Neurosyphilis

Question 1

Classic presentation of tabes dorsalis

Answer 1

• Lancinating pain
• Sensory ataxia
• Hyporeflexia
• Impotence and/or bowel and bladder dysfunction

Question 2

Rapid plasma reagin

Answer 2

Quite sensitive for primary and secondary syphilis, but NOT for neurosyphilis

Negative RPR does NOT exclude neurosyphilis

Unfortunately, it also frequently has a false-positive result

Question 3

Venereal diseases tests vs treponemal tests for neurosyphilis

Answer 3

VDRL and RPR are both less sensitive for neurosyphilis than primary or secondary syphilis

However, treponemal tests are both sensitive and specific for all forms of syphilis, including neurosyphilis. If a treponemal test is negative, syphilis has been effectively ruled out.

Question 4

Typical CSF findings of neurosyphilis

Answer 4

• Elevated CSF protein (up to 200 mg/dL)
• Lymphocytic pleocytosis less than 400/μL
• CSF VDRL positivity most of the time
• Elevated CSF IgG synthesis

Question 5

If RPR and VDRL are negative but neurosyphilis is still clinically suspected. . .

Answer 5

. . . serum Treponema pallidum-specific antibodies should be performed (aka treponemal tests)

These include:

FTA-ABS, TPHA, MHA-TP

Question 6

Why don’t we do treponemal tests all the time for syphilis?

Answer 6

They are much more expensive

Question 7

PCR for syphilis

Answer 7

Unfortunately, this test sucks

Useless. If RPR/VDRL fail, you should just go to treponemal tests instead.

Question 8

Serologic tests for syphilis cannot distinguish between. . .

Answer 8

. . . syphilis, pinta, and yaws

Pinta and yaws are nonveneral treponemal endemic diseases

Question 9

Pain in neurosyphilis vs viral sensory ataxia-cranial neuropathy syndromes

Answer 9

In viral etiologies (HIV, Hep B, Hep C), pain is burning

In syphilis, pain is lancinating (stabbing)

Question 10

Argyll Robertson pupils

Answer 10

Small pupils that constrict when focusing, but fail to constrict when exposed to a bright light. Often bilaterally miotic and irregular at baseline.

In other words, they are reactive to accomodation, but not to light

Classically caused by neurosyphilis. Can also rarely occur in MS, Wernicke’s encephalopathy, diabetes mellitus, Lyme, sarcoid.

Question 11

H reflex

Answer 11

Electrical equivalent to a monosynaptic stretch reflex

Reflects pathology along the afferent and efferent fibers and/or the dorsal root ganglion

Question 12

Primary, secondary, and tertiary syphilis

Answer 12

Primary: Skin or mucocutaneous lesion at the site of infection

Secondary: Disseminated skin or mucocutaneous lesions reflecting syphilitic bacteremia

Tertiary: Neurosyphilis or Tree bark aorta. May occur years later.

Question 13

Classic exam findings of neurosyphilis

Answer 13

• Argyll Robertson pupils
• Hyporeflexia
• Symptoms localizing to the dorsal column
• Often some cranial nerve abnormalities

Question 14

Features of syphilitic meningitis

Answer 14

• ~1-2 years following initial infection
• Cranial mononeuropathies
• Hydrocephalus
• Focal hemispheric signs

Question 15

Syphilitic cerebrovascular-meningovascular disease

Answer 15

• 5-7 years after infection
• Ischemia, particularly in MCA
• Meningeal irritation
• Can present w/ stroke in evolution

Question 16

Tabes dorsalis typically occurs ___ following initial infection with syphilis

Answer 16

Tabes dorsalis typically occurs >10 years following initial infection with syphilis

Question 17

Gummatous neurosyphilis

Answer 17

• Form of neurosyphilis that may occur much earlier following syphilis infection
• Effectively a gumma that is compressing the brain – as such it occurs as part of secondary syphilis
• Presents like any brain tumor

Question 18

Considerations in the ddx for tabes dorsalis

Answer 18

• Subacute combined degeneration due to B12 deficiency
• Multiple sclerosis
• Lyme disease

Question 19

__ on EMG is often lost in neurosyphilis

Answer 19

H reflex on EMG is often lost in neurosyphilis

Due to damage of the DRG

Question 20

On EMG testing, __ are selectively affected in neurosyphilis. __ strongly suggests against a diagnosis of neurosyphilis.

Answer 20

On EMG testing, sensory neurons are selectively affected in neurosyphilis. Motor neuron abnormalities strongly suggest against a diagnosis of neurosyphilis.

Question 21

Treatment of neurosyphilis

Answer 21

• Standard therapies
  
  • High-dose IV aqueous penicillin G for 10-14 days
  • If penicillin allergic, doxycycline for 28 days AND ceftriaxone for 14 days should be administered together
  • If pregnant AND penicillin allergic, desensitize to penicillin, then treat with penicillin
• If symptoms persist, retreat
• CSF studies should be re-examined after completion of therapy and demonstrate a drop in WBC count, protein, and IgG synthesis

Question 22

Neurosyphilis in patients with HIV

Answer 22

Neurosyphilis may present much more rapidly in patients with coinfection of syphilis and HIV

As such, take into account risk factors for HIV when considering your DDx. Also, if a patient has clear onset of neurosyphilis with an accelerated timecourse, you should test for HIV.

Question 23

Patients with neurologic symptoms and a history of syphilis should be assumed. . .

Answer 23

. . . to have neurosyphilis until proven otherwise

Question 24

Syphilitic aseptic meingitis

Answer 24

Occurs as a chronic infection

Onset 1-2 years after primary infection

May involve headaches, cognitive changes, and cranial nerve abnormalities