Effect of early and late syphilis on central nervous system: cerebrospinal fluid changes and neurological deficit

Neurological examination and investigation of the cerebrospinal fluid (CSF) was performed on 24 patients with early and 180 patients with late syphilis. In 21 (12%) patients with late syphilis positive CSF treponemal test results and neurological deficits suggestive of symptomatic neurosyphilis were found. Concomitantly all but three patients with neurosyphilis showed one or more of the following abnormal CSF variables: CSF concentration of albumin X 10(3)/serum concentration (albumin ratio) greater than or equal to 7.9; mononuclear cells greater than 5 microliters: ratio of CSF to serum IgG concentrations/ratio of CSF to serum albumin concentrations (IgG index) greater than or equal to 0.7 or of IgM/albumin (IgM index) greater than or equal to 0.1; or oligoclonal CSF immunoglobulins. In 20 (95%) patients with neurosyphilis evidence of the production of treponemal antibodies within the central nervous system (CNS) was shown. Ten (48%) patients with neurosyphilis had been treated previously for late syphilis. These observations emphasise the need to screen for neurosyphilis in patients with late syphilis. Intrathecal production of treponemal antibodies was detected in six (25%) patients with early and 44 (28%) with late syphilis who did not show any neurological deficit. Intrathecal production of treponemal antibodies indicating that the CNS was affected led us to suspect asymptomatic neurosyphilis in these patients. Seventeen (11%) patients with late syphilis but no neurosyphilis and only one (4%) with early syphilis showed additional abnormal CSF variables. Surprisingly, six out of 22 patients with treated early and 20 out of 68 patients with treated late syphilis showed evidence of treponema antibody production within the CNS. We do not know whether these findings indicate that the CNS was affected because of inadequate treatment or merely reflect persistent synthesis of treponemal antibodies associated with cured infection. In one (4%) patient with early and in 21 (13%) with late syphilis but no neurosyphilis abnormal CSF variables in the absence of positive CSF treponemal test results were observed, which excluded syphilitic inflammation of the CNS.