50. Neurosyphilis. Tabes dorsalis.

Neurosyphillis

Syphilis is a sexually transmitted disease, caused by Treponema pallidum. Its only host is humans.

• Has a systemic onset, can be both manifested and asymptomatic.
• Pathogenesis: The bacteria gains access to the body via miniscule abrasions on the skin or mucous membranes. Attachment to the host cells involves the action of a mucopolysaccaridase.
• Causes primary obliterative endarteritis of terminal arterioles. Leading to inflammatory and necrotic changes. There is no immunity to reinfection.

Neurosyphillis: is caused as a result of a syphilis infection, the CSF white blood cell count of 20 cells/μl or greater. Pathogenesis is similar to the rest of the body, parenchymal involvement is apparent. If left untreated then CSF abnormalities will develop into a clinically presented disease.

Clinical Features

• Syphilis is classified as primary, secondary, tertiary or quaternary. Tertiary (late) is presented by lesions that are caused by obliterative small vessel endarteritis, which in neurosyphillis involves the vasa vasorum of the CNS.
• Tertiary syphilis consists of 3 types

1. a. Neurosyphillis
2. b. Cardiovascular syphilis
3. c. Late benign syphilis

Of Neurosyphillis:

• The CSF is usually colourless except in cases with a spinal subarachnoid block where xantochromia may occur.
• CSF pleocytosis is the best measure of disease activity, the number of white cells will correspond to the clinical syndrome.
• The gross appearance of the CSF in syphilitic meningitis is usually normal, but fluid may be sometimes cloudy due to an increase in WBC count.
• The protein is usually increased
• The CSF content of gamma globulins is increased, and oligoclonal bands may be present.
• Infection with T. Pallidum results in the formation of 2 antibodies: non-specific IgG and IgM antibodies against lipid antigens and components of treponeme.
• These antibodies are tested by VDRL slide flocculation tests.
• The specific treponeme test is known as fluorescent treponemal antibody absorption test (FTA-Abs)
• Both tests show a positive response in plasma and CSF in neurosyphillis.

Signs and symptoms

Can be grouped into the following:

1. Neuropsychiatric are some of the most common manifestations; psychosis, delirium and dementia
2. Cerebrovascular: acute neurological deficit that is linked to a cerebrovascular accident
3. Ocular: uveitis, visual loss or optic nerve dysfunction
4. Myelopathy: acute, subacute or chronic dysfunction of the spinal cord (tabes dorsalis)
5. Seizures: usually partial seizures that are presented without secondary generalization or myoclonus
6. Brain stem/ cranial nerves

Specific symptoms can include:

• Personality changes including cognitive or behavioural impairment
• Ataxia
• Stroke