Neurosyphilis in AIDS

Abstract

The presence of cerebrospinal fluid (CSF) abnormalities does not necessarily predict the development of neurosyphilis. The characteristic spinal cord syndrome associated with parenchymatous neurosyphilis is tabes dorsalis. A more rapid development of neurosyphilis in HIV-infected individuals than would otherwise be expected may result from the impairment of delayed hypersensitivity. Despite the associated immunosuppression, serum nontreponemal titers at the time of presentation of neurosyphilis in the HIV-infected individual are typically high, averaging 1:128. In general, those neurologic manifestations occurring early in syphilis, namely, asymptomatic neurosyphilis and syphilitic meningitis, are readily treatable and typically resolve without neurologic sequelae. Dependence on the CSF for determining the adequacy of treatment for neurosyphilis in HIV-infected individuals often yields inaccurate results, due to the frequency with which CSF abnormalities are detected with HIV infection alone. Neurosyphilis is broadly defined as the occurrence of neurological complications due to infection with Treponema pallidum. While the diagnosis of syphilis is relatively straightforward with serum tests for demonstration of treponeme or immune response to this pathogen, the diagnosis of neurosyphilis is more complicated. The goal of neurosyphilis treatment is to reach treponemicidal levels of penicillin in the CSF. The best determinant of treatment adequacy for neurosyphilis is the resolution of CSF abnormalities, although it often yields inaccurate results in HIV patients because of irregularities due to HIV infection alone. HIV-seropositive patients should be monitored for neurosyphilis relapse for at least 2 years following treatment.