personality changes after the accident

hi i have already posted a thread regarding my mothers accident.
now its been four months since her accident and she is recognising everybody and going to her daily works but ,she had lot of personality changes.
now she is talking much and more excited about anything,and lot of anger,her talking style also changed alot.
if any of ilites or your relatives have passed thru such stages please reply me .i am really worried whther we can see her as before or this is permannat with her.
its a brain stem injury doctors said.
please reply me if anybody have any information
thanq