Neurosyphilis presenting as visually asymptomatic bilateral optic perineuritis

A 39-year-old Caucasian man presented with headaches and retro-orbital pain but normal vision. Bilateral optic nerve swelling was found on funduscopy though optic nerve function and computed perimetry were normal and there was no relative afferent pupillary defect. CT venogram and MRI were unremarkable. Cerebrospinal fluid (CSF) opening pressure was normal on lumbar puncture and Treponema pallidum antibodies and T. pallidum particle agglutination test were positive on CSF analysis. He tested negative for HIV. Symptoms rapidly resolved with 2 weeks of intravenous benzylpenicillin. At 1 month follow-up, the right optic nerve swelling had reduced while the left optic nerve swelling had increased; his vision remained unaffected and he was symptom free and continued to have no objective evidence of optic nerve dysfunction.