Detecting Consciousness

"Will you wake from a vegetative state? New test could tell":

A new application of a common clinical test, the positron emission tomography (PET) scan, seems to be able to differentiate between minimally conscious brains and those in a vegetative state...

After the PET scans were complete, the researchers calculated how much glucose was being consumed by the most active hemisphere of the patients’ brains relative to the healthy controls. Patients in a state of unresponsive wakefulness had 38% as much metabolic activity as the controls, minimally conscious patients showed 58% as much activity, and people being roused back to consciousness (either from sleep or anesthesia), had 63% of the normal metabolic activity.

The decision to “pull the plug” and remove a loved one from life support is never simple, but the choice could easier if we understood which patients might wake up in time. Although it’s often hard for doctors and family to pinpoint important nuances that separate a lighter state of unconsciousness from a deeper one, the PET scan might help us fill in the gaps.

The PET scan data could correctly distinguish between minimal consciousness and severe unresponsive wakefulness with 89% accuracy, the team reports today in Current Biology...