Putting holes in your head.... (fwd)

[Yoav Bergner]

I'm very confused about the mechanics of this surgery. The cranium is 
not, of course, a completely sealed-off recepticle as blood does travel 
to the brain via the carotid/jugular highway.  What is drilling the skull 
meant to do exactly?  Is the source of blood supposed to be the ruptured 
skin or membranes or what, and how is this circulation supposed to be 
kept up?  Also, as far as I remember, blood vessels bursting in the brain 
and subsequently filling it with blood is known as a stroke--which is 
rarely associated with an enlightened feeling. 

But I readily admit that my knowledge of biology is very poor, so I'd 
appreciate anyone straightening this out for me before I go out and buy a 
drill.

yb.

bergner at fas.harvard.edu