"A population of patients exists who meet all the behavioural criteria for the vegetative state, but nevertheless retain a level of covert awareness that cannot be detected by thorough behavioural assessment," said the report in The Lancet, a British medical journal.
The study raises the likelihood that many misdiagnosed patients have been starved to death, pro-life advocates said.
A group of doctors in Europe performed electroencephalography (EEG) on 12 control subjects and 16 patients who had been diagnosed to be in a persistent vegetative state (PVS). After attaching electrodes to the patients' heads to measure brain activity, the researchers instructed the patients to imagine they were making a fist and wiggling their toes. Three of the 16 patients produced EEG responses similar to those of conscious controls.
While the patients were unable to produce physical responses, the report cited the cognitive functions that were demanded of them. Sustained attention of 90-second blocks, response selection between the two imagery tasks, language comprehension of the instructions and working memory to recall which task to do were all successfully performed by the three patients.
Functional magnetic resonance imaging (fMRI), which utilizes a magnetic field and radio frequency pulses to produce pictures of internal body organs, has been relied upon in the past for diagnosis, but researchers from this study concluded EEG is a more efficient tool for that purpose. According to the report, EEG is better suited for evaluating patients for various reasons: It is portable, cheaper than existing methods of clinical assessment and can be used with patients who have metal implants.
In response to the study, Burke Balch, director of the National Right to Life Committee's Robert Powell Center for Medical Ethics, expressed concern that the lives of many who were wrongly diagnosed as being in a vegetative state have been taken.
"Many patients, probably thousands, have had their food and fluids cut off and died, based on what we now know may well have been mistaken assumptions that they had lost all capacity for consciousness," Balch said. "The Lancet EEG study, together with earlier functional MRI studies, holds out the hope that we may develop ways to communicate with aware patients who have routinely been diagnosed as 'vegetative,' much as today eye movements and blinks are used to communicate with some patients with paraplegia. That would certainly be a positive alternative to starving them to death."
The starvation death of Terri Schiavo in 2005 is probably the most noteworthy battle to date over the fate of a person diagnosed as being in a vegetative state. Schiavo, 41, who had suffered brain damage, passed away two weeks after the removal of her feeding tube. Schiavo's husband won a legal fight with her pro-life parents and siblings to cut off food and liquids for his wife.
He said the study's results "only reinforce our family's contention that the PVS diagnosis needs to be eliminated -- particularly given the fact that it not only dehumanizes the cognitively disabled, but it is being used in some instances to decide whether or not a person should live or die, as it was used in Terri's case. None of us deserves to be deprived of food and water."
Holly Naylor is an intern with the Washington bureau of Baptist Press.
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