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Leptomeningitis, which are more commonly referred to as meningitis, refers to inflammation of the subarachnoid space (i.e. arachnoid mater and pia mater). It is usually infective.


  • pyogenic meningitis
    • elderly
      • Listeria monocytogenes
      • Streptococcus pneumoniae
      • Neisseria meningitidis
      • Gram negative bacilli 
    • adults
      • Streptococcus pneumoniae
      • Neisseria meningitidis
      • Group B Strep
    • children
      • Neisseria meningitidis
    • infants
      • Streptococcus pneumoniae
      • Neisseria meningitidis
    • neonates
      • Group B Strep
      • E. coli
  • viral meningitis
    • Enterovirus
  • chronic meningitis
  • fungal meningitis
Aseptic meningitis

Radiographic features

  • may be normal
  • subtle hydrocephalus
  • hyperdensity around basal cisterns (especially in tuberculosis
  • leptomeningeal enhancement
  • complications or sources of the meningitis
  • T1: may be normal; sulci may appear less hypointense than normal
  • T1 C+ (Gd): leptomeningeal enhancement
  • FLAIR: demonstrates hyperintense signal in CSF space, especially in the sulci
  • MR angiography: arterial narrowing or occlusion


The complications of meningitis can be remembered using the mnemonic HACTIVE.

See also

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