What does brain damage feel like?

Sorry for the title, it really doesn't represent what I'm looking for entirely but it was the best I could come up with.

I have a sister that has been diagnosed as locked-in by a handful of doctors and yet diagnosed as vegetative by others. She suffers brain anoxia. I have heard professional opinions that link the brain to the body and of course those that separate the mind from the body. It has led to one thing: what does brain damage feel like for the individual suffering?

I'm not looking for opinions on being vegetative or locked-in, I'm looking for first hand accounts of what it feels like "mentally" to be suffering brain damage. Is it like being under water, a sort of intoxicated type feeling, where the mind is completely intact but the individual has no control or just some control over the body? I've worked with people that claimed their mind works fine but as hard as they try they cannot manipulate their bodies to respond the way they want. I've known people who have lost their memories due to brain damage but yet could still think and process things normally.

Any information anyone can provide would be very helpful to me. My sisters brain injury was a result of anoxia.
Not sure if that makes a difference as to the type of mental experience people have.