I cannot imagine being trapped within only the confines of my thoughts and no way to tell the outside world I am in pain or any other discomfort.
Yikes!
True, but on the other hand, you might be having a great dream and not have to worry about getting woken up in the middle of it.
Yikes!
And there are legal means to prevent that from happening. I filled out an exhaustive questionnaire provided by my attorney which asked for those medical conditions under which I refuse to continue to live and demand that all life-support (including food and water) be withheld.
My wife, who holds my medical power of attorney can, if necessary, go to a court and demand that my wishes be honored, i.e. if the doctors refuse to comply.
As I said, there are means.