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Neurosyphilis - a Potentially Serious Infection

Published on Sep 11, 2020 and last reviewed on Sep 14, 2020   -  4 min read


Neurosyphilis is the infection of the brain and spinal cord in patients with syphilis, a sexually transmitted bacterial infection. Read the article to know about its types, diagnosis, and treatment.

Neurosyphilis - a Potentially Serious Infection

What Is Neurosyphilis?

Neurosyphilis is a chronic, life-threatening infection of the central nervous system (CNS), involving the brain and spinal cord. It is caused by the spirochete bacterium Treponema pallidum.

Despite the absence of a definitive diagnostic test, several sets of criteria are used for diagnosis of neurosyphilis, including high CSF (cerebrospinal fluid), WBC (white blood cells) count, and/or a reactive CSF, VDRL (Venereal Disease Research Laboratory) with clinical symptoms. Early and adequate treatment is the key factor in the prevention of active neurosyphilis. The intravenous administration of aqueous crystalline Penicillin G 18 to 24 million units (MU) per day every 4 hours or continuously for 10 to 14 days is the first-line regimen in the treatment of neurosyphilis.

It is believed that, in most cases, the dissemination into the central nervous system occurs in the early stage of the infection. However, the neurological presentation of the infection could appear at any stage of syphilis.

Most commonly, neurosyphilis develops in untreated individuals who progress to the tertiary stage of syphilis, 10 to 30 years following the primary infection.

Despite the rare prevalence of early neurosyphilis, it has been detected that the rate of occurrence is significantly related to the treatment and is ten times higher in people receiving inappropriate therapy compared to those who are not treated.

Types of Neurosyphilis and Clinical Manifestation:

Once the bacteria infects the central nervous system, the body response could vary from asymptomatic to symptomatic, including a variety of manifestations. Neurosyphilis compromises five types with different clinical manifestations:

  1. Asymptomatic neurosyphilis.

  2. Meningeal neurosyphilis.

  3. Meningovascular neurosyphilis.

  4. General paresis.

  5. Tabes dorsalis.

Meningeal Neurosyphilis:

In the case of meningeal syphilis, symptoms could usually appear during the first year following the bacterial invasion, though the duration can extend from a couple of weeks to a couple of years. The clinical features of meningeal syphilis include signs of meningeal irritation, such as headache, nausea, vomiting, stiff neck, and of cranial neuropathies affecting cranial nerves VII, VIII, VI, and II, which could lead to visual and hearing impairment. Adequate treatment is required for active infection in order to prevent the progression to more serious types of neurosyphilis.

Meningovascular Syphilis:

Meningovascular syphilis is another form of neurosyphilis, characterized by the presence of endarteritis (inflammation of the inner lining of the artery) and perivascular (surrounding the blood vessel) inflammation. The inflammation of the tunica intima and the surrounding artery causes a narrowing within the lumen of vessels, which eventually could contribute to the formation of cerebrovascular thrombosis, vessel occlusion, ischemia, and infraction. Usually, clinical manifestation starts to develop about seven years after individuals get infected. However, it could appear as early as a few months or delayed to several years following the initial infection.

The symptoms of meningovascular syphilis comprise the signs of meningeal syphilis with the presence of stroke syndrome, which mostly affects the middle cerebral artery and the branches of the basilar artery in young adults. In addition, it could be associated with subacute encephalitis presentation, including headache, insomnia, vertigo, and psychological disorders as decreased memory, mood change, and personality disorders.

Parenchymatous Syphilis:

Parenchymatous syphilis is composed of general paresis (general paralysis) and tabes dorsalis (locomotor ataxia), which are relatively rare regarding other forms of neurosyphilis, due to developed medical prevention, screening, and treatment. Typically, it develops as a result of cortical parenchymal damage following chronic meningoencephalitis. It occurs within several years after infection, usually 3 to 30 years in general paresis and 5 to 50 years in tabes dorsalis with an average of 15 to 20 and 20 to 25 years, respectively.

The presentation of general paresis is subdivided into early and late symptoms including headaches, irritability, decreased memory, personality changes, and insomnia in early manifestations, and emotional lability, memory loss, confusion, disorientation, delusions, and seizures in late manifestations. It is found to be as well associated with psychiatric disorders like depression, hallucinations, mania, and psychosis.

General paresis is a severe form of neurosyphilis, and patients could die within an average of 5 years if they are left untreated. Regarding tabes dorsalis, the clinical features could range from ataxic gait, pains in the limbs, balance problem, paraesthesia to bladder dysfunction, and vision loss.

Diagnosis of Neurosyphilis:

There is no definitive diagnostic test for neurosyphilis. However, several sets of case definition criteria were reported by the CDC to assist the classification of neurosyphilis into three groups: possible, likely, or verified. The diagnosis of neurosyphilis is considered possible when a reactive nontreponemal test (as VDRL, RPR) with a reactive treponemal test (as EIA, CIA, TP-PA) and clinical manifestations of neurosyphilis are detected without the presence of other possible causes for these findings.

While it is defined likely when all the above criteria are associated with elevated cerebrospinal fluid (CSF) protein or leucocyte count without other possible causes. Verified neurosyphilis is confirmed by the presence of reactive nontreponemal and treponemal tests with characteristic clinical symptoms and reactive VDRL in CSF without significant bloody contamination of the CSF.

Management of Neurosyphilis

Regarding the available treatments provided to patients with neurosyphilis, aqueous crystalline Penicillin G is used as first-line regimens, given intravenously at 18 to 24 million units (MU) either every 4 hours or continuously for 10 to 14 days. An alternative therapy could be offered instead of the recommended treatment and includes 2.4 MU of Procaine Penicillin administered by intramuscular injection once daily plus 500 mg of Probenecid given four times a day orally for a total duration of 10 to 14 days.

However, for late syphilis, an additional dose of 2.4 MU of intramuscular Benzathine Penicillin is recommended once a week for three weeks following previous regimens to establish an adequate duration of therapy. A follow-up after treatment is required to ensure a complete resolution of the infection. For that reason, a CSF examination should be performed every six months until normal results are detected. If CSF results remain abnormal within the next two years, patients need to be re-treated for neurosyphilis.


The latest data shows an increase in the total number of reported syphilis cases, including all stages, by 13.3 % from 2017 to 2018. Regarding the continuous rise of the overall syphilis rate, further public health interventions are required to reduce the numbers, control the spread, and prevent the progression of disease, especially with the absence of gold standard lab test methods. However, early application of adequate treatment could provide sufficient protection against active neurosyphilis and associated complications as neurological disorders, disability, and even death.


Frequently Asked Questions


Can Neurosyphilis Be Treated?

Yes, it is possible to treat neurosyphilis with medications like antibiotic Penicillin. The treatment usually lasts for two weeks. The doctor will recommend regular blood tests and monitoring of the cerebrospinal fluid levels for better curing rates.


How Do You Get Neurosyphilis?

The bacterium Treponema pallidum causes neurosyphilis. After the exposure to Treponema pallidum, it takes around ten to twenty years for the occurrence of neurosyphilis. It is known to occur in women over the age of 20 to 24 and men around 35 to 39. In some cases, the exact cause of neurosyphilis is not known.


Is a Patient With Neurosyphilis Contagious?

Yes, the patient with neurosyphilis is contagious. It is most commonly noted during the primary stage of neurosyphilis. In this stage, a sore or chancre develops at another site of the entrance of bacteria. It is usually painless but can contribute to the spread.


Does Dementia Happen In Neurosyphilis?

Yes, dementia can happen in neurosyphilis. The common health problems seen in neurosyphilis are weakening of the muscles, emotional disturbances, and slurred speech. This can progress into the condition of dementia.


How Do You Test for Neurosyphilis?

The diagnosis for neurosyphilis is carried out using physical examination and blood tests. If the later stage of neurosyphilis is suspected, the doctor will suggest you for a procedure called a lumbar puncture. It determines the extent of infection in cerebrospinal fluid.


Can You Have Neurosyphilis and Test Negative?

Some patients are known to be positive for neurosyphilis even after testing negative in a treponemal test. After testing the nontreponemal test, if the result is still negative, you probably do not have neurosyphilis. In some cases, a nontreponemal test is performed even after the positive results of a treponemal test. A nontreponemal test serves as an additional confirmatory diagnostic test.


What Stage Is Neurosyphilis?

Neurosyphilis often occurs at any stage of infection. The most common neurological symptom in the early part of syphilis is meningitis. It is known to occur along with the secondary stages, and it is usually seen within 12 months of initial infection.


Can You Recover From Neurosyphilis?

Yes, it is possible to recover from neurosyphilis. The good news for the patient is that 100 percent recovery is possible. After treatment, the patient should focus on preventive measures to maintain their good health. Medication therapy is helpful for most of the patients.


Can Neurosyphilis Come Back?

The rate of recurrence of neurosyphilis is rare. It does not mean that recovering from neurosyphilis does not cause an individual to affect again. Medical reports suggest that even after a successful recovery, some patients are noted to have a recurrence. So it is necessary to follow the instructions of the doctor to prevent severe complications along with recurrence.


What Happens to the Brain When Someone Has Neurosyphilis?

Neurosyphilis is an infection that specifically occurs in the brain and the spinal cord. It is a serious condition that could cause life-threatening complications—most of the patients with neurosyphilis experience a stroke in the initial month of infection. The blood flow to some parts of the brain is lost. This might result in a blood clot that will obstruct the arteries of the brain. In complicated cases, the brain cells will die, and the brain suffers temporary or permanent damage.


Can Neurosyphilis Be Detected by a Blood Test?

Yes, neurosyphilis can be detected with the help of blood tests. The only problem with blood tests is that it might require repetition of the tests after a prescribed period of time. However, blood tests are efficient in detecting the middle stage of neurosyphilis.


How Long Can You Wait Before Treating Neurosyphilis?

It is not advisable to wait for neurosyphilis treatment because it is a serious condition that requires immediate medical attention. The time taken for the completion of treatment procedures will last for more than two weeks. Since treatment is a long procedure, it is good to start the treatment as soon as possible. You should coordinate with your doctor to discuss the various treatment options.


How Is Neurosyphilis Transmitted?

Syphilis is transmitted through sexual routes. If it is left untreated, it can lead to a condition called neurosyphilis. The common cause of transmission is syphilis sores. Direct contact with these sores results in the transmission of neurosyphilis.


What are the types of neurosyphilis?

There are notably five types of neurosyphilis. They are:
- Asymptomatic neurosyphilis.
- Meningeal neurosyphilis.
- Meningovascular neurosyphilis.
- General paresis.
- Tabes dorsalis.


What Are the Symptoms of Neurosyphilis?

The common symptoms of neurosyphilis are:
- Numbness in the feet, toes, or legs.
- Abnormal walk or difficulties in walking.
- Mental problems, such as irritability or depression.
- Problems with thinking, such as poor concentration or confusion.
- Seizures, headache, or stiff neck.

Last reviewed at:
14 Sep 2020  -  4 min read




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