Why does the brain enlarge in cerebral oedema?

[sameeralord]

Hi everyone,

I know it sounds obvious. But in cerbral oedema let's say due to vasgenic cause,the problem is cerebral vessels becoming more permeable and leaking out blood to extravascular compartment. Now how does the brain get bigger due to this. I mean for brain to get bigger, the intracellular fluid volume of brain cells must increase. So when these capillaries leak blood out, do near by brain cells absorb these water, increasing their intracellular volume and as a result we get enlarged brain? or does this leaked out fluid get stuck in brain interstitium making it bigger. I hope u understand my confusion, because leaking out fluid must make brain smaller otherwise. Thanks

 

[berkeman]

It doesn't actually get bigger, does it? The skull defines the volume of the brain, it would seem. The cerebral edema increases the ICP, though. Bad news.

http://medical-dictionary.thefreedictionary.com/Cerebral+oedema

cerebral edema

Etymology: L, cerebrum + Gk, oidema, swelling
an accumulation of fluid in the brain tissues. Causes include infection, tumor, trauma, or exposure to certain toxins. Because the skull cannot expand to accommodate the fluid pressure, brain tissues are compressed. Early symptoms are changes in level of consciousness: sluggishness, then dilatation of one or both pupils, and a gradual loss of consciousness. Cerebral edema can be fatal.

Mosby's Medical Dictionary, 8th edition. © 2009, Elsevier.

EDIT -- it can also be caused by high altitude sickness.