People who are mentaly handicapped and even in comas are conscious unlike people in a PVS.
There was some dispute about that -- she may have been minimally conscious. But the PET scan which could show what whatever was left of her brain was doing in response to external stimuli, was systematically denied by Michael.
She got done to death with the connivance of the law. No ifs, ands, and buts about it.
No, people in comas are not, by definition, "conscious."
It's not surprising that you are confused by the use of "PVS" as a standard. The British Medical Journal reported that 43% of those with the diagnosis of PVS are misdiagnosed.
http://bmj.bmjjournals.com/cgi/content/abstract/313/7048/13
(even full content is free to the public in this Journal)
Be sure and take a look at those articles that have reference this article and which have been published more recently.
People in comas are not conscious.