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CNS Infections. 11-23-04 Chapter 235. Bacterial Meningitis. Epidemiology. 400 per 100,000 in neonates 1-2 per 100,000 in adults S pneumoniae & N meningitidis m/c HIB vaccine has been very effective Mortality 5% in children beyond infancy 25% in neonates and in adults. Pathophysiology.

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cns infections

CNS Infections

11-23-04

Chapter 235

epidemiology
Epidemiology
  • 400 per 100,000 in neonates
  • 1-2 per 100,000 in adults
  • S pneumoniae & N meningitidis m/c
    • HIB vaccine has been very effective
  • Mortality
    • 5% in children beyond infancy
    • 25% in neonates and in adults
pathophysiology
Pathophysiology
  • S. pneumonia and N. meningitidis (and H. influenzae) are encapsulated which provides them with increased ability to invade BBB
  • Upper airway bloodstream subarachnoid space subcapsular constituents trigger inflammation fever, meningimus, change in MS brain/meningeal edema decreased CSF drainage hydrocephalus increased ICP ICP>CPP
clinical features
Clinical Features
  • 25% of adult cases “classic”
    • Rapid development of
      • Fever
      • HA
      • Stiff neck
      • Photophobia
      • Change in MS
  • Nonspecific signs/symptoms in very young/old
  • 25% will develop seizures
clinical features6
Clinical Features
  • History
    • Living conditions
      • College dorm/barracksN meningitidis
    • Trauma
      • Recent neurosurgeryStaph/gram(-) rod
    • Immunocompetence
    • Immunization hx
      • NoneHiB
    • Antibiotic use
clinical feratures
Clinical Feratures
  • Physical Exam
    • Brudzinski
      • Passive neck flex hips & knees flex
    • Kernig
      • Flex hip, ext knee hamstrings contract
    • Skin
      • Purpura
      • Petechiae/splinter hem, pustular lesionsmicroemboli
    • Fundi
    • Neuro Exam
diagnosis
Diagnosis
  • Parenchymal
    • CT is the imaging of choice
      • Brain abscess, encephalitis, toxoplasmosis
  • Meningeal
    • Lumbar puncture
      • Neoplasm, CNS vasculitis, SAH
diagnosis10
Diagnosis
  • An aseptic profile
    • Must think about…
      • Partially treated bacterial infection
      • Bacterial infections adjacent to the subarachnoid space
diagnosis11
Diagnosis
  • Tests to order on the CSF
    • Tube #1 cell count with diff
    • Tube #2 protein,glucose
    • Tube #4 cell count with diff, gram stain/culture
    • Tube #3
      • Viral cultures
      • Borrelia (lyme disease)
      • India ink/cryptococcal antigen (immunocomp)
      • Acid fast stain/culture for mycobacteria (TB)
      • Latex agglutination for bacterial Antigens
      • PCR
        • Herpes, arbovirus
lumbar puncture
Lumbar Puncture
  • Contraindications
    • Infection in overlying skin
    • Relative
      • Coagulopathy
      • Thrombocytopenia
    • If delay is anticipated obtain blood cultures and GIVE antibiotics
      • You have 2 hours after ATB given before sensitivity is effected
lumbar puncture13
Lumbar Puncture
  • Considerations for not obtaining CT before performing LP
    • Age <60
    • Immunocompetent
    • No h/o CNS disease
    • No recent seizure (<1week)
    • Normal sensorium & cognitition
    • No papilledema
    • No focal neuro deficits
treatment
Treatment
  • First priority
    • Antibiotics
  • Second priority in some cases
    • Anti-inflammatories
  • Third priority
    • Counter the adverse effects of increased ICP & vasculopathy
emperic antivirals
Emperic Antivirals
  • Concern of herpes
    • Acyclovir 10mg/kg IV Q 8 hours
steroids
Steroids
  • Dexamethasone
    • 10mg IV 15 minutes prior to antibiotics
    • Shown to decrease M&M in S. pneumoniae but NOT N. meningitidis
        • N Engl J Med 2002; 347:1549-1556, Nov 14, 2002.
complications
Complications
  • Seizures
  • Hyponatremia
  • SIADH
  • CVA
  • Coagulopathies
  • Cognitive deficits, epilepsy, hydrocephalus, hearing loss affect 25% of survivors
chemoprophylaxis
Chemoprophylaxis
  • Household/school/daycare contacts last 7 days
  • Direct exposure to secretions
    • Kissing, sharing utensils/toothbrushes, mouth to mouth, intubation without a mask
  • First line: rifampin 10mg/kg (max dose 600mg) Q12h x 4 doses
  • Alternative: ceftriaxone, cipro, sulfisoxazole
viral menigitis
Viral Menigitis
  • 85% secondary to
      • Echo-
      • Coxsackie
      • Entero-
  • Also consider HSV, and EBV
  • Neutrophils may predominate in the CSF in the first 24 hours
  • Consider starting ATB’s until cultures come back (-)
viral encephalitis23
Viral Encephalitis
  • Infection of brain parenchyma
  • Presents of neurological abnormalities distinguish it from meningitis
epidemiology24
Epidemiology
  • Incidence is 1/10 of bacterial meningitis
  • HSV-1, zoster, EBV,CMV, rabies, arbo
    • Arbo
      • LAC (La Crosse)-diagnosed most frequently
      • SEE(St Louis)-20% mortality in elderly
      • WEE(Western)- causes seizures in 90% of infected infants, permanent neuro deficits in 50%
      • EEE(Eastern)- most devastating, mortality 70%
      • WNV(West Nile)
pathophysiology25
Pathophysiology
  • Portals of entry
    • Arbo-transmitted by mosquitoes, ticks
    • Rabies-bite by infected animal
  • Hematogenous dissemination v. travel backwards on axons (HSV,HZV,rabies)
  • Dysfunction & damage caused by disruption of neural cell function & inflammation
pathophysiology cont
Pathophysiology cont.
  • Gray matter predominately affected
    • Cognitive/psychiatric signs, lethargy, seizures
  • White matter affected in post-infectious encephalomyelitis
clinical features27
Clinical features
  • New psych symptoms
  • Cognitive deficit (aphasia, amnesia, confusion)
  • Seizure
  • Movement d/o
diagnosis28
Diagnosis
  • MRI-more sensitive than CT
  • CT
  • EEG
  • LP-findings consistent with aseptic meningitis
differential
Differential
  • Exclude the killers
    • Bacterial meningitis & SAH
  • More meningeal symptoms
    • Lyme, TB, fungal, bacterial, viral, neoplastic
  • More parenchymal symptoms
    • Abscess, bacterial endocarditis, post-infectious encephalomyelitis, toxic or metabolic encephalopathy
treatment30
Treatment
  • HSV: acyclovir 10mg/kg IV
  • CMV: ganciclovir
  • Rabies/EEE/HSVdevastating & usually fatal or residual deficits
brain abscess32
Brain Abscess
  • Focal pyogenic infection
  • Pus-filled cavity ringed by granulation tissue & outer fibrous capsule surrounded by edematous brain tissue
epidemiology33
Epidemiology
  • Paranasal sinus focus
    • 10-30 y/o
  • Otic
    • Bimodal: <20 y/o & >40 y/o
pathophysiology34
Pathophysiology
  • Hematogenous spread
    • 1/3 of cases
  • Contiguous (middle ear, sinus, teeth)
    • 1/3 of cases
    • Otogenic (Bacteroides)temporal lobe/cerebellum
    • Sinogenic & odontogenic(anaerobic & microaerophilic streptococci)frontal lobe
clinical features35
Clinical Features
  • Classic triad
    • HA, fever, focal deficit
      • <1/3 of cases
    • Toxic appearance is rare
    • Seizures, vomiting, confusion, obtundation possible
    • Frontal lobe-hemiparesis
    • Temporal lobe- homonymous superior quadrant visual field deficit or aphasia
    • Cerebellum-limb incoordination or nystagmus
diagnosis36
Diagnosis
  • CT with contrast
  • LP contraindicated
  • Biopsy or aspiration for confirmation
questions
Questions
  • 1. CSF analysis returns with the following values: glucose 20 WBC 1200 Protein 300. This profile is consistent with
    • A. Bacterial meningitis
    • B. viral meningitis
    • C. Fungal meningitis
  • 2. Which of the following is an absolute contraindication to performing an LP
    • A. Coagulopathy
    • B. Infection of the overlying skin
    • C. thrombocytopenia
questions39
Questions
  • 3. T/F Steroids have been shown to decrease morbidity & mortality in meningitis caused by Strep pneumo
  • 4. T/F Brain abscesses are confirmed by LP.
  • 5. Which antibiotic regimen should be initiated in an immunocompromised patient suspected of having bacterial meningitis without any allergies
    • A. Pen G
    • B. Ceftriaxone & vanco
    • C. Vanco, gent, & ceftazidime
  • Answers: 1. A 2. B 3. T 4. F 5. C