Central Nervous System Flashcards

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1
Q

What is the CNS protected by?

A
  • bone and membrane layers

brain is protected by the skull, spinal cord is protected by the vertebral column

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2
Q

If bacteria are crossing the BBB, they are likely to cause _____

A

encephalitis

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3
Q

If bacterial are crossing the CSF, they are likely to cause ____

A

meningitis

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4
Q

What are the three ways that microbes can cross the BBB?

A
  1. growing across, infecting the cells that compromise that barrier
  2. being passively transported across in intracellular vacuoles
  3. being carried across by infected white blood cells
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5
Q

What is the bodies response to being invaded in the CSF?

A
  • and increase in lymphocytes and monocytes in the CSF
  • a slight increase in protein also occurs, with the CSF remaining clear (this is termed aseptic meningitis)
  • the response to pyogenic bacteria shows a more rapid increase in polymorphonuclear leukocytes and proteins, so that the CSF becomes visibly turbid (this is called septic meningitis)
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6
Q

____ meningitis is more severe but less common

A

Bacterial

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7
Q

What are the 3 key pathogens that are known to cause bacterial meningitis ? What do these three bacteria have in common?

A
  • neisseria meningitidis and streptococcus pneumoniae
  • haemophilis influenzae
  • these three bacteria all possess a capsule, allowing them to be virulent
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8
Q

Neisseria meningitiditis is a gram ____ diplococci

A

negative

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9
Q

In meningococcal meningitis, the infection can be asymptomatic when the bacteria possess ____ and attach to the epithelium of the _____

A

pili

nasopharynx

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10
Q

About ___% of the population is a carrier of meningococcal meningitis, with higher carrier rates during epidemics

A

20

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11
Q

People that are possessing specific complement dependent bacterial ____ to capsular antigens are protected against invasion

A

antibodies

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12
Q

Individuals that have ____ complement deficiency are more susceptible to infection

A

C5-C9

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13
Q

Young children who have ______ and adolescents who have ______ are at the greatest risk of contracting meningococcal meningitis

A
  • lost maternal Abs

- never encountered infecting serotypes

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14
Q

Person to person spread takes place via ______

A

droplet infection due to overcrowding and confinement (in prisons, college dorms, military barracks)

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15
Q

When in the year is the peak time for meningitis?

A
  • winter/early spring - carrier rates here are between 60-80%
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16
Q

What is the incubation time for meningitis?

A
  • 1-3 days
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17
Q

What are the symptoms of sudden onset meningitis?

A
  • headache, sore throat, drowsiness, fever, stiff neck, hemorrhagic skin rash (indicates septicemia)
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18
Q

What is the mortality rates in treated meningitis individuals?

A
  • treated is 10%
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19
Q

What serotypes do routine childhood vaccinations vaccinate for?

A

Serotypes A, C, Y and W135 (routine childhood vaccination)

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20
Q

What tests are used to diagnose meningitis?

A
  • essentially a gram stain of CSF, culture or white blood cell counts
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21
Q

There are 6 different serotypes of _____, a-f, that are distinguishable serologically by their capsular polysaccharides

A

Haemophilus influenzae B

22
Q

Haemophilus influenzae B leads to what disease?

A
  • haemophilus meningitis
23
Q

_______ is a resident of the respiratory tract of children. Maternal antibodies protect the child until they are about 3-4 months old, but then the antibodies wane and there is a _____ before the child develops their own antibodies

A
  • H. influenzae B

- window of susceptibility

24
Q

What is the incubation period of Haemophilus influenzae?

A

5-6 days

25
Q

Haemophilus meningitis is ___ fatal than meningococcal and pneumonococcal meningitis

A

less

26
Q

What are the most common effects of haemophilus meningitis?

A
  • less fatal

- but will have symptoms of hearing loss, delayed language development, mental retardation and seizures

27
Q

The vaccine for haemophilus meningitis is HiB and is suitable for patients over the age of ___

A

2 months

28
Q

Pneumonococcal meningitis is carried in the ____ of many healthy people

A

throats

29
Q

Pneumococcal meningitis is common in which 2 demographics?

A

children and the elderly

- can also be in those with sickle cell disease and those with head trauma

30
Q

The susceptibility of a pneumonococcal meningitis is associated with what?

A
  • low level of capsular antibodies in the blood
  • the antibody opsonizes the organism and promotes phagocytosis
  • this protects the host form invasion
31
Q

The mortality rate of pneumonococcal meningitis is _____ than that of H influenzae and N meningitidis

A

higher

32
Q

What is the main bacteria that is responsible for pneumonococcal meningitis?

A

Strep. pneumoniae

33
Q

What is the vaccine that is most used for pneumonococcal meningitis?

A
  • heptavalent protein-conjugate (2-23 months and immunocompromised)
  • 23 valent for children
34
Q

What is the most common type of meningitis?

A
  • viral meningitis
35
Q

What are the general symptoms of meningitis?

A
  • mild symptoms
  • headache, fever, light sensitivity (photophobia)
  • complete recovery is typical here
36
Q

What is a diagnosis of viral meningitis based on?

A
  • viral genome detection (PCR)
37
Q

What kind of viruses are often the cause of viral meningitis?

A
  • enteroviruses
38
Q

What is encephalitis?

A
  • inflammation of the brain parenchyma
39
Q

What is encephalitis usually caused by?

A
  • typically a virus
40
Q

What are the most common symptoms of encephalitis?

A
  • cerebral dysfunction

- abnormal behaviour, seizures, nausea, fever, and vomiting

41
Q

What is the virus that most often causes encephalitis?

A
  • Herpes Simplex Virus
42
Q

How do neonates most often contract encephalitis?

A
  • passage down the birth canal of a female that is shedding HSV-2
43
Q

How do older children and adults most often contract encephalitis?

A
  • HSV-1 viral replication in nerves in the skull (trigeminal ganglia) and the infection spreading back to temporal lobe of the brain
44
Q

There is a __% fatality rate of encephalitis if it is not treated

A

70

45
Q

What is the general treatment for encephalitis?

A
  • antiviral treatment for 21 days
46
Q

What are the most common symptoms of poliovirus encephalitis?

A
  • 1-4 days of fever, sore throat, malaise, followed by signs of meningitis
  • can lead to paralysis due to the effect on motor neurons
47
Q

What are the two main carriers of west nile virus? What are the two incidental hosts?

A
  • birds and culicine mosquitoes are the carriers

- humans and horses are the incidental hosts

48
Q

What caused the spread of west nile virus to NA?

A
  • migrating birds (previously only in the middle east and africa)
49
Q

What are the main ways of diagnosing a west nile virus infection?

A
  • RNA detection of IgM Ab in sera/CSF
50
Q

What is the only way to control a west nile virus infection?

A

mosquito control