the neurosyphilis specimens and in none of the controls (0/54). A TPHA index above an outcome of 70, a positive CSF-TPHA test at a titre greater than 1:320 and, with lower sensitivity, the criteria of the Centers for Disease Control (CDC) guidelines yield the most reliable results for laboratory support to a diagnosis of neurosyphilis. The modified TPHA index, the ITpA index, and its 2 modifications produce results of minor sensitivity and poor specificity. Observations on the AVGA/THPA index are too limited yet for judgement. The diagnostic significance of a CSF-TPHA titre above 320 needs further confirmation on a greater number of observations made by different laboratories.
authors.affiliation: Ludwig Boltzmann Institute for Dermato-Venereological Serodiagnosis, Vienna, Austria.
authors.forename: A F
authors.initials: AF
authors.lastname: Luger
authors.forename: B L
authors.initials: BL
authors.lastname: Schmidt
authors.forename: M
authors.initials: M
authors.lastname: Kaulich
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood / Q000134:cerebrospinal fluid; D000942:Antigens, Bacterial / Q000097:blood / Q000134:cerebrospinal fluid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009494:Neurosyphilis / Q000097:blood / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000276:immunology; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014210:Treponema pallidum / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D011933:Reagent Kits, Diagnostic