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Neuro Exam 2 > Neuro Infectious Diseases > Flashcards

Neuro Infectious Diseases Flashcards

1
Q

overview of CNS infections

A

*life-threatening problems with high associated mortality and potential long-term morbidity
*presentation may be acute, subacute, or chronic
*clinical findings dictated by anatomic site(s) of involvement, infecting pathogen, and host response

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2
Q

anatomic structures that may be involved in CNS infections

A

-meningitis (inflammation of meninges)
-encephalitis (inflammation of brain)
-brain abscess/cerebritis (focal pocket of infection in the brain)
-epidural/subdural empyema (pocket of purulence in a space; can be in brain or spinal cord)

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3
Q

routes of CNS infection

A
  1. blood-borne spread from remote site of infection or site of mucosal colonization
  2. direct spread from contiguous focus
  3. access via anatomic defects
  4. direct inoculation (trauma, transplantation of infected tissues)
  5. entry via intraneural pathway (ex. herpesviruses)
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4
Q

blood-borne spread - route of CNS infection

A

*most common route of entry for CNS infections
1. microbes enter blood from sites of remote infection (i.e. lungs) or mucosal colonization (i.e. nasopharynx) and invade CNS
2. organisms must avoid host defenses in blood, be able to attach to neuroendothelial cells, and penetrate the blood-brain barrier

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5
Q

examples of common organisms that cause CNS infection due to blood-borne spread

A
  1. S. pneumoniae***
  2. N. meningitidis
  3. H. influenzae
  4. enteroviruses (Coxsackie, polio, echovirus)

NOTE - encapsulated bacteria have better evasion strategies to avoid host defenses

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6
Q

direct (contiguous) spread - route of CNS infection

A

organisms penetrate CNS from contiguous focus of active infection (sinusitis, dental abscess, osteomyelitis of skill base)

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7
Q

examples of common organisms that cause CNS infection due to direct/contiguous spread

A
  1. S. pneumoniae***
  2. H. influenzae
  3. alpha-streptococci
  4. anaerobes
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8
Q

anatomic defects as a route of CNS infection

A

*organisms take advantage of breaches in physical barriers to enter CNS
*defects may be traumatic, surgical, or congenital in origin
*examples include basilar skull fractures, neurosurgical wounds, and dermal sinus tracts

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9
Q

examples of common organisms that cause CNS infection due to anatomic defects

A

S. pneumonia***

others include H. flu, alpha strep, and anaerobes

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10
Q

factors that make the CNS an immunologically compromised organ system

A
  1. no intrinsic lymph node-lymphatic system
  2. restricted mobilization of traditional host defense components (PMNs, immunoglobulins) due to the blood-brain barrier
  3. restricted entry of antimicrobial agents due to relative impermeability of cerebrovasculature
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11
Q

time course of bacterial CNS infection

A

acute (hours to a couple days)

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12
Q

time course of viral CNS infection

A

subacute (several days)

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13
Q

time course of other (fungal, etc) CNS infections

A

subacute to chronic

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14
Q

CSF response of bacterial CNS infection

A

purulent (neutrophilic) CSF response

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15
Q

CSF response of viral CNS infection

A

lymphocytic CSF response

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16
Q

important bacterial causative organisms of CNS infections

A

strep pneumo
n meningitidis
listeria monocytogenes
strep agalactiae (esp in neonates)

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17
Q

important viral causative organisms of CNS infections

A

enteroviruses
HSV and other herpesviruses
arboviruses (west nile, etc)

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18
Q

important other causative organisms of CNS infections

A

mycobacterium tuberculosis
treponema pallidum (syphilis)
cryptococcus neoformans
coccidioides immitis
toxoplasma gondii

19
Q

important microbial factors in pathogenesis of CNS infections

A

-capsules that resist phagocytosis
-IgA protease that inactivates IgA immunoglobulin at mucosal surfaces
-resistance to natural killing activity of serum
-fimbria/pili that attach to endothelial cells
-tropism for neural tissues

20
Q

common bacterial pathogens in neonates (< 1 month)

A
  1. group B strep
  2. E. coli
  3. listeria monocytogenes
21
Q

common bacterial pathogens in children (1 month - 20 years)

A

1 = N. meningitidis
2 = S. pneumoniae

22
Q

common bacterial pathogens in adults (> 20 years)

A

1 = S. pneumoniae

#2 = N. meningitidis
#3 = listeria monocytogenes (esp. age 50+ or immunocompromised patients)

23
Q

exam tipoff for CNS infections: Summer/Fall

A

arboviruses & enteroviruses

24
Q

exam tipoff for CNS infections: siblings with meningitis

A

1 = N. meningitidis
# 2 = H. influenzae

25
Q

exam tipoff for CNS infections: swimming in freshwater lake/rapids

A

amoebaes (Naegleria fowleri)

26
Q

exam tipoff for CNS infections: handling rodents

A

lymphocytic choriomeningitis virus (LCMV)

27
Q

exam tipoff for CNS infections: exposure to pigeons

A

cryptococcus

28
Q

exam tipoff for CNS infections: exposure to other people with TB or TB-endemic area

A

M. tuberculosis

29
Q

exam tipoff for CNS infections: prior meningitis

A

S. pneumoniae

30
Q

exam tipoff for CNS infections: head trauma

A

1 = S. pneumoniae

other: gram neg rods, staph aureus

31
Q

“classic findings” of CNS infections

A

*fever, headache, meningismus, altered mental status [2 of 4 present in ~95% of patients]
other: exanthems (rash), contiguous foci of infection, focal neurological signs (esp palsies of CN 3, 4, and 6)

32
Q

Kernig’s sign for nuchal rigidity

A

*Kernig = Knee (K & K)
1. flex the knee and hip in a 90 degree angle
2. slowly extend the knee
3. sign considered present if resistance or pain (in back, neck, or head) occurs

33
Q

Brudzinki sign

A
  1. bring chin to chest
  2. sign considered present if this causes flexion of hips
34
Q

what is the single most important diagnostic test in patients with suspected CNS infection

A

LUMBAR PUNCTURE for analysis of CSF

note - also obtain blood cultures for all pts

35
Q

contraindications for lumbar puncture

A

-cellulitis overlying LP site
-increased ICP (stupor/coma, papilledema)
-trauma/mass involving lumbar vertebrae
-thrombocytopenia/bleeding diathesis

36
Q

how do we evaluate the CSF from lumbar punctures

A

-color/clarity
-cell counts/WBC and differential
-chemistries (protein + glucose)
-stains and smears (gram)
-cultures (bacterial)
-multiplex PCRs/antigen screens (if pt has WBCs present)

37
Q

CSF profile for BACTERIAL infections of CNS

A

neutrophilic + LOW glucose (purulent)

38
Q

CSF profile for VIRAL infections of CNS

A

lymphocytic + NORMAL glucose

39
Q

CSF profile for OTHER (TB or fungal) infections of CNS

A

lymphocytic + LOW glucose

40
Q

empiric treatment for bacterial meningitis

A

vancomycin + 3rd generation cephalosporin +/- ampicillin

notes:
vanco is for drug resistant strep
cephalosporin is for S. pneumo, N. meningitidis, H. flu
ampicillin covers for L. monocytogenes

41
Q

what is the most common type of meningitis

A

aseptic (viral) meningitis

42
Q

treatment for viral/aseptic meningitis

A

usually supportive and symptomatic only

43
Q

viral encephalitis - common etiologies

A

HSV encephalitis, enteroviruses, and arboviruses

44
Q

principles of management for CNS infections

A

*prompt decision-making is essential (once dx is considered, start antibiotics ASAP)
*obtain CSF (unless contraindicated)
*use cidal antimicrobial therapies with good CNS penetration
*add steroids with suspected bacterial meningitis
*isolate pts with N. meningitidis

Neuro Exam 2 (24 decks)

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