Cerebral edema - classification, etiology, and pathogenesis.
Cerebral edema is an abnormal accumulation of fluid within the brain parenchyma, leading to increased brain volume and raised intracranial pressure.
Classification
- 1 Vasogenic edema
Most common type.
Due to breakdown of blood-brain barrier (BBB) → increased vascular permeability → fluid (mainly plasma proteins and water) leaks into extracellular space, especially white matter.
- 2 Cytotoxic edema
Due to cellular (neuronal, glial, endothelial) swelling.
Occurs when Na /K -ATPase pump fails, leading to intracellular accumulation of sodium and water.
Mainly affects gray matter and white matter.
- 3 Interstitial (hydrocephalic) edema
Due to trans-ependymal flow of CSF into periventricular white matter.
Occurs with obstructive (non-communicating) hydrocephalus.
Etiology (Causes)
Vasogenic edema
Trauma (e.g., contusions).
Tumors (e.g., metastases disrupting BBB).
Abscesses.
Inflammatory conditions (e.g., meningitis, encephalitis).
Cytotoxic edema
Hypoxic- ischemic injury (e.g., stroke, cardiac arrest).
Severe metabolic disturbances (e.g., hyponatremia, hypoglycemia ).
Certain toxins.
Interstitial edema
Obstructive hydrocephalus (e.g., tumor blocking ventricular system).
Severe CSF overproduction (rare).