New research using a portable electrode test suggests nearly 20 percent of those previously determined to be vegetative state may be consciously aware of their surroundings and even able to communicate through easily detectable brain signals.
The results, published today in Lancet, could offer some hope for many caregivers who face the complex decision to keep their loved ones in a vegetative state alive when they're awake but seemingly unaware.
"The assumption that they lack awareness is based on the assumption that there are no outward signs they are aware," said Adrian Owen, co-author of the study and Canada Excellence Research Chair in Cognitive Neuroscience and Imaging at the University of Western Ontario.
Owen and his colleagues hooked 16 patients in a vegetative state to electroencephalography (EEG) machines and asked the patients to move their right hands and their toes, and repeated the test with 12 healthy patients.
The EEG showed brain activity in front part of the brain in three of the 16 patients -- the same area that showed activity in the healthy group -- which suggested they understood and responded to those commands.
The patients who responded varied so widely in their conditions that researchers said it's difficult to know what type of person may be more likely to display signs of consciousness. One of the patients who responded to the command had been in a vegetative state for nearly two years.
The test could potentially offer those who have been unresponsive but aware for many years to express themselves, the researchers said.
Over the last five years, many studies using functional magnetic resonance imaging, fMRI, have been able to detect whether some patients are consciously aware of their environment. But vegetative patients are often hard to transport to large fMRI machines, compared to EEGs, which involve placing tiny electrodes on the patient's scalp. In some cases, an fMRI test can cost up to $3 million, according to the researchers.
The EEG machine the researchers used costs about $90,000 and the results proved as effective as their studies using fMRI, they said.
"It's been impossible to answer how many patients are out there who may really be conscious," said Owen. "There's been a limit to how many we can get around to and how many we can scan."
Owen called EEG a portable and more affordable technique that could potentially, "assess consciousness at the bedside."
"It will allow us to get out into the community and answer simple questions, like how many patients are there?" he said.
The researchers said they will work to create a "brain computer interface" -- an EEG operating computer response system to help patients who are conscious communicate more regularly.
"This opens up a whole new world of communicating with these patients to see what their world is like," said Owen. But the findings could bear weight on the ethical debate of whether results from the EEG should dictate whether a person should be kept alive.
"Most patients and families are concerned with quality of life," said Dr. Ferdinando Mirarchi, medical director in the department of emergency medicine at the University of Pennsylvania Medical Center.
While the patients were able to follow simple commands, it does not suggest that the patients would be competent to make their own decisions about their state, the researchers said.