[Diagnostic problems in neurosyphilis].

In two patients admitted to hospital-one with signs of cerebral infarction, the other with headaches, vertigo and paraesthesias-the TPHA test was "reactive", while the 19S(IgM)-FTA-ABS test was not. There was no cerebrospinal fluid (CSF) pleocytosis. Further CSF analyses and serological tests for syphilis (including CSF protein profile, demonstration of oligoclonal IgG, quantitative determination of Treponema-specific antibodies in serum and CSF) confirmed the diagnosis of neurosyphilis requiring treatment. In both patients the biologically false-negative 19S(IgM)-FTA-ABS test at first became transiently reactive after treatment. This unusual finding was probably due to antigen, liberated by treatment, again stimulating previously blocked IgM antibody synthesis. The listed additional tests should be performed in all patients with a reactive TPHA test and neurological or psychiatric signs and symptoms.