To review the clinical presentation, MRI features, epidemiology and treatment of optic neuritis secondary to syphilis infection

Until the last decade, ocular syphilis was nearly a historical diagnosis. However, the incidence of syphilis has been increasing in the US since 2000 and cases of ocular syphilis are similarly on the rise, making the diagnosis an important one to keep in mind when evaluating patients with optic neuritis. We present a case of optic neuritis due to syphilis in an HIV-negative heterosexual male.

The patient is a 33-year-old man who presented with three weeks of headache and vision changes. Vision from the left eye was consistently blurry, with episodic periods of visual darkening and loss lasting seconds at a time. He denied pain with eye movement. He had a retro-orbital throbbing headache of mild-to-moderate intensity without positional changes. He had a remote history of treated gonorrhea, with negative STD testing in 2011. He denied recent high-risk sexual behavior. His exam was significant for left papilledema and an enlarged blind spot, with no APD or red desaturation. Labs were significant for positive ANA, anti-syphilis antibody, and RPR. MRI was significant for optic nerve enhancement adjacent to the optic disc. He was diagnosed with and treated for ocular syphilis.

Ocular syphilis can occur in any disease stage and may involve multiple ocular structures including the uvea, optic nerve, and retinal vasculature. Ocular syphilis at any disease stage should be treated as neurosyphilis, even if CSF studies are unremarkable. Corticosteroids are sometimes used as adjuvant therapy when there is involvement of the optic nerve, posterior uvea, or sclera.

Optic neuritis secondary to syphilis infection should no longer be considered a “zebra” diagnosis. Syphilis screening should be included in all unexplained cases of optic neuritis, regardless of other medical history.