Last revised by Yahya Baba on 15 Feb 2022

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.

  • 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.

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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 meningitis
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  • Case 3: tuberculous meningitis
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  • Case 4: fungal
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  • Case 5: bacterial
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