[carlr]

A myriad of doctors, most of whom have indicated that much of her brain tissue has deteriorated and possibly even liquified inside her skull.

Much is made of this point particularly as it relates to pain sensation.
I remember either reading or seeing on TV a few years ago about a person that due to illness or accident had a large portion of their brain liquefy.The doctors were amazed that in spite of this they were living almost a normal life as other undamaged portions of the brain had assumed the activities normally carried out by the damaged part.
I am not suggesting that Terri can recover but only that we cannot be sure as to what sensation she may be experiencing or how cognizant she may be yet unable to express.

[yatros from flatwater]

Just to provide grist for the discussion mill, I'd recommend: Is the Brain Really Necessary?

[AmishDude]

It's so very simple. If she's experiencing no pain, then there's no harm to her by keeping her alive. If she is experiencing pain, then starving her is nothing short of torture.