Infections of the Nervous System

Question 1

Name the meningeal layers, starting from the outer layer)

Answer 1

Dura Mater, Arachanoid, Pia Mater

Question 2

What is CSF produced by and where is it located? What does it contain? What are its functions?

Answer 2

Produced by choroid plexus
Through subarachnoid space - around brain and spinal cord
Similar to blood plasma but less protein and very few cells
Functions: Cushions brain + metabolic support to CNS

Question 3

Define meningitis

Answer 3

inflammation (usually infectious) of the meninges

Question 4

Define Encephalitis

Answer 4

inflammation (usually infectious) of the brain

Question 5

Define Meningoencephalitis

Answer 5

inflammation of the meninges & brain

Question 6

Define Myelitis

Answer 6

inflammation (sometimes infectious) of the spinal cord

Question 7

Define Cerebral abscess

Answer 7

collection of pus in the brain

Question 8

What organisms can cause meningitis?

Answer 8

Neisseria meningitidis (meningococcus)
Streptococcus pneumoniae (pneumococcus)
Enterovirus, VZV, HIV, mumps, measles
Cryptococcus neoformans

Question 9

What organisms can cause Encephalitis?

Answer 9

HSV, VZV, HIV, arboviruses, rabies

Question 10

What organisms can cause Abscesses?

Answer 10

Mostly Streptococci

Question 11

What are clinical features of CNS infections?

Answer 11

Stiff neck
photophobia
purpuric (non-blaching rash)
fever
reduced consciousness - GCS scale
seizures
confusion
headaches

Question 12

What are the clinical features of Meningococcal infections?

Answer 12

children & young adult, possible outbreaks acute, sepsis, purpuric rash, peripheral gangrene

Question 13

What investigations would you carry out to test for CNS infections?

Answer 13

FBC
Inflammatory markers (e.g. CRP)
Renal function (Us+Es)
Coagulation tests (APTT+PT)
Blood cultures x 2
Blood for PCR tests
HIV test?
Head CT if raised ICP
Lumbar Puncture (LP) - microscopy + microbiology

Question 14

How would you investigate for infections via a lumbar puncture (LP)?

Answer 14

Measure opening pressure & describe appearance
Samples 1 + 3 sent for microscopy & microbiology RCC / WCC & differential / organisms / PCR tests

Sample 2 sent for biochemistry
Protein / Glucose (with blood glucose to compare)
Additional tests required for M. tuberculosis & Cryptococcus

Question 15

If the CSF extracted from a patient is cloudy, what does that indicate?

Answer 15

bacterial meningitis

Question 16

In bacterial CNS infections, what is the WCC, major WBC type, protein and glucose levels?

Answer 16

WCC - high
Major WBC type - neutrophils
Protein - high
Glucose - low

Question 17

In viral CNS infections, what is the WCC, major WBC type, protein and glucose levels?

Answer 17

WCC - slightly high
Major WBC type - lymphocytes
Protein - slightly high
Glucose - normal

Question 18

In TB infections, what is the WCC, major WBC type, protein and glucose levels?

Answer 18

WCC - high
Major WBC type - lymphocytes
Protein - very high
Glucose - low

Question 19

How would you treat a patient that you suspect has bacterial meningitis?

Answer 19

Ceftriaxone + IV Dexamethasone

Question 20

How would you treat a patient that you suspect has listeriosis?

Answer 20

IV Amoxicillin

Question 21

How would you treat a patient that you suspect has viral encephalitis?

Answer 21

IV Aciclovir