Neurology >
Meningitis

“An infection of the protective membranes that surround the brain and the spinal cord (the meninges)”

Risk Factors
  • Extremes of age (<5 or >60)
  • Those with a suppressed immune system (e.g. HIV, on immunosuppressants)
  • Chronic kidney failure
  • Diabetes Mellitus
Aetiology
  • Infective
    • Bacterial – e.g. Neisseria meningitides
    • Viral – e.g. Mumps, enteroviruses
    • Fungal – e.g. Cryptococcus neoformans)
  • Non-infective (e.g. malignant meningitis)
Pathophysiology
  • Microorganisms reach the meninges either by direct (e.g. ears, cranial injury) or bloodstream spread.
    • Acute bacterial: pia-arachnoid congested with polymorphs, resulting in pus formation and adhesions
    • Chronic infection: brain covered in exudate with meningeal tubercles
    • Viral: lymphocytic inflammatory CSF reaction without pus formation, polymorphs or adhesions
  • NB cerebral oedema occurs in all bacterial meningitis infections
Clinical Presentation
  • Early: headache, leg pains, cold hands and feet, abnormal skin colour
  • Later: Meningism (neck stiffness, photophobia, positive Kernig’s sign), decrease in GCS, seizures, petechial rash
  • NB: in acute bacterial symptoms more intense and develop within minutes/hours, whereas many viral meningitides have less prominent signs
Investigations
  • Bloods:
    • FBC, U+Es, LFT, glucose, coagulation screen
    • Blood cultures
    • Serology
  • Imaging:
    • Chest X-Ray – looking for TB signs
    • CT Chest
  • Special:
    • Throat swabs, and rectal swab
    • Lumbar puncture: if bacterial appears turbin, polymorphs predominant cell, high cell count/mm3, glucose <1/2 plasma, >1.5g/L protein)
Management
  • Minutes save lives and local policies vary
  • <55yrs: cefotaxime 2g/6hr slow IV
  • >55yrs: cefotaxime + ampicillin (to cover Listeria)
  • Viral: Aciclovir
Complications
  • Cranial nerve lesions (leading to e.g. hearing loss, blindness)
  • Paralysis
  • Ataxia
  • Recurrent seizures
  • Problems with memory and concentration

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