This is an excess of brain water. It often develops around an intrinsic lesion within the brain tissue e g. a tumour or an abscess, or in relation to trauma or ischaemic brain damage.
Cerebral oedema may complicate a variety of conditions, for example:
- acute hepatic failure
- benign intracranial hypertension
- Reye's syndrome
- excess fluid infusion in a dehydrated/hypernatraemic patient
- rarely in diabetic ketoacidosis
High altitude cerebral oedema may result from an abrupt increase in cerebral blood flow at 3500 - 4000 m upwards.
Different forms of cerebral oedema are described:
- caused by excessive protein rich fluid leakage into the extracellular space through damaged capillaries
- particularly affects the white matter
- treated with systemic corticosteroids
- damage is intracellular, within the neurones and glia
- CSF leaks into the extracellular space e.g. non-communicating hydrocephalus
Cerebral oedema appears as a hypodense area on CT scans.