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.

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

  • 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
  • FLAIR C+ (Gd): has shown to be more sensitive and specific than T1 C+ (Gd) sequence in spotting leptomeningeal enhancement 6
  • MR angiography: arterial narrowing or occlusion

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

Infections of the central nervous system

Article information

rID: 4988
Synonyms or Alternate Spellings:
  • Meningitis

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Cases and figures

  • Figure 1: pneumococcal meningitis
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  • Case 1: viral (FLAIR C+)
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  • Case 2: bacterial
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  • Case 3: tuberculous meningitis
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  • Case 4: fungal
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