leptomeningitis

Postcontrast
Fluid-attenuated inversion recovery (FLAIR) MRI of a case of meningitis. It shows the enhancement of meninges at the tentorium and in the parietal region, with evidence of dilated ventricles.
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Leptomeningitis, which is more commonly referred to as meningitis, represents inflammation of the subarachnoid space (i.e. arachnoid mater and pia mater) caused by an infectious or noninfectious process.

Pathology

Etiology
Infective
  • pyogenic meningitis
    • elderly
      • Streptococcus pneumoniae
      • Listeria monocytogenes
      • Neisseria meningitidis
      • Gram negative bacilli
    • adults
      • Streptococcus pneumoniae
      • Neisseria meningitidis
      • Group B streptococcus
    • children
      • Neisseria meningitidis
    • infants
      • Streptococcus pneumoniae
      • Neisseria meningitidis
    • neonates
      • Group B streptococcus
      • Escherichia coli
      • Listeria monocytogenes
  • viral meningitis
    • Enterovirus
    • JC virus meningitis
  • mycobacterial meningitis
  • fungal meningitis

For a further discussion related to other etiological agents and other infective processes in the CNS, please refer to CNS infectious diseases.

Aseptic meningitis

Radiographic features

CT
  • may be normal
  • subtle hydrocephalus
  • hyperdensity around basal cisterns (especially in tuberculosis) 
  • leptomeningeal enhancement
  • complications or sources of the meningitis
MRI
  • 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
  • FLAIR C+ (Gd): has shown to be more sensitive and specific than T1 C+ (Gd) sequence in spotting leptomeningeal enhancement
  • MR angiography: arterial narrowing or occlusion

Treatment and prognosis

Complications

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

See also

Siehe auch:
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