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Foundations > CNS Infections > Flashcards

CNS Infections Flashcards

1
Q

What are the causes of CNS infections

A
  • bacteria
  • viruses/aseptic
  • aseptic/meds
  • fungi
  • parasites
  • prion
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2
Q

define meningitis

A

inflammation of membranes surrounding the brain

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3
Q

define encephalitis

A

inflammation of brain parenchyma

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4
Q

define myelitis

A

inflammation of spinal cord

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5
Q

What determines the presentation of meningitis/encephalitis

A

the location of the infection, not the organism

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6
Q

Which organisms cause acute onset meningitis

A

viruses, aerobic bacteria

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7
Q

Which organisms cause subacute or chronic meningitis

A

anaerobic bacteria, tuberculosis, fungi

T. pallidum

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8
Q

Describe the pathophys of meningitis/encephalitis

A

organism enters body via GI, resp, skin nidus. Replication begins. Travels to CNS by blood, peripheral nerves, bone and penetrates the blood/CSF barrier, infects endothelial cells of cerebral blood vessels, or through infected emboli.

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9
Q

Describe the hallmarks of bacterial meningitis

A
  • abrupt, acute inflammatory process
  • acute onset of severe headache, fever, stiff neck
  • multiple infectious causes
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10
Q

What are the 2 common organisms in bacterial meningitis

A
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11
Q

What is the most common cause of bacterial meningitis

A

staphylococcus pneumoniae among adults and newborns

neisseria meningitidis on college campuses

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12
Q

What are the goals of a work-up for bacterial meningitis

A

start IV, start abx, get lumbar puncture within 60 mins

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13
Q

Describe the big 3 symptoms for bacterial meningitis

A

- fever, stiff neck, altered mental status

  • also HA, fever, N/V, pain
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14
Q

What signs on physical exam would potentially be seen in bacterial meningitis

A
  • fever
  • nuchal rigidity to neck flexion
  • kernig sign
  • brudzinksi sigh
  • rash (n. meningitidis)
  • do lumbar puncture
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15
Q

What might be on a DDx for bacterial meningitis

A
  • non-infectious meningitis
  • stroke
  • encephalitis
  • vasculitis
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16
Q

What labs are done for bacterial meningitis

A
  • WBC & ESR high
  • BMP to assess electrolytes and kidney
  • blood cultures to ID organism
  • CSF analysis through LP (ID organism, susceptibility testing)
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17
Q

Describe LP opening pressure

A
  • rate of production and drainage of CSF
  • measured over 1 min with manometer while obtaining LP sample
    - increased indicates infection, inflammation, hemorrhage
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18
Q

How to interpret LP results

A
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19
Q

What are some AEs of a LP

A
  • headache
  • CSF leak
  • pain
  • iatrogenic menigitis
  • nerve root injury
    - uncal herniation
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20
Q

Who should get a CT prior to a LP

A
  • immunocompromised
  • hx CNS disease
  • new onset seizure
  • papilledema
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21
Q

Describe papilledema

A
  • increased pressure in or around brain causing swelling of the optic nerve inside the eye, blurring of optic disc, enlarged retinal veins
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22
Q

What are some contraindications of an LP

A
  • brain shift seen on CT
  • clinical signs of impending herniation
  • thrombocytopenia
  • spinal epidural abscess
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23
Q

What is the order of operations in bacterial meningitis management

A
  • blood cultures
  • empiric abx therapy
  • CT if needed
  • LP if not contraindicated
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24
Q

Describe the empiric antimicrobial treatment for bacterial meningitis

A
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25
Q

Should steroids be used with treatment of bacterial meningitis

A

Recommended only in high income countries (dexamethasone)
- consider for adults and children especially with S. pneumo

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26
Q

Describe the mortality of bacterial meningitis

A

10% overall but varies by organism (higher for s. pneumo)

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27
Q

What are some complications of bacterial meningitis

A
  • CN palsy
  • focal deficits
  • sensorineural
  • seizures
  • hydrocephalus
  • memory/gait/etc.
28
Q

What is the etiology of aseptic meningitis

A

- viral
- TB, mycoplasma, lyme, fungal
- meds
- CNS lymphoma
- autoimmune

29
Q

What differentiates aseptic from bacterial meningitis

A
  • more benign and self limited
  • lymphocytic cellular response
  • routine bacterial cultures are negative
30
Q

Describe the presentation of viral meningitis

A
  • fever, HA, irritation of meninges, photophobia
  • malaise, muscle aches, N/V, diarrhea
  • mild lethargy
31
Q

What is the etiology of viral meningitis

A

- enteroviroses (coxsackieviruses)
- varicella zoster
- HSV2
- EBV
- arbovirus
- HIV
- influenza or mumps

32
Q

What diagnostic testing is done with viral meningitis

A
  • LP
  • bacterial cultures: negative
  • PCR testing on CSF
  • can culture other sites and do serology
33
Q

define lymphocytic pleocytosis

A

increase in WBCs in the CSF

34
Q

How to treat viral meningitis

A
  • treat symptoms
  • begin as if treating bacterial meningitis if severely ill (acyclovir for HSV, EBV, VZV)
35
Q

Prognosis of viral meningitis

A

super grea
- 1-2 weeks, sometimes develop chronic headaches

36
Q

Who gets admitted with viral meningitis

A
  • elderly
  • immunocompromised
  • uncertain diagnosis
37
Q

Who may be susceptible to TB/fungal meningitis

A
  • malnourished, debilitated, immunosuppressed
  • chronic, weeks/months of feeling unwell
38
Q

What might labs show for TB/fungal meningitis

A

elevated protein and low glucose found in CSF

39
Q

Mortality for TB/fungal meningitis

A
  • 20-50%
  • consult infectious disease
40
Q

What can cause spirochete aseptic meningitis (chronic)

A
  • syphilis
  • lyme
41
Q

What is the etiology of encephalitis

A
  • virus reaching brain by hematogenous route
  • associated with meningitis
  • same organisms involved as viral meningitis
    - neuronal necrosis and lysis of glial cells causing cerebral edema
42
Q

What organisms are common in encephalitis

A
  • epidemic west nile arbovirus
  • HSV1 is most common
  • measles virus
43
Q

describe the presentation of encephalitis

A

abrupt onset of symptoms
- HA
- AMS (obtunded/unresponsive)
- seizures
- hyperreflexia
- +babinski
- focal neuro findings
- no nuchal rigidity, normal kernigs and brudzinski

44
Q

What might be on the DDx for encephalitis

A
  • vascular disease
  • abscess
  • other infection
  • tumor
  • SLE, autoimmune
45
Q

Describe the work up for encephalitis

A
  • EEG: abnormal, shows diffuse bilateral slowing, seizure
  • CSF looks similar to viral meningitis
  • opening pressure: normal or elevated
  • WBC: lymphocyte predominance
  • protein: elevated
  • **CT/MRI normal early on but then may show edema, necrosis, hemorrhage
  • PCR or serologic testing
46
Q

Management of encephalitis

A

Symptomatic care
- ASMs
- hyperventilation and mannitol for increased ICP
- steroids = controversial
- early acyclovir for HSV
- rehab cognitive impairment

47
Q

Prognosis for encephalitis

A

Depends on infectious agent
- Mumps = excellent
- arbovirus = reasonable (15% mortality, up to 25% dementia, seizures, focal deficits)
- HSV, others = poor (20-40% mortality)
- rabies = fatal

48
Q

Describe primary amebic meningoencephalitis (PAM)

A
  • rare, extremely fatal
  • Naegleria fowleri (brain eating amoeba)
  • presents as HA, fever, N/V, meningoencephalitis symptoms
  • death due to brain swelling
49
Q

How can someone get PAM (brain amoeba)

A
  • lives in soil, washes into pond/lakes
  • enters the nose
  • get a good social/travel history
  • swimming, diving, body of water, neti pot, religious nasal cleaning
50
Q

How to treat PAM

A
  • consult ID
  • multi drug, like bacterial meningitis until ruled out
51
Q

Describe a the pathophys of a brain abscess

A
52
Q

What causes brain abscesses

A
  • direct extension after surgery, infections from trauma, hematogenous spread
53
Q

What is the most common organism in brain abscess

A

- bacteriodes fragilis
- staph aureus post trauma
- fungi and parasites in immunocompromised

54
Q

Describe the presentation of brain abscesses

A
  • subacute onset of symptoms from localized brain infection
  • symptoms result from increased intracranial pressure
  • symptoms depend on location in the brain
  • headache, lethargy, intermittent fever, focal/generalized seizure
    - classic triad of headache, fever, focal neuro deficit
55
Q

What is on the DDx for brain abscesses

A
  • bacterial meningitis
  • brain cancer
  • epidural abscess
  • focal encephalitis
56
Q

What is this

A

brain abscess

57
Q

Work up for a brain abscess

A
  • neurosurgical needle aspiration with gram stain and culture
  • EEG often abnormal, localized slowing
  • LP: potentially dangerous
  • blood culture + in 10%
58
Q

Management of a brain abscess

A
  • abx therapy, surgical drainage thru aspiration/excision
  • broad spectrum abx for aerobic and anaerobic coverage (4-8 weeks)
  • mannitol for cerebral edema
  • ASMs
59
Q

Neuro sequelae of brain abscess

A

in 50%
- seizures
- focal deficits

59
Q

Brain abscess prognosis

A
  • mortality significantly better now = 15%
59
Q

What is a prion

A

protein normally made by neurons that is misfolded into abnormal infectious particle that is hard to kill
- can be transmitted thru inoculation or hereditary

60
Q

What are the common forms of prion disease

A
  • CJD (creutzfeldt-Jakob)
  • GSS
  • fatal familial insomnia
  • Kuru
  • bovine spongiform (mad cow)
61
Q

Presentation of prion disease

A

subacute to chronic progressive dementia, fatal of 6 mos - 2 years
- memory loss, impaired judgement, intellectual decline
- myoclonis

62
Q

workup for prion disease

A

Prion present in CSF, brain, pituitary, peripheral nerves
- hard to diagnose
- labs mostly normal

63
Q

Steps of diagnosing and treating CNS infections

A

Foundations (9 decks)

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