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
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-
elderly
Streptococcus pneumoniae
Listeria monocytogenes
Neisseria meningitidis
Gram negative bacilli
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adults
Streptococcus pneumoniae
Neisseria meningitidis
Group B streptococcus
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children
Neisseria meningitidis
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infants
Streptococcus pneumoniae
Neisseria meningitidis
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neonates
Group B streptococcus
Escherichia coli
Listeria monocytogenes
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-
Enterovirus
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mycobacterial meningitis
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Mycobacterium tuberculosis
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-
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
rheumatoid arthritis 2
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granulomatous
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iatrogenic
postoperative 4
hydrogel-coated aneurysm coils 3
Radiographic features
CT
may be normal
subtle hydrocephalus
hyperdensity around basal cisterns (especially in tuberculosis)
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
The complications of meningitis can be remembered using the mnemonic HACTIVE.
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