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.
On this page:
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
- elderly
-
viral meningitis
- Enterovirus
- JC virus meningitis
- mycobacterial meningitis
- Mycobacterium tuberculosis
- fungal meningitis
- Cryptococcus neoformans (in patients with AIDS)
- Coccidioides immitis
For a further discussion related to other etiological agents and other infective processes in the CNS, please refer to CNS infectious diseases.
Aseptic meningitis
- leptomeningeal carcinomatosis
- rheumatoid arthritis 2
- granulomatous
- iatrogenic
- postoperative 4
- hydrogel-coated aneurysm coils 3
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 6
- MR angiography: arterial narrowing or occlusion
Treatment and prognosis
Complications
- hydrocephalus
- subdural empyema
- epidural empyema
- cerebritis and cerebral abscess
- infarction
- ventriculitis
- dural sinus thrombosis
The complications of meningitis can be remembered using the mnemonic HACTIVE.
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