Meningitis and Encephalitis



Meningitis and Encephalitis


Suzan Schneeweiss



Introduction



  • Important and serious infection of childhood


  • Marked decline in incidence of bacterial meningitis since introduction of Haemophilus influenzae b vaccine


  • Clinical presentation of meningitis or encephalitis often nonspecific


Bacterial Meningitis



  • Neisseria meningitidis and Streptococcus pneumoniae continue to be important pathogens


  • Increasing concerns with penicillin-resistant S. pneumoniae:



    • Varies according to region (up to 20% in some regions)


    • May have cross resistance to cephalosporins; add vancomycin therapy if suspect S. pneumoniae


    • Higher doses of third-generation cephalosporin and vancomycin synergistic against penicillin-resistant S. pneumoniae


Clinical Presentation



  • Often nonspecific: fever, poor feeding, lethargy, irritability, and vomiting


  • Clinical signs: bulging fontanelle, apnea, seizures, purpuric rash


  • Older children more classic symptoms: headache, neck stiffness, photophobia


  • Kernig and Brudzinksi signs lack sensitivity


Investigations



  • CBC and differential


  • Electrolytes, urea, creatinine, blood glucose, INR, PTT



  • Blood culture:



    • Positive in 40-50% meningococcal disease, 80-90% pneumococcal and H. influenzae meningitis if no prior antibiotics


    • Neonatal meningitis: blood cultures positive in only 50%


CSF Examination


Newborn



  • > 30 × 106/L WBC, with > 60% polymorphonuclear cells


  • CSF protein > 1.7 g/L


  • CSF/ blood glucose ratio < 0.5-0.6


  • Presence of microorganisms on Gram stain


  • Latex agglutination for group B Streptococcus

    Note: Coliforms found in CSF 2-3 days after antibiotic treatment; however, group B streptococcus clears from CSF within 8 hours of treatment


Infants and Children



  • WBC: 10 × 106/L in very young infants; > 5 × 106/L older infants and children, mainly polymorphonuclear cells (generally WBC > 500 × 106/L)


  • CSF protein > 0.6 g/L


  • CSF glucose/blood glucose ratio < 0.4 obtained simultaneously


  • Cellular and biochemical changes remain in CSF fluid for 44-68 hrs after start of antibiotic treatment


  • CSF culture may be negative 2 hours post parenteral antibiotics with meningococcal meningitis and 6 hours post antibiotics with pneumococcal meningitis


  • PCR for N. meningitidis and S. pneumoniae


CT head



  • Limited use


  • Obtain if uncertain diagnosis and to rule out other causes (e.g., posterior fossa tumor)



  • Rule out complications of meningitis (e.g., cerebral abscess)


  • Decision to perform CT scan should not delay use of antibiotics


Contraindications to Lumbar Puncture

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Jun 22, 2016 | Posted by in EMERGENCY MEDICINE | Comments Off on Meningitis and Encephalitis

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