Meningitis Diagnosis and Management

3 November, 2011 by: colinparker

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The word strikes fear into the heart of parents. You dare not mention the ‘M’ word unless you back it up with action, or a whole heap of calming reassurance…

The clinical features of meningitis are less straightforward in younger children, and CSF findings can be tricky to interpret. In this episode, our local Paediatric Infectious Diseases expert guides us through the topic with some clinical perspectives and insights.


Meningitis PEMcast: Outline

[cp]: intro / disclaimer

[cp]: clarification – meningitis (definition) vs meningococcal disease [MCD] (spectrum of meningitis, meningococcaemia, or both)

[all]: MCD prognosis depending on this spectrum, why?

[cp]: clarification meningitis vs encephalitis / meningo-encephalitis

Aetiology:

[cp]: – Non-infectious (‘aseptic’=non-bacterial): autoimmune, neoplastic, drug-induced

- Infectious

[RR]: viral – frequent offenders (Entero= Coxsackie/Echo, HSV less common)

[sf]: bacterial – frequent offenders

neonatal: maternal (Listeria,  Group B Strep) vs acquired source (E coli, Gram-negatives, eg Klebsiella, Staph aureus)

beyond neonatal period: Strep pneumoniae, Neisseria meningitidis, Haemophilus influenzae type B

[CB]: less common pathogens – mycobacterium tuberculosis, measles, mumps, fungal, cryptococcal in immunocompromised kids

Clinical features:

[RR]: History (headache, neck stiffness, photophobia, fever – or hypothermia in neonates)

[sf]: Examination findings (fever, meningeal irritation, rarely Brudzinski or Kernig signs, altered mental state, focal neurology, seizures, drowsiness, irritability)

[cp]: differential diagnoses (including alternate causes of fever, altered mental state, headache, neck stiffness) esp Viral illness / influenza, tonsillitis, infant sepsis (eg UTI), non-specific infant unwellness (metabolic, cardiac, intussusception)

Absence of meningism is not reassuring in the younger child!

Investigations:

[RR]: bedside – blood sugar, urinalysis (differentials), ECG maybe

[sf]: lab – utility of FBC, U&E, CRP, ESR?
[cp]: lab – role for procalcitonin?

[CB]: lab – blood cultures – how often do we get the bacterium on blood culture?

[CB]: Timing of LP (do the LP as soon as it’s safe to do it)

[RR]: imaging – need for CT prior to LP? (compare adults vs children)

[sf]: Lumbar Puncture: cautions / contraindications (raised ICP, focal seizure, seizure without full recovery, cardiovascular or respiratory compromise)
Lower threshold for LP if recent oral antibiotics, esp if febrile convulsion

Needle depth (CHW): 1.5 mm/kg (for under 10kg), 1mm/kg (10-40kg)

CSF findings:

[cp]: – normal (age-related)

neutrophils ‘lymphocytes’

(non-neutrophils)

protein glucose

(CSF:blood ratio)

neonate 0 < 20 < 1.0 >= 0.6
over 1 month age 0 < 5 < 0.4 >= 0.6

[sf]: – typical viral picture (not useful in acute stage – treat as bacterial)

[RR]: – typical bacterial picture

[CB]: – oddballs: fungal, TB, Mumps

Management:

[cp]: Steroids? Best given “before” antibiotics – role to be discussed in next episode

[RR]: Presumed or confirmed bacterial: IV antibiotics
- antibiotic choice – local guidelines, neonates different (amoxycillin for Listeria, gentamicin, cefotaxime – avoid ceftriaxone – biliary sludging)
- antibiotic duration (?stop at 48 hrs when all cultures negative, vs several weeks for some organisms)
- waters muddied by prior oral antibiotic treatment

[sf]: Presumed or likely Viral:
- usually will get antibiotics initially
- supportive care (caution with IV fluids)
- when to give antiviral agent? (HSV, VZV?)
- acyclovir dosing – body surface area vs simple weight-based 10mg/kg

[CB]: Exotic bugs (immunocompromised / travel / cranial or spinal neurosurgery) – get Microbiology / Infectious Diseases specialist advice!

[all]: last words, goodbye

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