meningitis

see also:

• the child with headache
• headache
• causes of, and risk factors for meningitis
• cerebrospinal fluid (CSF)
• meningococcal septicaemia
• meningococcal chemoprophylaxis
• RCH guideline - meningitis
• RCH guidline - acute meningococcal disease
• RCH guideline - headache
• NSW NETS - bacterial meningitis (pdf)
• AFTB lectures - meningitis
• AFTB lectures - meningococcaemia
• Meningitis Mx wall chart (pdf)

• bacterial meningitis and meningococcal sepsis are two separate but overlapping entities which often co-exist
• most cases of bacterial meningitis result from seeding from an episode of bacteraemia with a virulent organism (although in neonates, this may just be from an organism causing a UTI)
• some cases of bacterial meningitis result from extension of regional infection, such as from V-P shunts, etc.

• high priority triage (eg. triage 2)
• A,B,C's as usual
• iv access
• check BSL
• bloods for FBE, U&E, blood cultures x2 sets, clotting profile, meningococcal PCR
• careful iv fluid resuscitation if hypotense as high risk of delayed APO - see sepsis / septicaemia
• stratify risk (see below) to decide who gets immediate antibiotic Rx, and who gets CT/LP
• if primarily septicaemic, immediate iv antibiotics DO NOT do LP
• if primarily meningitis, consider LP before iv antibiotics if not contraindicated (see below) and doesn't delay antibiotics by more than 20-30min.
• iv dexamethasone 0.15mg/kg to max 10mg qid for 4 days start before or at 1st dose antibiotics, particularly for pneumonococcal cases. Cease if non-bacterial cause identified.
  • reduces mortality, severe hearing loss and long-term neurological sequelae in bacterial cases, esp. if pneumococcal.
• iv ceftriaxone 50mg/kg to max 2g bd
• consider iv benzyl penicillin 60mg/kg to max 2.4g 4hrly or ampicillin 2g qid if immunosuppressed or possible Listeria (eg. age < 3 months or age > 55 years)
• consider adding vancomycin 12.5 mg/kg up to 500 mg IV 6-hrly if Strep. pneumoniae or Staph. aureus are suspected, or neutrophils are in CSF but no organisms seen (and if viral meningitis / meningococcal disease are unlikely).
• patients with altered mental state should be considered for possible herpetic meningoencephalitis and consideration given to empirical iv antiviral Rx as well such as iv aciclovir and related antivirals (famciclovir, valaciclovir)
• infectious disease isolation measures
• nurse patient at 30deg head up if altered mental state
• if meningococcal disease, it is a notifiable disease and will need contact tracing and chemoprophylaxis for contacts.

• presence of meningococcal rash
• fever, headache, photophobia and objective neck stiffness (not just soreness)
• fever with seizures (excluding typical febrile convulsions in young children)
• fever with altered mental state (excluding post-ictal following a typical febrile convulsion or other obvious cause for the mental state change)
• sick looking febrile neonate or infant
• rectal temp > 38deg C in a neonate (aged < 1 month or weighing < 3.5kg)¹⁾
• NB. at risk patients with known spinal abnormalities such as spina bifida or V-P shunts should have early neurosurgical consults

• febrile neonate or infant
• fever, headache, with photophobia &/or neck soreness with no other focus of infection evident
• fever, headache and already on antibiotics

• see also interpretation of CSF findings
• most patients require the diagnosis to be confirmed by lumbar puncture (LP) as confirmation will not only aid diagnosis but assist in determining duration and type of ongoing antibiotic Rx.
• patients with atypical presentations in whom tuberculosis (TB) is possible, should be considered for 10ml CSF sent for TB cultures in addition to usual CSF studies.
• unless the risk of an intracranial mass lesion (eg. abscess, subdural empyema) is very low (eg. previously well young adult or child with illness < 24hrs), a CT brain is usually recommended prior to performing a lumbar puncture (LP).

• shock
• widespread rash
• evidence of coagulopathy
• drowsiness / impaired consciousness
• signs of raised ICP (bradycardia, hypertension, papilloedema, periodic breathing)
• focal neurology
• mass lesion on CT scan
• possible hydrocephalus on CT scan
• if LP is contraindicated due to possible raised intracranial pressure, neurosurgical consultation may be indicated to consider a diagnostic ventricular tap.

• meningitis is one of the main dilemmas for the ED physician
• missing or delaying Rx for a case may have fatal consequences
• the gold standard for diagnosis involves CT brain and lumbar puncture (LP) - both of which are resource-intense, costly and expose the patient to significant risks
• for every 1 case of meningitis, there may be 1,000 cases of fever and headache - you can't be doing an LP on them all!
  • 95% of adult patients with meningitis have at least 2 of fever, headache, neck stiffness and altered mental state - but this does not help us because nearly all influenza patients will have fever and headache.
  • altered mental state is generally a late symptom and is present in about half the patients at presentation, but this means absence of altered mental state is not in itself reassuring.
  • neck stiffness is NOT a reliable sign in young children or the immunocompromised
• a blood test does not allow the exclusion or the diagnosis of meningitis (excluding PCR but these are not immediately available to alter ED Mx)
• patients who are already on antibiotics can become a diagnostic nightmare for the ED physician as clinical signs and even CSF findings become less reliable to exclude meningitis.
  • prior antibiotics usually prevent the culture of bacteria from the CSF.
  • antibiotics are unlikely to significantly affect the CSF cell count or biochemistry in samples taken <24 hours after antibiotics.
• thus one needs to stratify risk to decide who gets immediate antibiotic Rx, and who gets CT/LP, and who can be observed, and who can be safely discharged.
• furthermore, an LP cannot fully exclude bacterial meningitis on micro findings alone, and thus if one has a high clinical suspicion of bacterial meningitis, the safe option is to treat with appropriate iv antibiotics +/- aciclovir and related antivirals (famciclovir, valaciclovir) EARLY and continue them irrespective of CSF micro results.

• no fever or meningism signs but just lethargy, obtundation

• may have subtle signs

• poor feeding, irritability, vomiting
• “a sick looking child with a fever has meningitis until proven otherwise”

• this makes diagnosis tough!
• this is more likely to be the case with patients already on oral antibiotics
• see cerebrospinal fluid (CSF)

• BestBets.org - use of steroids in children with meningococcal shock seems reasonable