Definition and epidemiology
Acute meningitis is most commonly bacterial in origin, but it can also be viral in orign.
- Streptococcus pneumoniae
- Neisseria meningitidis
In adults, pneumococcus and meningococcus are the most common causes.
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:
|Colour||Clear fluid||Cloudy, purulent fluid||Clear fluid|
|Pressure||6 – 20 cmH2O||↑↑||↑|
|WBC||0 – 5 /µL||↑↑
|Protein||0,18 – 0,45 g/L||↑||Normal|
|Glucose||0,45 – 0,80 g/L||↓||Normal or ↓|
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.
9B. Thrombosis of the intracranial sinuses
10B. Intracerebral haemorrhage (ICH)