Neurologic Infections

Question 1

What are the cranial meninges?

Answer 1

Three membranes surrounding the brain.

Question 2

What are the three cranial meninges?

Answer 2

1) dura mater (outermost)
2) arachnoid mater
3) pia mater (innermost)

Question 3

Where does the blood-brain-barrier NOT exist?

Answer 3

• vomiting centre in the medulla oblongata (to sample toxins)
• hypothalamus to detect water balance and regulate pH

Question 4

What cell reinforces the blood-brain-barrier?

Answer 4

Astrocytes provide biochemical support to the blood vessels, ensuring they remain very impermeable.

Question 5

What molecules can pass through the BBB?

Answer 5

lipid soluble molecules

Question 6

The different type of neurologic infections are based on ____.

Answer 6

anatomic location and microbe, for example:

• whether it is within the brain or spinal cord
• in the meninges
• viral
• bacterial

Question 7

How do pathogens gain entry to the cranium?

Answer 7

• fracture
• compromised BBB
• extension (ex. infection in middle ear or nostril spreads)
• along an axon

Question 8

What three bacteria usually cause bacterial meningitis and what age groups are they related to?

Answer 8

1) Streptococcus pneumonia - adults
2) Haemophilus influenzae - kids under 5
3) Neisseria meningitidis - youth

Question 9

What predisposes an individual to bacterial meningitis?

Answer 9

• head trauma
• neurological surgery
• congruent infection (ex. sinusitis)
• decreased immunity

Question 10

What happens in bacterial meningitis? What is the pathophysiology?

Answer 10

• bacteria enter
• there is bacterial proliferation
• lysis of bacteria and defense cells
• this triggers inflammation
• inflammation causes purulent exudate, which moves to other tissues (brain surface, into CSF, into spinal cord)
• vasculature, ventricles and subarachnoid space also affected

Question 11

What is the worry with bacterial meningitis?

Answer 11

Inflammation can cause swelling inside a limited space (the cranium) which can increase intracranial pressure and this is life-threatening.

Question 12

What are the manifestations of bacterial meningitis?

Answer 12

• fever
• headache
• nausea and vomiting
• nuchal rigidity, back pain
• positive Brudzinski’s sign
• positive Kernig’s sign

Question 13

How is bacterial meningitis diagnosed?

Answer 13

• history and presentation
• culture and sensitivity
• analyze the CSF (would find increased proteins, neutrophils, pus, decreased glucose)

Question 14

How is bacterial meningitis treated?

Answer 14

• antibiotics

- steroids for the inflammation

Question 15

What else is viral meningitis called?

Answer 15

aseptic meningitis

Question 16

Is viral meningitis more or less severe than bacterial meningitis?

Answer 16

It is usually less severe because it is self-limiting. However there is still a risk of increased ICP.

Question 17

What kind of exudate does viral meningitis produce?

Answer 17

Usually serous exudate.

Question 18

If you do a CSF analysis for viral meningitis what will you find?

Answer 18

• increased lymphocytes
• moderate increase in proteins
• normal blood glucose

Question 19

What are the signs and symptoms of viral meningitis?

Answer 19

• fever
• headache
• nausea and vomiting
• nuchal rigidity, back pain
• positive Brudzinski’s sign
• positive Kernig’s sign

Question 20

How is viral meningitis usually treated?

Answer 20

• treat the symptoms, since it is self-limiting

Question 21

What is encephalitis?

Answer 21

inflammation of the parenchyma in the brain or spinal cord

Question 22

What usually causes encephalitis?

Answer 22

usually caused by one of the following two viruses:

1) herpes simplex type 1
2) arbovirus

Question 23

What is the pathophysiology of encephalitis?

Answer 23

• viral particles enter
• cause localized necrosis (lysis of cells) and hemorrhage
• this causes viral particles to spread, the infection becomes generalized
• this results in edema
• the cell bodies degenerate
• unpredictable course

Question 24

What are the manifestations of encephalitis?

Answer 24

• lethargy (general sign of infection)
• fever, headache, nuchal rigidity
• neural disturbances (seizures, coma… depends on area affected)
• severe neurologic impairment is possible… dementia or epilepsy

Question 25

How long will encephalitis usually last?

Answer 25

2 weeks if the infection is caused by arbovirus

Question 26

How is encephalitis treated?

Answer 26

If it is caused by arbovirus, usually just monitor and avoid complications.

If it is caused by herpes simplex it is more serious and will need aggressive treatment = IV medications, for example acyclovir (an antiviral).

Question 27

What is the mortality rate for encephalitis?

Answer 27

30%