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CNS infections Flashcards

1
Q

What is meningitis?

A
  • swelling and inflammation of the membranes covering the brain and spinal cord
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2
Q

What is encephalitis?

A
  • inflammation of the brain
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3
Q

What is an abscess?

A
  • confined pocket of pus that collects in tissue, organs, or spaces inside the body
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4
Q

Most common epidemiologies of BM by age group?

A 
- newborn-1 month:
Group B strep - 70%
- age 1-23 months:
S. pneumonia - 50%
- age 2-18: N. meningitidis - 60%
- adults to 50: S.pneumo - 60%
- 50 and above S. pneumo
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5
Q

Nosocomial bacterial meningitis epidemiology?

A
  • disease of neurosurgical pts, trauma
  • organisms: E. coli, K. pneumonia, P. auruginosa
    strep, S. aureus, and coag neg staph
    listeria
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6
Q

Impt changes in BM epidemiology?

A
  • decline in Hib
  • increasing incidence of S. pneumo (50+% of cases in US)
  • shift from peds to adult disease
  • increase incidence of ATB resistance organisms esp S. pneumo
    PCN resistance: 35%
    Ceph resistance: 15-20%
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7
Q

Predisposing factors of bacterial meningitis?

host risk factors?

A
  • colonization of nasopharynx (N. menigitidis, S. pneumo, and Hib)
  • invasion of CNS following bacteremia due to localized source
  • direct entry of organisms in CNS from contiguous infection, trauma, neurosurgery, CSF leak or medical device (pacemaker)
  • host risk factors:
    asplenia
    chronic corticosteroid use
    immune comp - HIV or on immunosuppresants
    exposure to someone with meningitis
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8
Q

pathogenesis of meningitis/encephalitis?

A
  • virulence factors of pathogen overcome host defense mechanisms and invade CSF
  • CSF has inadequate humoral immunity so bacteria can multiply to high concentrations
  • bacteria can produce an inflammatory response through inflammatory cytokines
  • leads to vasogenic brain edema, increased ICP resulting in brain ischemia, cytotoxic injury (from bacterial secretions) and neuronal apoptosis
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9
Q

Presentation of bacterial meningitis?

Triad? other sxs?

A
  • duration of sxs 2-3 days sometimes but it can also progress over hours
  • triad:
    fever (95% have over 100.4 temp)
    nuchal rigidity: 88%
    change in mental status (lethargy)
  • other sxs:
    HA
    photophobia
    charcteristic rash (N. meningitidis)
    N/V
    neuro complications: seizures, focal beuro deficits, papilledema
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10
Q

Exanthem of meningitis?

A
  • due to small hemorrhages under body
  • all parts of body are affected
  • rashes don’t fade under pressure (non blanching)
    pathogenesis:
    septicemia
    wide spread endothelial damage
    activation of coag
    thrombosis and platelets aggreg
    reduction of platelets
  • sign of septicemia
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11
Q

What tests are specific to meningitis? What should be included in PE?

A
  • thorough physical exam including complete neuro exam
  • 2 tests that are specific:
    kernig sign: supine position, flex hip and inabilty to allow full extension when hip is flexed
    brudzinski sign: spontaneous flexion of hips during attempted passive flexion of neck
  • also check for passive flexion, extension and rotation of neck
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12
Q

When can meningitis be essentially ruled out?

A
  • if pt has no fever, no neck stiffness, and no alt mental status
  • utility of PE in detecting meningitis not great, if you suspect meningitis strongly consider LP to definitely rule it out
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13
Q

Labs and dx tests for meningitis work up?

A
  • CBC with diff
  • CMP
  • UA
  • blood cultures x 2: 50-75%
  • LP: if delayed or deferred obtain blood cultures and start empiric ab therapy
  • possible CT to r/o mass lesion or other causes of IICP or route of infection
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14
Q

What pts need a head CT b/f LP?

A
  • immunocomp. or impaired cellular immunity
  • hx of seizure w/in 1 wk prior to presentation
  • any of following neuro abnormalities:
  • hx of CNS disease (stroke, lesion, focal infection)
  • alt Level of consciousness
  • papilledema
  • focal neuro deficit
  • pts with these RFs should have CT done to ID possible mass lesions and other causes of IICP
  • over-employed dx modality leads to unnecessary delays in tx and added cost
  • rarely indicated in pt with suspected acute meningitis
  • mandatory in pt with possible focal infection
  • increased sensitivity with contrast enhancement (see cerebral edema)
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15
Q

What is CT in bacterial meningitis used for? Indicated in what pts?

A
  • used to ID CIs to LP and complications that reqr prompt neurosurgical intervention such as sx hydrocephalus, subdural empyema, and cerebral abscess
  • indicated in pts who have evidence of head trauma, sinus or mastoid infection, skull fracture and congenital anomalies
  • may ID cerebral edema, effusion, hydrocephalus, abscess
  • may reveal cause of infection
  • may provide normal findings
  • dx of acute BM isn’t made on basis of imaging - made by hx, PE and labs!
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16
Q

Is a MRI useful in meningitis workup?

A
  • not generally useful in acute dx
  • very helpful in investigating potential complications developing later in clinical course such as venous sinus thrombosis or subdural empyema
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17
Q

LP findings in bacterial meningitis?

A
  • elevated opening pressure
  • cloudy, purulent appearance
  • leukocytosis (1000-5000 with greater than 80% neutrophils)
  • protein of 100-500 mg/dL
  • glucose of less than 40 mg/dl
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18
Q

Gram stain findings in bacterial meningitis?

A
  • gram + diplococci suggest S. pneumo
  • gram - diplococci suggest N. meningitidis
  • small pleomorphic gram - coccobacilli suggest H flu
  • gram + rods and coccobacilli suggest listeria
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19
Q

Empiric tx for BM?

A
  • mainly aimed at S. pneumo and N, meningitidis:
    cefotaxime (claforan) or ceftriaxone (rocephin)
    + vanco
  • for L monocytogenes (older than 50): ampicillin or PCN G + gentamicin
    alt: TMP-SMX or meropenem
  • nosocomiaL
    cover gram (-) (E.coli, K, pneumoniae and pseudomonas) and gram +
    use ceftazidime (Fortaz) + vanco

*tx time doubled in immunocompromised pts

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20
Q

RFs for drug resistant S. pneumoniae (DRSP)?

A
  • extremes of age
  • recent ATB rx
  • significant comorbid disease
  • HIV infection or other immunodeficiency
  • day care or day care pt/sib
  • recent hospitalization
  • congregate settings (correctional facilities, military, college dorms)
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21
Q

Neuro complications of BM?

CV complications?

A
  • IICP and cerebral edema
  • seizures
  • CN palsies (5-11%)
  • hemiparesis

CV complications (rare):

  • vessel wall irregularities and focal dilatations
  • arterial occlusions
  • focal arterial bleeding
  • venous thrombosis
  • sensorineural hearing loss: greater with s. pneumo as cause
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22
Q

Role of steroids in tx of BM?

A
  • early IV admin of glucocortiocoids has been eval as adjuvant therapy in an attempt to diminish the rate of hearing loss, cerebral edema, and other neuro complications as well as mortality
  • adding dexamethasone 0.15 mg/kg q 6 IV b/f or w/ start of abx reduces mortality and neuro disability in pts with GCS scores of 8-11 and pneumococcal dx
  • must be given early for best results
  • continued for 4 days if gram stain and/or culture consistent consistent with S. pneumoniae
23
Q

Prevention of meningitis?

A
  • avoid sharing anything personal with anyone who could potentially be sick
  • good hand washing/sanitizing

vaccines:
-Hib (routine childhood)
-PCV13 (routine)
-PPSV23 (older children and adults)
-Meningococcal conjugate vaccine (menactra): older children and adults
-serogroup B meningococcal vaccine (Bexsero)
CDC recommends all 11-12 yos be vaccinated with quadrivalent vaccine with booster at 16
- adolescents and young adults may also be vaccinated with serogroup B vaccine at age 16-18 if outbreak or complement component deficiences, fxnl or anatomic asplenia

24
Q

Adults should get quadravelent meningococcal conjugare vaccine (mennactra) if?

A
  • complement deficiency
  • fxnl or anatomic asplenia
  • microbio exposed to N.meningitidis
  • traveling to countries where disease is common
  • part of pop id’d to be at risk b/c of outbreak
  • first year college student living in residence hall
  • military recruit
25
Q

what is aseptic meningitis?

A
  • clinical and lab evidence for meningeal inflammation with neg bacterial cultures, most common cause is enterovirus, but other etiologies: mycobacteria, fungi, spirochetes, parameningeal infections, meds and malignancy
26
Q

Presentation of aseptic meningitis?

A
  • fever
  • HA
  • stiff neck
  • photophobia
  • contrast to BM: aseptic meningitis is self limited course that resolves w/o specific therapy
27
Q

Etiologic agents of aseptic meningitis?

A
  • enterovirus, HSV, HIV, West Nile, varicella zoster, mumps, influenza, lymphocytic chorio-meningis virus (LCM), syphilis, lyme dz, fungal infections, TB, neoplasms of leptomeninges (breast, lung, melanoma, GI), NSAIDs, IVIG, TMP-SMZ
28
Q

Approach to figuring out aseptic meningitis?

A
  • comprehensive hx: travel, exposure, exanthems, drugs
  • if CSF with LP fairly clear, you can observe pt w/o abx
  • if uncertain, start on abx and wait 24-48 hrs for culture results:
    if pt improving and cultures neg then abx can be stopped
    if pt not improving and cultures neg may need to repeat LP and send for viral cultures and other specialized tests (PCR) depending on clinical situation
  • tx is supportive
29
Q

What is encephalitis?

Causes?

A
  • inflammation of brain parenchyma, manifested by neuro dysfxn
  • true incidence of encephalitis is difficult to determine b/c the clinical syndromes and results of routine lab tests are typically nonspecific
  • causes:
    viral
    post infectious
    autoimmune
    paraneoplastic
    med induced
30
Q

Clinical presentation of encephalitis?

A
  • alt mental status (hall mark)
  • seizures common
  • focal neuro abnorm can occur
  • exaggerated DTRs and/or pathologic reflexes
  • motor or sensory deficits
  • altered behavior and personality changes
  • speech or movement disorders
  • hemiparesis, flaccid paralysis, and parasthesias
31
Q

Imaging findings in encephalitis?

A
  • CT can r/o space-occupying lesion or brain abscess
  • MRI detects demyelination and certain pattern clues to specific etiologies
  • EEG often abnormal
32
Q

Complications of encephalitis?

A
  • status epilepticus
  • cerebral edema
  • inapprop secretion of ADH
  • cardiorespiratory failure
  • DIC
  • death
33
Q

Diff b/t meningitis and encephalitis?

A
  • presence or absence of normal brain fxn is impt distinguishing feature b/t encephalitis and meningitis
  • pts with men. may be uncomfortable, lethargic, or distracted by HA, but their cerebral fxn remains norm.
  • in encephalitis: abnorm in brain fxn are expected, included alt mental status, motor or sensory deficits, alt behavior, and personality changes and speech or movement disorders
  • seizures and postictal states can be seen in meningitis and shouldnt be just assoc with encephalitis
  • sxs and signs of meningeal irritation (photophobia and nuchal rigidity) usually absent with pure encephalitis
  • distinction b/t 2 entities is frequently blurred since some pts may have both parenchymal and meningeal process - meningoencephalitis
34
Q

Etiologies of encephalitis? viral?

A
  • only found in 35% of cases
  • HSV type 1
  • arbovirus (arthropod vectored) -
  • 3 alpha viruses: Western, Easter, and Venezualan equine encephalitis
  • flaviviruses: west nile virus, st. louis encephalitis, japanese B encephalitis, dengue and yellow fever
  • buny viruses: california encephalitis
35
Q

Non-viral/post infectious etiologies?

A
  • lyme disease
  • RMSF
  • rabies encephalitis
  • syphilis
  • TB
  • hx depending on travel, activity, area, time of year can give clues to etiologies
36
Q

Viral encephalitis findings from LP tap?

A

CSF:

  • may have increased WBCs with diff showing mostly lymphocytes
  • elevated protein, but less than 150 mg/dL
  • normal glucose
37
Q

Dx of viral encephalitis?

A
  • knowledge of pts immune status is critical
  • dx: after all other tests a brain bx can be done as last resort, but in majority of cases of aseptic meningitis and encephalitis the cause isn’t determined
38
Q

Signs and sxs of West nile virus caused encephalitis?

A
  • fever
  • malaise
  • stiff neck
  • sore throat
  • N/V
  • stupor leads to convulsions leads to coma
  • signs of UMNL (exaggerated DTRs, absent superficial reflexes, pathologic reflexes, spastic paralysis)
  • CSF protein and opening pressure increased and there will be lymphocytic leukocytosis
  • approx 1/150 infections will result in severe neuro disease
  • most sig RF is advanced age
    tx is supportive and RIBAVARIN - helpful
39
Q

RMSF encephalitis? Sxs and signs

CSF? other test?

A
  • rickettsia rickettsii: gram - intracellular bacteria
    endothelial cells: small vessel vasculitis
  • Southeast, summer
  • 2nd most common tick borne illness:
    Fever, HA, N, rash: 80%
    rash: blanching maculopapular, palms and soles, spreads centrally, later petechial and purpuric
  • hyponatremia, thrombocytopenia
  • CSF: increased lymphocytes/PMNs, increased protein, and neg gram stain
  • mild increase in LFTs
40
Q

Dx of RMSF encephalitis?

Tx?

A
  • clinical suspicion
  • low threshold to empirically tx
  • rash may be absent in 20%
  • RMSF serologies: initial may be negative, need convalescent titers several weeks later
41
Q

Tx of RMSF?

A
  • doxycycline 100 BID x 7 days
  • don’t delay!
  • no indication for proph. tx after uncomplicated tick bite
42
Q

Big pts of RMSF? Where is it? Sxs? lab values?

A
  • empiric tx if even suspected
  • in NC - any fever, HA, neuro syndrome will need tx
  • first serology titers not reliable
  • hyponatremia, low platelets, elevated LFTs, think RMSF
  • Don’t wait for the rash
43
Q

Lyme disease?

stages?

A
  • Borrelia burgdorferi
  • deer tick (smaller)
  • NE/great lakes, but reported in almost all states
  • most common cause of tick borne disease
  • stages:
    1. erythema migrans rash, viral like syndrome
    2. multiple EM lesions and/or neuro and/or cardiac findings
    3. late/chronic: intermittent or persistent arthritis and possibly subtle encephalopathy or polyneuropathy
44
Q

Tx of early and late lyme disease?

A
  • early:
    doxy 18-21 days
    amoxicillin 21-28 days
    cefuroxime 21 days

-late or severe:
cefotaxime (claforan) q 8 hrs
PCN G q 4 hrs

45
Q

Brain abscess?

A
  • focal pyogenic infection, ringed by granulation tissue and outer fibrous capsule surrounded by edematous brain tissue
46
Q

Hematogenous spread leading to brain abscess?

A
  • chronic pulm infections, lung abscess or empyema
  • skin infections
  • pelvic infections
  • intraabdominal infections
  • esophageal dilation and endoscopic sclerosis of esophageal varices
  • bacterial endocarditis (brain abscess complicates 2-4% of cases)
  • cyanotic congenital heart disease (most common in children)
47
Q

Contiguous spread - leading to brain abscess?

other origins of brain abscess?

A
  • (middle ear, sinus, teeth):
    otogenic (strep, bacteroides)- temporal lobe/cerebellum
  • sinogenic and odontogenic (anaerobic and microaerophilic streptococci) - frontol lobe
  • trauma: can develop years after the injury
  • post neurosurgical procedures: may also be delayed, more difficult to tx
48
Q

Classic triad of brain abscess?

A
  • HA, fever, focal deficit (less than 1/3 of cases)
  • toxic appearance rare
  • seizures, vomiting, confusion, obtundation possible
  • frontal lobe - hemiparesis
  • temporal lobe-homonymous superior quadrant visual field deficit or aphasia
  • cerebellum - lim incoordination or nystagmus
49
Q

Dx of brain abscess?

A
  • CT with contrast or MRI
  • LP CI!!!
  • needle guided bx or aspiration for confirmation or to direct tx in cases not responding
  • tx:
  • otogenic: cefotaxime
  • sino or odontogenic: Pen + flagyl
  • penetrating trauma or neurosurgery: Nafcillin + ceftazidime
  • hematogenous: Pen + flagyl
  • no obvious source: cefotaxime + flagyl
50
Q

Every pt with suspected meningitis should have what done unless CI?

A
  • LP

- screening CT scan if worried about IICP but isn’t necessary in majority of pts

51
Q

Usual CSF findings in pts with BM?

A
  • elevated WBCs, elevated protein and low glucose

- absence of one or more ot typical findings is of little value

52
Q

Advantage of gram stain in susp. BM?

A
  • advantage of suggesting the bacterial etiology one day or more b/f cultures are available
53
Q

Pt with encephalitis will most likely deny what sxs?

A
  • CP
  • sore throat
  • fever
  • abdominal pain
  • N/V/D
  • rash
  • can be either primary or post infectious, but typically viral
  • get a good hx!!

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