Also used for
seasonal depression,
clinical depression,
chronic fatigue syndrome,
concussions,
tumors,
headaches,
insanity. Personal, non-medical reasons say that increased
blood, and therefore
oxygen, in the
brain allows it to work better (enlightenment).
The goal is to reveal the meninges, but not to cut it, as that would let the fluid that protects the brain go all over.
When drilling through the skull, one may hit a couple bone vessels. Also, when peeling back the scalp on top of the head, the person performing the operation should remember that the scalp is attached to the skull with some tissue, and the scalp should be marked for major veins, and remember that head wounds bleed a lot. The drilling is amplified by the skull resonating.
The brain does pulse when exposed. First hand experiences say that one can feel a bit of water (it's actually spinal fluid) actually sloshing about in the hole.
Of a couple accounts I've read, one person thinks his state of mind was not increased because of the procedure, but simply because he was paying an extreme amount of attention to the details of his changes, and that this attention did some of the things the procedure was supposed to do, and that the only effects are simply psychological, not physiological. Far from the magic some hope for.
source: Bme (www.bmezine.com} for the experiences. Interesting interview.