This article focuses on the epidemiology, clinical presentation, diagnosis, and management of neurosyphilis, with an emphasis on clinically relevant issues faced by the practicing neurologist.
The incidence of primary and secondary syphilis, the sexually transmissible stages of infection, has been on the rise for the past 2 decades. A concerning recent trend is the surge in cases of syphilis in women and of congenital syphilis. Neurosyphilis remains a relatively common complication that can occur at any stage of syphilis. Along with meningitis, meningovascular syphilis, which has been historically described as a late presentation of neurosyphilis, now frequently occurs as a manifestation of early infection. Late forms of neurosyphilis, including tabes dorsalis and general paresis, are less prevalent in the era of widespread penicillin use. As more laboratories adopt the reverse-sequence algorithm for syphilis testing, patients with serodiscordant results (ie, a reactive serum treponemal test with a nonreactive nontreponemal test) may present an increasingly encountered diagnostic challenge for neurologists. Although the CSF Venereal Disease Research Laboratory (VDRL) remains a mainstay of diagnostic testing for neurosyphilis, using a higher titer cutoff (greater than 1:320) for the Treponema pallidum particle agglutination assay (TPPA) from the CSF may improve the utility of the TPPA as a supporting criterion for the diagnosis of neurosyphilis. Penicillin G is the treatment of choice for neurosyphilis, although ceftriaxone may be a reasonable alternative therapy.
A high index of suspicion and awareness of the variable clinical presentations of neurosyphilis are essential to the approach to this treatable infection. Neurologists should be mindful of the limitations of serologic testing in the diagnosis of neurosyphilis and exercise clinical judgment to determine the likelihood of the diagnosis.