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II. Cerebral Edema

Edema may occur in a number of diseases, and may lead to increased intracranial pressure. Following an infarct, edema peaks between two and four days after the ischemic event and may exert a mass effect; intravenous mannitol may be helpful in therapy. 

A. Vasogenic Cerebral Edema (most common form of edema) - Increased permeability of small vessels (breakdown of blood‑brain barrier)

Vasogenic cerebral edema iinvolves the escape of fluids and proteins from the vascular system into the extracellular space. Because the fluid can flow along fiber tracts, the swelling may be greater in white matter than in gray matter.

B. Cytotoxic Cerebral Edema (cellular brain edema) - Increased permeability of cell membranes secondary to cellular injury

Cytotoxic cerebral edema involves the intracellular accumulation of excess fluid, usually due to disruption of ion pumps in the cell membrane. It is common in ischemia or in other conditions such as metabolic poisons. Because neurons are most vulnerable to cell injury, cytotoxic edema may be more severe in gray matter than white matter.

C. Hydrocephalic (Interstitial) Edema - Fluid flows from CSF into brain through ventricular lining in cases of hydrocephalus