Neurosyphilis

What happens in neurosyphilis

Syphilis is a sexually transmitted infection. Within weeks of infection, the bacterium often reaches the spinal fluid. Most people's immune systems clear it from there, but in some it persists and inflames the meninges (the brain's coverings), blood vessels or the brain and spinal cord itself. Syphilis cases have risen sharply in the US over the past decade, and neurosyphilis and eye syphilis have risen with them.

People with HIV, especially with a low CD4 count, are at higher risk and may progress faster.

Types and symptoms

Early neurosyphilis (months to a few years)

• Asymptomatic neurosyphilis: abnormal spinal fluid with no symptoms.
• Syphilitic meningitis: headache, stiff neck, nausea, sensitivity to light and cranial nerve problems such as facial weakness or hearing loss. See meningitis.
• Meningovascular syphilis: inflamed arteries cause stroke, often in younger adults, sometimes after weeks of headache, dizziness or personality change.

Ocular syphilis and otosyphilis

Syphilis can affect the eyes (uveitis, retinitis, optic nerve) or inner ear at any stage, sometimes as the only sign. Symptoms include blurred vision, floaters, eye pain, sudden vision loss, sudden hearing loss, tinnitus and vertigo. CDC guidance treats these the same as neurosyphilis, and they can cause permanent blindness or deafness if treatment is delayed.

Late neurosyphilis (10 to 30 years)

• General paresis: progressive brain damage causing memory loss, poor judgment, personality change, mood disorders, delusions or psychosis, then dementia, seizures and weakness.
• Tabes dorsalis: damage to the back of the spinal cord. It causes sudden shooting ("lightning") pains in the legs, loss of position sense so walking becomes unsteady, especially in the dark, numbness, bladder problems and damaged joints (Charcot joints).
• Argyll Robertson pupils: small, irregular pupils that narrow when focusing close up but not in response to light, a classic sign of late neurosyphilis.

Diagnosis

Blood tests

Two types of test are combined:

• Treponemal tests (such as TP-PA, EIA or CIA) detect antibodies to the bacterium and usually stay positive for life.
• Nontreponemal tests (RPR or VDRL) measure activity of infection, are reported as a titer (for example 1:64) and fall after successful treatment.

Spinal tap (lumbar puncture)

A lumbar puncture is recommended for anyone with syphilis who has neurological symptoms. Spinal fluid tests include:

• CSF VDRL: a positive result confirms neurosyphilis, but a negative result does not rule it out.
• CSF white cell count and protein: raised levels support the diagnosis.
• CSF FTA-ABS: sensitive, so a negative result makes neurosyphilis unlikely.

People with eye or ear symptoms and positive blood tests need an eye exam or hearing tests. A spinal tap may not be required if there are no other neurological findings, because treatment is the same.

Other tests

MRI or CT of the brain for stroke, gumma (a rare syphilis lump) or atrophy, HIV testing for everyone with syphilis, and cognitive testing in suspected general paresis.

Treatment

• Aqueous crystalline penicillin G given intravenously for 10 to 14 days is the recommended treatment. An alternative is daily intramuscular procaine penicillin with oral probenecid, if adherence can be assured.
• Penicillin allergy: doctors usually confirm the allergy and, if it is real, perform desensitization so penicillin can be given safely. Ceftriaxone is a possible alternative in some cases.
• Jarisch-Herxheimer reaction: fever, chills, headache and muscle aches within 24 hours of the first dose are common and pass within a day.
• Ocular syphilis may also need steroid eye drops or other eye treatment from an ophthalmologist.

Follow-up

• Repeat RPR or VDRL blood tests to check that titers fall.
• If the first spinal fluid showed raised white cells, a repeat spinal tap may be advised, especially in people with HIV, to make sure it normalizes.
• Notify sexual partners so they can be tested and treated, and test for other STIs.

Outlook

Early neurosyphilis, including meningitis and eye disease, often responds well, and many people recover fully. Damage that has already occurred, such as dementia, hearing or vision loss, or spinal cord injury, may improve only partly. Treatment stops further progression, so early diagnosis matters.

Prevention

Use condoms, get regular STI testing if you have new or multiple partners, and treat syphilis promptly with the correct stage-based regimen. Doxycycline taken after sex (doxy-PEP) is now recommended by the CDC for some men who have sex with men and transgender women to lower bacterial STI risk. Pregnant people are tested for syphilis to prevent congenital infection.

Frequently asked questions

What are the first signs of neurosyphilis?

Early signs depend on the type. They include headache, stiff neck, blurred vision or eye redness, sudden hearing loss or ringing, and stroke symptoms in a young adult. Many people have no symptoms at all, and abnormal spinal fluid is found only on testing.

How is neurosyphilis diagnosed?

It is diagnosed by combining positive syphilis blood tests with neurological symptoms and spinal fluid tests. A positive CSF VDRL confirms it, while raised white cells or protein in the fluid support it. Eye and ear forms are diagnosed by an eye exam or hearing test in someone with positive blood tests.

Can neurosyphilis be cured?

The infection can be cured with intravenous penicillin. Symptoms from early disease, such as meningitis or eye inflammation, often resolve. Damage from long-standing infection, such as dementia, blindness or spinal cord problems, may be permanent, but treatment prevents it getting worse.

How long after syphilis infection does neurosyphilis occur?

It can occur within weeks to a few years, as meningitis, stroke or eye and ear disease, or 10 to 30 years later as general paresis or tabes dorsalis. That is why anyone with untreated or partly treated syphilis needs evaluation for neurological symptoms.

Is neurosyphilis contagious?

Neurosyphilis itself is not spread by casual contact. Syphilis spreads through direct contact with sores during sex, and during pregnancy to the baby. Someone with neurosyphilis may also have infectious early-stage lesions, so partners should be tested and treated.