Background British guidelines detail indications for, and interpretation of, cerebrospinal fluid (CSF) examination in those diagnosed serologically with syphilis. We wished to evaluate our current clinical practise.
Methods We retrospectively studied all consecutive CSF syphilis tests performed in a large centre in London, UK, over five years. Indications for the examination, patient demographics, HIV metrics, serological tests for syphilis, and treatment regimens were examined.
Results A total of 291 CSF syphilis investigations were reviewed. 19% (n = 54) were requested to confirm or refute a diagnosis of neurosyphilis. Indications included serological diagnosis of syphilis plus symptoms: headache (28%), neurocognitive decline (9%), ophthalmological symptoms (18%), hearing loss (9%), other cranial nerve involvement (6%), psychosis (4%), and treatment failure (6%).
Of this group, 37% (n = 20) were treated for neurosyphilis. 2% of those having had CSF examination for other indications were also treated for neurosyphilis (n = 5). All bar one patient were seropositive for syphilis.
Of those treated for neurosyphilis (n = 25), all were HIV positive and 88% were male. Breakdown of CSF analysis revealed: CSF syphilis enzyme immunoassay (EIA) +/VDRL+ in 4%; EIA+/VDRL- in 56%; EIA-/VDRL- in 20%; and EIA equivocal/VDRL- in 20%.
All patients in this group were treated in line with British guidelines.
Of the 34 cases not treated for neurosyphilis, results were: EIA+/VDRL- in 35%; and EIA-/VDRL- in the remainder.
No patient had a positive CSF VDRL in the absence of a negative CSF EIA.
Conclusion All patients with a positive VDRL in the CSF were treated for neurosyphilis, but this was a rare finding; 54% of patients who were CSF EIA+/VDRL- were treated for neurosyphilis. A proportion were treated for neurosyphilis despite CSF analysis refuting the diagnosis (EIA-). Cell counts, CSF chemistry, and clinical criteria may influence these differences. Further diagnostics may improve the sensitivity and specificity of CSF examination for neurosyphilis.