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Term 5: Infectious Disease > 6/8- Meningitis and Encephalitis > Flashcards

6/8- Meningitis and Encephalitis Flashcards

1
Q

What is meningitis (def)?

A

Diffuse inflammatory process involving the leptomeninges of the brain and spinal cord

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2
Q

Routes of acquisition of meningitis?

A
  • Hematogenous
  • Direct extension (from bad infection)
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3
Q

What is the mortality rate for meningitis in the US?

What has been responsible for 55% decrease?

A

~15% (500 deaths/year)

Decrease with the Hib/pneumococcal vaccine

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4
Q

What age group(s) have highest incidence of disease?

A

(Per 100,000)

  • Under 2 mo: 80.7
  • 2-23 mo: 6.9
  • 2-10 yo: 0.6
  • 11-17 yo: 0.43
  • > 65 yo: 1.92
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5
Q

What comprises the leptomeninges?

A
  • Arachnoid mater
  • Pia mater (includes subarachnoid space that is typically filled with CSF)

Inflammation of these tissues is what causes the stiff neck

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6
Q

Process of hematogenous dissemination?

What causative organisms?

A

Hematogenous dissemination:

  • Colonization (e..g attach to nasopharyngeal epithelium)
  • Local invasion
  • Bacteremia (through mucosa -> bloodstream)
  • Meningeal invasion (crossing BBB)
  • Bacterial replication (e.g. subarachnoid space)
  • Subarachnoid inflammation

Ex) pneumococcus, N. meningitides

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7
Q

Why are younger children/neonates more susceptible to meningitis?

A

Immune systems aren’t as developed

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8
Q

What groups are especially susceptible to hematogenous dissemination?

A

Age-related:

  • Peak 6-24 mo
  • Increased in neonates and elderly
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9
Q

When does Neisseria meningitidis invade the blood stream?

A
  • First 2 wks after colonization (before Abs develop)
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10
Q

What are risk factors for hematogenous dissemination (esp. N. meningitidis)?

A
  • Viral-illness (esp influenza)
  • Smoking (active and passive)
  • Drinking

These compromise nasal mucosa (?)

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11
Q

What different mechanisms underly host deficiencies?

A
  • Asplenia: functional, congenital, acquired
  • Antibody dysfunction: congenital, acquired (HIV), prior to natural acquisition (under 2 yo), or decline with age
  • Complement deficiency: physiological decrease in newborn or terminal component deficit
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12
Q

What anatomical defects predispose one to meningitis? By what mechanism?

A

Congenital:

  • Dermoid sinus
  • Myelomeningocele

Acquired:

  • Trauma
  • Neurosurgery
  • Tumors

These cause meningitis my direct extension

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13
Q

What is this?

A

Sacral dermoid sinus tract

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14
Q

What is this?

A

Occipital dermoid sinus tract

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15
Q

Direct extension can occur with what conditions?

A

Parameningeal focus:

  • Sinusitis
  • Otitis media
  • Osteomyelitis of the skull or vertebral bones
  • Intracranial foci (brain abscesses)
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16
Q

Pathophysiology of meningitis in neonates (steps)?

A
  • Source: maternal genital tract
  • Aspiration of amniotic fluid
  • Lung and/or bloodstream infection
  • Meningeal invasion
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17
Q

What bacterial products cause inflammation? Results in what?

A

Inflammatory bacterial products:

  • Endotoxin
  • Teichoic acid
  • Peptidoglycans

Results in inflammatory mediator release:

  • TNF
  • Interleukins (IL-1)
  • Arachidonic acid
  • Metabolites
  • Platelet-activating factor
  • Interferons
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18
Q

Overall pathophysiology of inflammatory process in meningitis?

A
  • Bacterial products promote release of inflammatory mediators

Inflammatory factors cause (separately and interplay):

  • Activation of leukocytes
  • Endothelial injury
  • Coagulation cascasde

Results in:

  • Cytotoxic and interstitial edema -> increased ICP
  • Increased BBB permeability -> vasogenic edema
  • Thrombosis -> decreased cerebral blood flow
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19
Q

Clinical-Pathologic correlates (meningitis):

___ -> headache, stiff neck (meningeal signs)

___ -> altered consciousness, SIADH, respiratory depression

___ -> ocular palsies, deafness

___ -> focal seizures, focal deficits

___ -> signs of increased cranial pressure

A

Clinical-Pathologic correlates:

Piaarachnoiditis -> headache, stiff neck (meningeal signs)

Subpial toxic encephalopathy -> altered consciousness, SIADH, respiratory depression

Inflammatory or vascular involvement of CNs -> ocular palsies, deafness

Thrombosis of meningeal vessels -> focal seizures, focal deficits

Hydrocephalus -> signs of increased cranial pressure

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20
Q

What is this?

A

(T1 MRI with contrast)

  • Frontal subdural hygromas (arrows)
  • Also enhancing left thalamic infarction 2ndary to penetrating artery spasm (arrowhead)

This pt has pneumococcal meningitis

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21
Q

What is this?

A

Suppurative meningococcal meningitis

  • Subarachnoid space is filled with neutrophils
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22
Q

What is the classic triad (in kids and adults) for diagnosing meningitis? Other manifestations?

A
  • Fever
  • Nuchal rigidity
  • Change in mental status

Others:

  • Photophobia
  • Seizures
  • Focal neurological deficits
  • Petechiae/purpura
  • Brudzinki’s sign (not in neonates)
  • Kernig’s sign (not in neonates)
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23
Q

What is Brudzinski’s sign?

A

Severe neck stiffness causes pts hips and knees to flex when the neck is flexed

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24
Q

What is Kernig’s sign?

A

Severe stiffness of the hamstrings causes an inability to straighten the leg when the hip is flexed to 90’

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25
Q

Lumbar puncture results in meningitis?

A
  • CSF cell count: high WBC (if bacterial)
  • Glucose: decreased
  • Protein: increased
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26
Q

What can be found on the basic metabolic panel in meningitis?

A

Na to look for SIADH

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27
Q

When would you do diagnostic imaging in the diagnostic process for meningitis?

A

Before LP if focal neurologic deficit

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28
Q

Where is an LP performed?

A

L3/L4 or L4/L5

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29
Q

Normal CSF results?

A

OP: < 20

WBC: < 5

Protein: 15-45

Glucose: 45-80

Stain/Cx: neg/neg

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30
Q

CSF results in bacterial meningitis?

A

OP: Elevated (more than 20)

WBC: > 1,000

Protein: > 100

Glucose: Decreased (under 40)

Stain/Cx: pos/pos

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31
Q

CSF results in viral meningitis?

A

OP: Normal (< 5)

WBC: Elevated but < 300

Protein: Elevated; < 150

Glucose: Normal (45-80)

Stain/Cx: neg/pos (culture or PCR)

32
Q

CSF results in TB?

A

OP: Greatly elevated

WBC: Elevated but < 500

Protein: > 100

Glucose: Slightly decreased (< 50)

Stain/Cx: +/- pos/pos

33
Q

CSF results in abscess?

A

OP: Elevated

WBC: Elevated but < 200

Protein: Elevated

Glucose: Normal (45-80)

Stain/Cx: neg/neg

34
Q

Bacterial meningitis etiology in pediatric age group?

A
  • Early on, GBS dominates (under 2 mo)
  • With older age, more Strep pneumo, Haemophilus and Neisseria
  • In 11-17 yo, 2 main cause (about equal): S. pneumo and Neisserria
35
Q

Bacterial meningitis etiology in adults?

A
  • 18-34 yo: mostly S. pneumo and Neisserria (about equal)
  • In older age groups, predominantly Strep pneumo
  • >65 yo have significant portion of Listeria as well
  • Haemophilus present in all
36
Q

Empiric therapy for meningitis in:

  • Neonates:
  • Infants and kids:
  • Adults:
  • Elderly:
A

Empiric therapy for meningitis in:

  • Neonates: ampicillin and gentamicin
  • Infants and kids: vancomycin and 3rd gen cephalosporin (cefoxitime or ceftriaxone)
  • Adults: vancomycin and 3rd gen cephalosporin (cefotaxime or ceftriaxone)
  • Elderly: vancomycin, 3rd gen cephalosporin and ampicillin (for Listeria)
37
Q

Case 1:

  • 6 hr old male with tachypnea and lethargy
  • Full term male born to a 24 yo mom via spontaneous vaginal delivery
  • Transferred to NICU for respiratory distress
  • LP: WBC 2085 (mostly neutrophils), 10 RBC, protein 245, glucose under 25

What is this?

What is empiric treatment?

A

Differential: bacterial meningitis

  • Group B strep (GBS)
  • Grm - rod (E. coli)
  • Listeria

Empiric treatment: ampicillin + gentamicin

Pt in this case survived but with neurological impairment.. failed end of therapy hearing screen (hearing loss from meningitis, not gentamicin!)

38
Q

What is this?

A

Gram + cocci in chains (Group B strep)

39
Q

Source of GBS in neonatal meningitis?

What is the presentation (timeline)?

A

Source: maternal genital tract

  • Early onset (1st 7 days of life)
  • 80% reduction with intrapartum antimicrobial prophylaxis
  • Late onset (7 d- 3 mo)
40
Q

What percentage of neonates with meningitis have neurologic deficits/sequelae?

A

33-50% of survivors

(85-90% of those affected)

41
Q

What is this?

A

Serratia marcescens meningitis

42
Q

Case 2:

  • 66 yo male with fever and altered mental status
  • Hx of diabetes and HTN
  • Fever x 3 days (also w/ cough and increased work of breathing)
  • CBC with WBC 28,000 (85% neutrophils)
  • CT of the brain without contrast was unremarkable
  • LP with 2540 WBC (90% neutrophils), 350 protein, glucose < 20

Differential diagnosis?

Empiric management?

A

DDx:

  • S. pneumoniae
  • N. meningitidis
  • H. influenzae
  • Listeria
  • Group B strep

Empiric mgmt: Cefotaxime + vancomycin + ampicillin

This ended up being pneumococcal men (Gm stain)

43
Q

What is this?

A

Gm + diplococci = Pneumococcus

44
Q

Streptococcus pneumoniae is the __ most common cause of vaccine-preventable death in the US (__ is the most common cause)

A

Streptococcus pneumoniae is the 2nd most common cause of vaccine-preventable death in the US (Influenza is the most common cause)

45
Q

Pneumococcal meningitis is the __ bacterial cause of meningitis inn what age groups?

A

#1 cause in adults and children

46
Q

Who has an increased risk of pneumococcal meningitis?

A
  • Elderly
  • Alcoholics
  • SCD
  • HIV
  • Trauma
  • Cochlear implants
47
Q

What is the case fatality rate of pneumococcal meningitis? In elderly?

What is common among survivors?

A

Fatality rate: 13-30% (up to 80% in elderly)

Neurologic sequelae common among survivors

48
Q

How can pneumococcal meningitis be prevented?

Given to whom?

A

PCV13 and PPV23 immunization

  • Children: 2-59 mo (< 5 yo)
  • Individuals > 5 yo with high risk conditions
  • Elderly > 65 yo
49
Q

Case 3:

  • 14 yo male with altered mental status, fever
  • Athlete, recurrent influenza-like illness with 3 day Hx of increasing fever, sleepiness, altered mental status
  • Outside hospital: tachypneic, tachycardic, hypotensive
  • CBC with WBC 11 (65% neutrophils)
  • Ceftriaxone given and pt transferred
  • intubated for respiratory failure, inotropic support
  • CSF: WBC 11,000 (96% neutrophils), RBC 250, protein 235, glucose < 20

- Differential diagnosis?

- Empiric mgmt?

A

Differential diagnosis:

  • N. meningitidis
  • S. pneumoniae
  • H. influenzae

Empiric mgmt: ceftriaxone + vancomycin

This ended up being N. meningitidis (Gm stain)

  • Pt slow to wake up, difficulty with speaking and find motor skills (continues to have memory deficits)
50
Q

What is this?

A

Neisseria menigitides (Gm -)

51
Q

What are the primary groups affected by meningococcal disease?

A
  • Infants (6-24 mo)
  • Teens
  • Young adults
  • Outbreaks in military recruits and college students
52
Q

Peak of meningococcal dz in what months?

A

Winter or spring months

53
Q

Prevention of meningococcal dz?

A

Immunization with MCV4 and MenB vaccine

54
Q

What is this?

A

Haemophilus influenzae

55
Q

Characteristics of H. influenzae:

Gm:

Serotypes:

A

Characteristics of H. influenzae:

Gm: negative

Serotypes: 6 different (a-f) of polysaccharide capsule with 95% of invasive dz caused by type B

56
Q

Outcomes of meningitis caused by H. influenzae type B?

A
  • Hearing impairment or neurologic sequelae in 15-30%
  • Case-fatality rate 2-5% despite effective antimicrobial therapy
57
Q

Complications of meningitis?

A
  • Seizures

Hydrocephalus

  • Infarction
  • Herniation
  • Hearing loss
  • Focal deficits
  • Severe neurologic deficits
  • Death
58
Q

What is encephalitis (def)?

A
  • Presence of inflammatory process in the brain or SC (in association with clinical evidence of neurocognitive dysfunction)

[as opposed to disruption of brain function in absence of direct inflammatory process of the brain parenchyma, as in encephalitis]

59
Q

Pathogenesis of encephalitis?

A
  • Direct hematogenous invasion of organism (resulting in cellular dysfunction or cytolysis causing generalized encephalitis)
  • Extension via neuronal tracts causing focal encephalitis
  • Cytolysis leading to perivascular and parenchymal inflammation and focal necrosis
  • Some infectious agents cause direct endothelial injury resulting in vasculitis and infarction
60
Q

Etiologies of encephalitis?

A

Wide variety of pathogens:

  • Viral infections are the most common infectious etiology (Most coommonly enterovirus and HSV)
  • Bacterial, fungal, and parasites are other infectious etiologies
  • Post-infectious (ADEM)
  • Autoimmune
  • Prion

In many cases (32-75%) etiology remains unknown

61
Q

Viral causes of encephalitis?

A

- HSV 1 and 2

- Enteroviruses (polio, coxsackie, echo)

  • Varicella zoster
  • Ebstein Barr
  • Adenovirus Others (less common)
  • Rabies virus
  • Arboviruses (WEEV, EEEV, VEEV, St.Louis encephalitis, LaCrosse encephalitis, W. Nile virus)
  • Lymphocytic choriomeningitis virus
62
Q

Case 4:

  • 5 week old with fever, altered mental status, and fine pinpoint petechial rash
  • Blood, urine, and CSF studies done
  • SF with 230 WBC, glucose 30, protein 60, negative Gm stain

Differential Dx?

A

Enterovirus

63
Q

Characteristics of enteroviruses?

  • Transmission:
  • Peak incidence (months):
  • Incubation period:
  • Diagnosis:
  • Treatment:
A

Transmission:

  • Fecal-oral
  • Respiratory
  • Fomites
  • Vertically during peripartum period

Peak incidence: June - Oct (all year long in Houston)

Incubation: 3-6 days

Diagnosis: PCR

Treatment: supportive

64
Q

Signs and symptoms of encephalitis?

A
  • Fever, headache, nuchal rigidity
  • Altered consciousness
  • Disorientation, behavioral changes
  • Focal neurologic signs or deficits
  • Seizures
65
Q

What do you want to ask in the detailed Hx if suspect encephalitis?

A
  • Recent illnesses
  • Exposures (i.e. animals)
  • Travel
  • Insect bites
  • Season
66
Q

Diagnostic evaluation of encephalitis includes what?

A
  • Detailed Hx
  • Physical exam
  • Cultures (for bacterial/viral agents)
  • Serology (IgG, IgM)
  • Antigen, DNA, or RNA detection (PCR)
  • Epidemiology investigation
  • Diagnostic imaging
67
Q

Treatment for encephalitis?

A
  • Supportive care
  • Antiviral therapy (acyclovir!)
  • Antibiotic therapy
  • Steroids
68
Q

Case 5:

  • 27 you presents w/ fever, headache, irritability, and difficulty walking
  • 14 days ago, got home from summer camping trip - Multiple mosquito bites
  • On exam, proximal lower extremity weakness and absence of reflexes
  • CSF: 62 WBC (85% lymphocyts), glucose 62, protein 84

Differential diagnosis?

Empiric treatment?

A

DDx:

- Viral meningoencephalitis

—Arboviruses, W. Nile VIrus

—HSV, Enterovirus, EBV, CMV

- Noninfectious etiologies

Empirical treatment: Acyclovir

In this case, saw W. Nile IgM in blood and CSF

69
Q

What is the vector for West Nile Virus (WNV)?

A

Moquito-borne flavivirus

  • Culex species
70
Q

Peak transmission of W. Nile Virus?

A

Late summer and early fall

71
Q

Symptoms (and %) in W. Nile virus?

A
  • Mild febrile illness (20%)
  • Less than 1% with severe neurologic manifestations (meningitis, encephalitis, and acute flaccid paralysis)
72
Q

Case 6:

  • 11 yo male presents with fever, headache, and AMS
  • CSF with 82 WBC, normal glucose, protein 90
  • EEG done for possible seizure activity (Focal EEG with prominent intermittent high amplitude slow waves–delta and theta slowing–and continuous periodic lateralized epileptiform discharges from the R temporal lobe)

Differential diagnosis?

A

Differential diagnosis:

  • Herpes simplex encephalitis
73
Q

What is this?

A

CT scan of pt with herpes simplex encephalitis with temporal lobe changes

74
Q

What is one of the only treatable viral encephalitis etiologies?

Treatment?

A

Herpes simplex virus encephalitis

  • Acyclovir (give to all pts until confirm a diagnosis); early treatment can stop viral replication and improve outcome!
75
Q

Clinical-Pathologic correlates (for meningitis):

Piaarachnoiditis -> ____

Subpial toxic encephalopathy -> _____

Inflammatory or vascular involvement of CNs -> ____

Thrombosis of meningeal vessels -> ____

Hydrocephalus -> ____

A

Clinical-Pathologic correlates:

Piaarachnoiditis -> headache, stiff neck (meningeal signs)

Subpial toxic encephalopathy -> altered consciousness, SIADH, respiratory depression

Inflammatory or vascular involvement of CNs -> ocular palsies, deafness

Thrombosis of meningeal vessels -> focal seizures, focal deficits

Hydrocephalus -> signs of increased cranial pressure

Term 5: Infectious Disease (18 decks)

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