Published November 10, 2011
Scientists have used a portable device that tracks changes in brain waves to communicate with people in a vegetative state, some of whom have been locked in their bodies for more than a year.
In a study published last year in the New England Journal of Medicine, researchers showed it was possible to communicate with and detect awareness in people in a vegetative state using functional magnetic resonance imaging or fMRI.
The team then tried far less expensive, portable equipment to get a better idea of how many people classified as being in a vegetative state are actually aware of their surroundings.
The researchers instructed 16 people in a vegetative state to imagine they were making a fist with their right hand or wiggling their toes, and then measured brain activity while electrodes were attached to their scalp.
"It was possible to detect that these patients were actually aware" despite being diagnosed as being "entirely unconscious" using standard clinical assessments, said Professor Adrian Owen of the Center for Brain and Mind at the University of Western Ontario. Findings from the newer study were published in the British journal Lancet on Wednesday.
Patients in a persistent vegetative state have periods of wakefulness, but they are completely unresponsive and are thought to be unaware.
"We don't actually know how many vegetative patients there are. It's now possible to find that out," said Dr. Damian Cruse of the University of Western Ontario, who led the study.
Using an MRI machine requires moving patients from nursing home facilities to academic medical centers for the costly scans, and some have metal implants, ruling out use of magnetic-based scanners.
Cruse devised a way to assess patients using a portable electroencephalography (EEG) device, which is used to record electrical activity in the brain. The devices also cost far less, from $25,000 to $90,000, compared with some $3 million for an MRI machine.
They compared the patients' brain responses to those of 12 healthy volunteers.
Three of the 16 people in a vegetative state were able to reliably activate the same parts of their brain that become active when healthy individuals are given the same command.
Owen said the three patients ranged in age from 20 to 45 years and had different types of injuries.
"One of the patients had been in a vegetative state for almost two years and yet he was able to understand what we were trying to do and show he was aware," despite looking completely vegetative, Owen told a news briefing.
Curiously, three of the 12 healthy volunteers were not able to reliably activate areas in the brain used when making a fist or wiggling toes, even though they were very much aware of their surroundings.
Cruse said patients in a vegetative state may have been much more motivated to do the task because they were eager to show that they were aware of their surroundings.
Owen said the findings are preliminary, but they show it is possible to use less expensive equipment to reassess patients in a vegetative state who may have been misdiagnosed.
In the future, the researchers envision using the devices to help people communicate with the outside world, giving doctors important information about their state of mind and whether or not they are in pain.
"All of the technological and scientific building blocks are already in place. We know we can develop brain computer interfaces to move cursors and even spell out words," Owen said.