A local priest has a huge ragged star shaped scar that covers most of the right side of his face. I asked one of his parishoners what the story was there.
When a child the priest had been shot in the back of the head by one of those south american death squads and thrown in a mass grave. He crawled out of the grave and was found in time for his life to be saved.
The star shaped scar was the remnant of the exit wound, the bullet coming out just below the right eye.
Unless theres enough hydraulic shock to turn the brain to mush, the most common cause of death from a wound to the brain or brain case is hemoraging that has no easy exit. Blood builds up in the brain case crushing the brain tissue.
Since so little of the brain's mass is actually used, much of it may be destroyed without causing death or permanent disability.
Some functions of the brain may shift to surviving otherwise unused brain cells.
A few people have survived removal of one half of their grey matter and recovered completely.
If a very important junction of ganglia is destroyed thats a different matter.