10A. Acute meningitis

Page created on June 3, 2021. Not updated since.

Definition and epidemiology

Acute meningitis is most commonly bacterial in origin, but it can also be viral in orign.


  • Bacteria
    • Streptococcus pneumoniae
    • Neisseria meningitidis
  • Virus
  • Non-infectious

In adults, pneumococcus and meningococcus are the most common causes.

Clinical features

The patient usually has general signs of infection in addition to meningeal signs, like neck stiffness and photophobia. They may also have altered mental status.

In case of meningococcal meningitis, the patient may develop petechial rash.

Diagnosis and evaluation

Lumbar puncture and CSF analysis is essential. The findings depend on the etiology:

Normal Bacterial Viral
Colour Clear fluid Cloudy, purulent fluid Clear fluid
Pressure 6 – 20 cmH2O ↑↑
WBC 0 – 5 /µL ↑↑

Mostly granulocytes

Mostly lymphocytes

Protein 0,18 – 0,45 g/L Normal
Glucose 0,45 – 0,80 g/L Normal or ↓
Culture Negative Positive Negative

In cases where LP could cause tonsillar herniation, like in increased ICP, a head CT should be performed before the LP. CT/MRI can also be used to rule out focal lesions like abscess or cerebral venous thrombosis.


Bacterial meningitis patients should be isolated and treated with antibiotics as soon as the lumbar puncture is taken. Dexamethasone improves the outcome in pneumococcal or meningococcal meningitis, so it should be given if they are suspected causes.

For viral meningitis, the treatment is supportive.

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9B. Thrombosis of the intracranial sinuses

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10B. Intracerebral haemorrhage (ICH)

Parent page:
Neurology 2

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