Meningitis

Meningitis

1. INVESTIGATIONS

   • FBC
     • white cell count reflects infection can't do lumbar puncture if thrombocytopaenic
   • blood glucose & blood gas - acidosis
   • coag screen
     • cant do lumbar puncture if coagulopathy
   • CRP
   • U&E, LFTs
   • cultures
     • blood, throat swab, urine, stool for bacteria & viruses
   • Rapid antigen test
     • for meningitis organisms, can be done on blood, CSF, or urine. without LP, bacteriological diagnosis can be achieved in at least 50% of cases from the blood by culture or PCR or RAT
   • LP
     • for CSF unless contraindicated. presence of inflammatory cells in CSF confirms diagnosis
     • contraindications
       • procedure carries a risk of coning of the cerebellum through the foramen magnum - in these circumstances, can be postponed until child's condition has stabilised
       • cardiorespiratory instability
       • focal neuro signs
       • raised ICP signs
         • coma, high BP, low HR, papilloedema
       • coagulopathy
       • thrombocytopenia
       • local infection at LP site
       • delays abx
     • findings
       • Normal: clear appearance, 0-5/mm3 WBC. 0.15 -0.4g/L protein. >50% of blood is glucose. Bacterial: turbid appearance, greatly increased polymorphs, greatly increased protein, greatly decreased glucose Viral: Clear appearance, increased lymphocytes, normal or slightly increased protein, normal or slightly decreased glucose TB: turbid/clear/viscous appearance, increased lymphocytes, hugely increased protein, hugely decreased glucose.  encephalitis: clear appearance, normal or slightly increased lymphocytes, normal or slightly increased protein, normal or slightly decreased glucose
   • PCR
     • blood & CSF for possible organisms
   • serology
     • serum for comparison of convalescent titres. serological diagnosis can be made on convalescent serum 4-6 weeks after the presenting illness if necessary.
   • TB
     • CXR, Mantoux test. gastric washings or sputum, early morning urines
   • CT/MRI/EEG
     • consider if immunocompromised, CNS disease, new onset seizure, papilloedema, impaired consciousness & focal neurological signs
   • full septic workup < 3mths
     • FBC, urinalysis/culture, throat swab, blood culture, CXR, lumbar puncture

2. inflammation of meninges

3. CAUSES

   • Bacterial
     • 0-3mths
       • GBS
       • E.coli
         • &amp; other coliform bacteria
       • Listeria monocytogenes
     • 1mth - 6yrs
       • neisseria meningitidis
       • strep. pneumoniae
       • h.influenzae
     • >6yrs
   • Viral
     • EBV
       • Epstein-Barr Virus
     • adenovirus
     • enterovirus
     • mumps
       • mumps meningitis now rare due to MMR vaccine
   • Malignancy
   • Auto-immune

4. PATHOLOGY

   • bacterial infxn of meninges usually follows bacteraemia
     • damage from host response not from the infecting organism
       • inflammatory mediators
       • activated leucocytes
         • results in
           • cerebral oedema
           • decreased cerebral blood flow
           • raised ICP
       • endothelial damage
       • vasculopathy below meninges
         • cerebral cortical infarction
           • fibrin deposits
             • block resorption of CSF by arachnoid villid
               • hydrocephalus

5. HISTORY

   • fever
   • headache
   • photophobia
   • lethargy
   • poor feeding/vomiting
   • irritability
   • hypotonia
   • drowsiness
   • LOC
   • seizures

6. EXAM

   • fever
   • purpuric rash
   • neck stiffness
     • not always present in infants
   • bulging fontanelle
     • infants
   • opisthotonus
     • arching of back
   • Brudzinski/Kernig signs
     • Brudzinski - flexion of the neck with the child supine causes flexion of the knees and hips Kernig - with the child lying supine and with the hips and knees flexed, there is back pain on extension of the knee
   • signs of shock
     • tachycardia, tachypnoea, prolonged cap refill, hypotension.
   • focal neuro signs
   • altered consciousness
   • papilloedema
     • rare
   • ENT

7. COMPLICATIONS

   • hearing loss
     • inflammatory damage to cochlear hair cells may lead to deafness. all children who have had meningitis should have an audiological assessment promptly - may benefit from hearing amplification or cochlear implant.
   • local vasculitis
     • may lead to cranial nerve palsies or other focal lesions
   • local cerebral infarction
     • may result in focal or multifocal seizures, which may subsequently lead to epilepsy
   • subdural effusion
     • particularly assoc. w h.influenzae &amp; pneumococcal meningitis. confirmed by CT scan. most resolve spontaneously - may require prolonged antibiotic treatment.
   • hydrocephalus
     • may result from impaired resorption of CSF (communicating hydrocephalus) or blockage of the ventricular outlets by fibrin (non-communicating hydrocephalus). ventricular shunt may be required.
   • cerebral abscess
     • clinical condition deteriorates, emergence of signs of a space-occupying lesion. temperature continues to fluctuate. confirmed on CT scan. drainage of abscess required

8. MANAGEMENT

   • ABC
   • ABX
     • length of course of abx depends on causative organism and clinical response
     • Ceftriaxone
       • immediately if spreading petechiae, purpuric rash, signs of meningitis/septicaemia, appears ill and abnormal CRP/WBC or if in doubt.
     • ampicillin/ cefotaxime/gentamicin infants <3mths
     • IM BEN PEN
       • any febrile child with a purpuric rash should be given intramuscular benzylpenicillin immediately and transferred urgently to hospital
   • fluids
   • dexamethasone
     • beyond neonatal period, dexamethasone administered with abx reduced risk of long-term complications such as deafness

9. PREVENTION

   • vaccination: hiB, MenC, pneumococcal
   • contacts
     • meningococcal
       • rifampicin BD, ceftriaxone, ciprofloxacin
     • HIB
       • rifampicin OD x 4 days
       • Rifampicin OD X 4days