Deciding whether a gravely injured person is actually in a vegetative state or just unable to respond has long been a challenge.
But scientists have found it may be possible to make a more confident diagnosis with a new method that has already found signs of conscious awareness in three patients thought to be brain-dead.
Even more surprisingly, the scientists have done so with a brain scanner that is more common and low-tech than the machines that had previously been used to try to detect consciousness.
The "new" brain scanner is an electroencephalogram (EEG), which, ironically is an older, less expensive machine than the kind of brain scanner that has been used to look for consciousness in vegetative patients: a(fMRI).
For the 25,000 Americans with serious brain injuries who are thought to be in a vegetative state, this breakthrough could help prevent some of them from suffering, as the New York Times puts it, "the subjective experience of being buried alive, in a way, by a misdiagnosis."
How the experiment worked
The research team, led by Damian Cruse and Adrian M. Owen of the University of Western Ontario, hooked 16 people in a vegetative state up to an EEG, a common medical device that measures electrical activity in the brain through electrodes placed on a person’s head.
The scientists then asked them to imagine that they were making a fist with their right hand whenever they heard a beep. In another exercise, they had them imagine that they were wiggling their toes when they heard a beep.
The scientists compared their EEG results to those of healthy people who were asked to imagine the same thing.
Three of the supposedly brain-dead people showed the same two brain patterns (one for the hand, one for the toes) that the healthy study subjects displayed during the experiments: Activity for both showed up in the premotor cortex, the region of the brain that sets physical movements in motion.
The subjects who displayed the brain activity of conscious people made up 20% of the study group. They were men (aged 29, 35 and 45) who had been pronounced vegetative for the past three months to two years.
The researchers, from the University of Western Ontario, Cambridge University and University and University Hospital of Liège, Belgium, published their results Wednesday in the medical journal, The Lancet.
Reducing the number of misdiagnoses
EEGs could improve the diagnoses for brain damaged individuals, especially because standard methods of determining conscious awareness are known to lead to misdiagnoses.
Current techniques look for whether someone's eyeballs can track moving objects or whether someone can follow commands or answer questions with finger twitches or blinks. But such tests can lead to misdiagnoses for people who are intermittently conscious.
As reported in the New York Times Times, Dr. Owen said of the results, “I think [the results are] a strong sign of our inability to correctly diagnose people in the vegetative state.”