Serum and cerebrospinal fluid profiles for syphilis in Thai patients with acute ischaemic stroke

Abstract

The diagnosis of neurosyphilis is complicated in elderly patients who have cerebrovascular risk factors and present with ischaemic stroke. We performed an analysis of serum and cerebrospinal fluid (CSF) profiles for neurosyphilis in acute stroke patients, particularly in those with atherosclerotic risk factors. In sera, the rapid plasma reagin (RPR) test and Treponema pallidum haemagglutination assay (TPHA) were used. In CSF, the RPR and fluorescent treponemal antibody-absorption tests were used together with CSF white blood cell (WBC) count and protein level. Baseline characteristics, including atherosclerotic risk factors, severity of stroke and computed tomography brain scan images were collected. Of the total 284 patients, 24 (8.4%) had TPHA-positive sera, from which 29.2% had a positive CSF for syphilis. Seven stroke patients (2.5%), with a mean age of 65.7 years, were diagnosed with symptomatic neurosyphilis, and 71% of them had atherosclerotic risk factors. Most symptomatic patients (85.7%) had CSF WBCs>20 cells/mm(3), with a mean of 98.6 ± 136.0 versus 3.2 ± 7.3 in non-neurosyphilitic patients (P = 0.0009). Less than 50% of the symptomatic patients had CSF protein levels >50 mg/dL, and the protein levels of neurosyphilitic and non-neurosyphilitic groups were not significantly different, with means of 52.0 ± 12.9 and 51.8 ± 15.9 mg/dL, respectively. There were no significant differences in age and stroke severity. Interpretation of CSF findings, particularly of CSF WBC counts and protein levels, must be appropriate to ascertain true symptomatic neurosyphilis cases and to reduce false-positive diagnoses, particularly in countries with a high prevalence of T. pallidum infection.