Experts said the findings, if replicated, would change standards in treating such patients.
Scientists have seen meaningful, responsive brain activity in such patients before, using a high-tech magnetic resonance imaging scanner. But the new study, posted online Wednesday by the journal The Lancet, is the first to demonstrate that clear signs of conscious awareness can be detected on an electroencephalogram machine by using an innovative strategy. The EEG is a portable, widely available unit that picks up electrical brain activity through electrodes positioned on a person’s head. Clinics and homes treating people with severe brain injuries are far more likely to have access to an EEG than to an M.R.I. scanner.
The research team, led by Damian Cruse and Adrian M. Owen of the University of Western Ontario, gave simple instructions to 16 people said to be “vegetative”: each time you hear a beep, imagine squeezing your right hand into a fist. The subjects were given this task and another — hear a beep, wiggle your toes — and ran through up to 200 repetitions.
In healthy people who executed these instructions, the EEG picked up a clear pattern in the premotor cortex, the area of the brain that plans and prepares movements; the electrical flare associated with the hand was distinct from that associated with the toes. The brains of three of the supposedly vegetative people showed precisely that.
“That’s about 20 percent of the patient group, producing responses that were identical to healthy volunteers,” said Dr. Owen, whose co-authors included neuroscientists from the Medical Research Council, at the University of Cambridge, and the University Hospital of Liège, in Belgium. “I think it’s a strong sign of our inability to correctly diagnose people in the vegetative state.”
...an EEG may reveal something thus far well hidden — the subjective experience of being buried alive, in a way, by a misdiagnosis. It could, the study’s authors conclude, “enable routine, two-way communication with some of these patients, allowing them to share information about their inner world, experiences, and needs.”