I'm no neurologist, but there is a known medical condition where people are incapable of recognizing pain. Very rare, there are only a handful in the US, but they do exist. It involves a failure from the back of the brain (which knows how to recognize pain) to the front, (which says "oh, damn, this hurts"). The persons with this disorder can recieve horrible injuries, without what we call "pain", because their front isn't getting the message. She doesn't HAVE a front of the brain, for all intents, so it's the same result.
To go with a metaphor. Let's say I'm the back of the brain, sitting there switchboarding and keeping everything going. I get the nerve responce saying "hey, this ain't cool". I send the "get away" message back, then tell the concious part of the mind that the body is displeased (which is pain). However, there's no one on at the other end of the line.
So, the question is almost like the metaphysical "tree falling in the woods". Biologically, yes, the signals are being sent. But they never make it to their destination. Pull out her brain and replace it with a healthy one, and that new inhabitant would be quite upset. But, for her, it feels no different than any other day for the last 15 years.
