When people have a brain injury so severe that they can't squeeze a loved one's hand or otherwise respond, there are few good ways to tell if they have any lingering awareness or are in a vegetative state. Now researchers have created a tool to peek inside the brain and measure varying levels of consciousness.The work reported Wednesday is highly experimental, not ready for bedside use yet — and if it pans out, a big question is how to use it without raising false hope. No one knows what level of consciousness at a certain point after injury really predicts recovery.
But it offers the hope that one day doctors might track consciousness nearly as easily as they check blood pressure."Consciousness can grow and shrink," said Marcello Massimini, a neurophysiologist at Italy's University of Milan who led the research to quantify just how much that is happening under different circumstances.It seems obvious — consciousness fades during deep sleep, and doctors can slip us under with anesthesia. Yet scientists don't have a good way to measure consciousness, especially when the very ill appear to be unconscious.
It's important to try to distinguish if patients are at least minimally conscious, and not in a vegetative state, because the sooner there's some sign of awareness, the better the chance of recovery.Today, doctors check if those patients can do things like blink or move a limb on'mand, or react to touch or pain. If not, scans of the brain's electrical activity may offer clues. Scientists even have put seemingly unconscious patients inside MRI scanners and told them to imagine throwing a ball. How the brain reacts can indicate if they're aware and just can't show it, what's called locked-in syndrome. But all these tests have drawbacks.