Neurosyphillis

Syphilis is a Sexually Transmitted Infection (STI) caused by the bacteria Treponema Pallidum. It is a systemic infection with a multitude of signs and symptoms depending on the stage of the infection. As such, syphilis is also known as “the Great Imitator” because the clinical presentation may appear similar to many other diseases.

There are four stages of infection: 

1. Primary syphilis – painless ulcer (or chancre) at the site of infection
2. Secondary syphilis – manifestations that include, but are not limited to, skin rash, mucocutaneous lesions, and lymph node swelling
3. Latent syphilis – this stage can last for a number of years with few or no symptoms
4. Tertiary syphilis  – gummatous lesions (soft, non-cancerous growths), neurological problems, or cardiac symptoms

In this article, we will focus on neurosyphilis. You can learn more about syphilis as an overall topic in a previous article:

What is Neurosyphilis?

Neurosyphilis occurs when the infection reaches the central nervous system i.e. the brain or spinal cord. Neurosyphilis can occur at any stage of infection, but tends to occur in tertiary syphilis. Therefore, neurosyphilis can occur within a few months, but could also develop after 10 to 30 years, of a syphilis infection. 

There are four different forms of neurosyphilis:

1. Asymptomatic (most common form)
2. Meningovascular
3. General paresis (muscle weakness)
4. Tabes dorsalis (slow degeneration of the neural tracts of the spinal cord)

Asymptomatic neurosyphilis occurs before symptomatic neurosyphilis. Early neurosyphilis affects the blood vessels and meninges (membranous coverings of the brain and spinal cord) whereas late neurosyphilis affects the brain and spinal cord itself.

Signs & Symptoms

Signs and symptoms vary widely depending on the form of neurosyphilis, including:

• Stroke
• Changes in personality
• Dementia, mania, or paranoia 
• Ataxia (loss of coordination of muscle movements, eg. leading to gait abnormality)
• Ophthalmic symptoms (eg. blurred vision, reduced color perception)
• Urinary symptoms (eg. bladder incontinence)
• Headache
• Giddiness
• Hearing loss
• Seizures 
• Hyporeflexia 
• Sensory impairment 

Risk Factors

The risk factors include: 

• High risk sexual behaviour from unprotected sex and multiple sexual partners
• Men who have sex with men
• Recreational drug use

Diagnosis

Syphilis is diagnosed either via blood tests or direct visual inspection using dark field microscopy. In practice, blood tests are more commonly used as they are easier to perform.

To diagnose neurosyphilis specifically, cerebrospinal fluid (CSF), which is a fluid surrounding the brain and spinal cord, is obtained via lumbar puncture and the Venereal Disease Research Laboratory (VDRL) test is performed on the CSF. 

Other laboratory investigations that may be performed include: cerebral angiogram, computed tomography (CT) or magnetic resonance imaging (MRI) scan of the brain, brain stem or spinal cord.

Treatment

Syphilis is treated with intramuscular injection of the antibiotic benzathine benzylpenicillin. Early syphilis is treated with a single dose whereas late syphilis is treated with a once-weekly dose for 3 weeks. 

For neurosyphilis, however, the treatment course is different as penicillin penetrates the central nervous system poorly. Instead, the treatment requires intravenous penicillin every 4 hours for 10 to 14 days.

Generally, follow-up blood tests are performed at 3, 6, 12, 24, and 36 months to ensure the infection has fully resolved. Follow-up lumbar punctures for CSF analysis are performed every 6 months. 

Prevention

Neurosyphilis can be prevented with the following measures:

• Safe sex practice, namely correct and consistent condom usage
• Avoiding high risk sexual behaviour. Aside from abstaining from sexual contact, the surest way of avoiding STIs is to be in a mutually monogamous relationship with a partner who has been tested and is free of STIs
• Regular STI screening and if syphilis has been detected, to receive early and prompt treatment
• In the case of an individual diagnosed with a syphilis infection, prompt partner notification and treatment helps to reduce the risk of undetected syphilis