75. CNS Infections

Question 1

What are the different manifestations and causes of neurocystocercosis?

Answer 1

Consumption of food/water contaminated with human feces = ingest eggs - become cysts in CNS

consume raw/undercooked pork = ingest cysts - become tapeworms

Question 2

Pathogenesis of Meningitis (3)

Answer 2

1. Hematogenous Dissemination: Bacteremia to choroid plexus and crosses BBB (no humoral immunity in subarachnoid space)
2. Contiguous Spread: from sphenoid sinusitis to cavernous sinus (cavernous sinus thrombosis and meningitis)
3. Neuronal Transmission: reactivation/spread of HSV 2 from sensory root ganglia - follow axons to subarachnoid space (aseptic meningitis)

Question 3

CP, CSF findings of Bacterial Meningitis

Typical Bacteria involved

Answer 3

TRIAD of FEVER, STIFF NECK, HA

CSF: high proteins, low Glucose, high WBC, high PMNs

S. pneumonia - G+ lancet shaped diplococci
N. meningitidis - G- diplococci
Listeria monocytogenes - G- rods in chains

Question 4

Aseptic Meningitis

• etiology
• CP
• CSF findings

Answer 4

ENTEROVIRUS (other: arbovirus, west nile virus, HSV 2, HIV, Syphilis)
CP: photophobia, headache, fever (no focal neuro sx)
CSF: low protein, normal glucose, high WBC, high lymphs

Question 5

Subacute/Chronic Meningitis

• etiology
• CP
• CSF findings

Answer 5

TB, Syphilis, Sarcoidosis, Neoplasm, Fungus
CP: sx for weeks
CSF: high protein, low glucose, high WBC, high lymphs

Question 6

Main cause of Encephalitis

• etiology
• sx
• dx
• tx
• pathogenesis

Answer 6

HSV 1 Encephalitis
- fever, FOCAL encephalopathy (focal neuro sx)
-dx: CSF HSV PCR
- tx: ACYCLOVIR ASAP
Path: Reactivation of latent HSV in trigeminal nerve root ganglion - ascends via retrograde spread to temporal cortex/limbic system - spreads cell-to-cell causing necrosis

HSV 1 -> Poor prognosis encephalitis
HSV 2 -> benign, recurring meningitis

Question 7

Pathogenesis of Encephalitis

CP of Encephalitis

Answer 7

1. Hematogenous - from resp tract, GI, subQ tissue
2. Neuronal Transport

CP: fever, headache, altered consciousness

Question 8

Brain Abscess

• pathogenesis
• CP
• Dx (what not to do)
• Etiology
• tx

Answer 8

PG: Hematogenous spread (follows infarction micro/macro of brain) - usually in grey/white junction [can be by contiguous spread following trauma]
CP: TRIAD - fever, HA, focal neuro deficit (due to location)
Dx: MRI > CT (dark center, enhanced rim) - NO LUMBAR PUNCTURE (risk herniation)
E: many types depending on source
tx: drainage and BROAD ABx (cultures often miss some pathogens)

Question 9

Spinal Epidural Abscess

• sx
• late signs

Answer 9

Back pain, focal spinal tenderness, fever

late: LE weakness, loss of bladder control

Question 10

Ciguatera Fish Poisoning

• what is the toxin
• sx
• where?

Answer 10

Foodborn toxin
Ciguatoxin - thermostable (cooking doesn’t help) Na Channel Activator produced by dinoflagellate Gambierdiscus (in reef fish)
sx: N/V, numbness, itching, hot/cold sensitivity, dizziness, weakness (varies by amount consumed, can last weeks-mo)
where: increasing worldwide due to climate change and water temps get warm