CNS infections Flashcards

1
Q

What are the four questions that should be answered with CNS infections?

A
  • Acute or chronic
  • Etiology
  • Work up?
  • Treatment
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2
Q

What are the major non-infectious etiologies of CNS problems?

A
  • Neoplasia
  • Collagen vascular disease
  • Meds
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3
Q

What is the best way to assess for infectious CNS infections?

A

Spinal fluid

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4
Q

What is the major confounding factor of spinal glucose levels?

A

Pts has DM

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5
Q

How do you assess spinal fluid glucose levels in the diabetic patient?

A

ratio of serum to CSF should be less than 0.6

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6
Q

What is the normal opening pressure of CSF?

A

50-195 in the lateral decubitus position

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7
Q

What commonly complicates CSF fluid samples?

A

Prior abx treatment

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8
Q

What is a high CSF opening pressure most commonly seen in? Why?

A

Cryptococcal meningitis

Occludes the arachnoid villi

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9
Q

india ink stain = ?

A

Cryptococcal neoformans

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10
Q

True or false: with elevated intracranial pressure from cryptococcus infx, doing an LP is both diagnostic and therapeutic

A

True

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11
Q

When is flow cytology useful with CSF samples?

A

Diagnosing lymphomas

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12
Q

What is xanthochromia?

A

Yellowish supernatant of CSF that is a result of RBC lysis, indicated the presence of oxyhemoglobin, methemoglobin, and bili

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13
Q

How long does it take for RBCs to breakdown in the CSF to cause xanthochromia? Why is this important?

A

2-4 hours

Means that a traumatic tap will not cause this–this is pathologic

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14
Q

What is the normal WBC count in CSF in children and adults?

A

Both 0-5 /mm^3

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15
Q

What are the three etiologies of elevated WBC in the CSF?

A

Meningitis
Encephalitis
Parameningeal focus

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16
Q

What is the formula for the true WBC in CSF?

A

Actual WBC - (WBC in blood x RBC in CSF/ RBC in blood)

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17
Q

What is pleocytosis?

A

Increased WBC in the CSF

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18
Q

What non-infectious condition can produce a transient CSF pleocytosis?

A

Seizures

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19
Q

White counts in CSF are usually highest in what type of infectious etiology?

A

bacterial

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20
Q

What WBC cell predominates with viral meningitis?

A

Mononuclear

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21
Q

What WBC cell predominates with bacterial meningitis?

A

PMNs

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22
Q

What WBC cell predominates with TB meningitis?

A

Mononuclear

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23
Q

What WBC cell predominates with cryptococcal meningitis?

A

Mononuclear

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24
Q

What is the WBC range for viral meningitis?

A

50-1000

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25
Q

What is the WBC range for bacterial meningitis?

A

1000-5000

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26
Q

What is the WBC range for TB meningitis?

A

50-300

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27
Q

What is the WBC range for cryptococcal meningitis?

A

20-500

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28
Q

What are the glucose levels with viral meningitis?

A

More than 45

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29
Q

What are the glucose levels with bacterial meningitis?

A

Less than 40

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30
Q

What are the glucose levels with TB meningitis?

A

Less than 45

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31
Q

What are the glucose levels with Cryptococcal meningitis?

A

Less than 40

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32
Q

What are the protein levels in viral meningitis?

A

Less than 200

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33
Q

What are the protein levels in viral meningitis?

A

Less than 200

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34
Q

What are the protein levels in bacterial meningitis?

A

100-500

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35
Q

What are the protein levels in TB meningitis?

A

50-300

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36
Q

What are the protein levels in cryptococcal meningitis?

A

more than 45

37
Q

What indicates an abnormal CSF-serum glucose ratio?

A

Less than 0.5

38
Q

What is the cause of CSF hypoglycorrhachia? (3)

A
  • WBCs and bacteria eat it
  • Increased metabolism in brain and spinal cord
  • Lower uptake d/t inhibition of transporters
39
Q

What concentrations of protein in the CSF is considered abnormal?

A

More than 50 mg/dL

40
Q

How do you correct for protein levels with a traumatic LP?

A

Subtracting 1 mg/dL of protein for every 1000 RBCs/mm^3

41
Q

What is usually preferred for CNS infections: CT or MR?

A

MR, since is more sensitive and specific

42
Q

Who should get neuroimaging (2, non-obvious ones only)?

A
  • Increased ICP

- Neonates with enlarging head circumference

43
Q

What are the two major qualities of abx for the treatment of CSF infx?

A
  • Must cross BBB

- bactericidal

44
Q

What quality is better for penetration into the CSF, drugs with: low or high molecular weight

A

Low

45
Q

What quality is better for penetration into the CSF, drugs with: low or high ionizability

A

Low

46
Q

What quality is better for penetration into the CSF, drugs with: low or high Lipid solubility

A

High

47
Q

What quality is better for penetration into the CSF, drugs with: low or high degree of protein binding

A

Low

48
Q

Why are bactericidal abx preferred in the treatment of CSF infx?

A

Usually occur in the immunocompromised host, and immune system is limited here

49
Q

What is the role of corticosteroids for the treatment of meningitis?

A

reduce the inflammatory response of killing bacteria

50
Q

What is the only real time to call a surgeon for CSF infx?

A

If you suspect an abscess

51
Q

What is the most common bacterial cause of meningitis outside of adolescence? When in adolescence?

A

Strep Pneumoniae

Neisseria meningitidis

52
Q

What are the two most common causes of viral meningitis?

A

enterovirus

Herpes

53
Q

What are the noninfectious causes of acute meningitis?

A

Craniopharyngioma

Teratoma

54
Q

Which age ranges does listeria infect more often? Why?

A

Neonates and the elderly

new and old immune systems cannot kill intracellular pathogens well

55
Q

What is the treatment for HiB meningitis?

A

Third gen cephalosporin

56
Q

What is the treatment for Neisseria meningitis?

A

Third gen cephalosporin

57
Q

What is the treatment for Strep pneumoniae meningitis?

A

Vanco + 3rd gen cephalosporin

58
Q

What is the treatment for listeria meningitis?

A

Ampicillin and an aminoglycoside

59
Q

What is the treatment for GBS meningitis?

A

Ampicillin + aminoglycoside

60
Q

What is the treatment for e.coli meningitis?

A

Third gen cephalosporin

61
Q

Meningitis in pts who have recently undergone neurosurgery is commonly caused by what? Why?

A

Coagulase negative Staph species

Part of the normal skin flora

62
Q

Does ceftriaxone treat pseudomonas?

A

no

63
Q

What is the treatment for meningitis with an immunocompromised state?

A

Vanco + ampicillin

64
Q

What is the treatment for meningitis with an basilar skull fracture?

A

vanco + 3rd gen ceph

65
Q

What is the treatment for meningitis with head trauma/neurosurgery?

A

Vanco + ceftazidime

66
Q

Why isn’t picnazo (commonly used in sepsis) used for meningitis?

A

Does not cross the BBB

67
Q

What is the only organism that causes meningitis that is appropriate for steroid used? What is the timeframe that they should be given in?

A

Strep pneumo

Within 15-20 minutes of abx administration

68
Q

What are the two bacterial causes of meningitis that can be treated with abx for 7 days?

A

Neisseria meningitidis

HiB

69
Q

What is the duration of treatment for strep species?

A

2-3 weeks

70
Q

What is the duration of treatment for listeria?

A

over 3 weeks

71
Q

What is the duration of treatment for aerobic gram negative bacilli?

A

3 weeks

72
Q

What is the species of tick that carries borrelia burgdorferi?

A

Ixodes

73
Q

What is the chemical that should be used on clothing to repel ticks?

A

Permethrin

74
Q

What is the rash that occurs with lyme disease? How often does this occur?

A

Erythema migrans

80-90% of the time

75
Q

What are the ssx of neuroborreliosis?

A

Cranial neuropathy
meningitis
motor or sensory radiculoneuropathy

76
Q

What are heart ssx of untreated lyme disease?

A

complete heart block

77
Q

True or false: Even without abx, the immune system will kill borrelia

A

True

78
Q

What percent of patients with lyme disease have arthritis?

A

60%

79
Q

What is the treatment for lyme disease?

A

14-21 days of doxycycline or amox

80
Q

What is normal opening pressure?

A

50-180 cm of water

81
Q

What is the treatment for cryptococcal meningitis?

A

Months of amp B or fluconazole

82
Q

What is the complication from chronic meningitis?

A

Hydrocephalus

83
Q

What are the late ssx of chronic meningitis?

A

Visual changes, confusion, CN involvement, unsteady gait, emesis

84
Q

Why is n/v common with cryptococcal meningitis?

A

Increased ICP

85
Q

What are the top three nonbacterial causes of chronic meningitis?

A

Cryptococcal
Histoplasma
Coccidioidomycosis

86
Q

What are the top three bacterial causes of chronic meningitis?

A

TB
Syphilis
Brucellosis

87
Q

True or false: since aspirated material is usually polymicrobial, then abscesses that form in the body are also polymicrobial

A

True

88
Q

What is the most common encephalitis?

A

Herpes