Despite such caveats, the research is "critically important," according to Dr. Michael DeGeorgia, director of the Neurocritical Care Unit at University Hospitals Case Medical Center in Cleveland.
It "illustrates both the complexities of this area and the limitations of our bedside clinical examination," he said in an e-mail, adding that more research will be needed to figure out how to use the technology and how to interpret the results.
The research "does raise difficult medical and legal questions," DeGeorgia said.
"We always need to be upfront and honest with families about what we know for certain and what we do not know for certain," he said. "In many of these cases, the honest answer is that we cannot be absolutely 100 percent certain that their loved one isn't 'in there somewhere.'"