It seems as if barely a year goes by without a painful, public and often politicized controversy over whether or not someone is in a “vegetative state,” beyond consciousness and some say the need for life support. The most famous case was that of Terri Schiavo in 1990.
Part of the reason for these disputes is that bedside clinical tests that provide answers to such profound questions of responsiveness are to a large extent a matter of medical guesswork.
Indeed, according to important new research, those tests have a decent chance of being wrong.
People said to be in a vegetative state in a small but significant number of cases probably aren’t.
Moreover, there’s a way to get it right, according to the research, by using the brain scan technology called positron emission tomography (PET).
The research is published in the current edition of the medical journal The Lancet. Summaries for lay readers are available here and here. The research was done by a team of 15 scientists, led by Steven Laureys from the University of Liége in Belgium.
It used two types of scanning technology, PET and magnetic resonance imaging (MRI), to test 126 patients with severe brain injury referred to the University Hospital of Liége. The researchers then compared their results with an established behavioral test of whether someone is capable of regaining consciousness.
They found, first, that the PET scan was more accurate than the MRI.
More importantly, according to the Lancet study, the PET scan revealed that a third of the 36 patients diagnosed as “behaviorally unresponsive” using the standard hospital test “showed brain activity consistent with the presence of some consciousness.”
And nine patients in this group subsequently recovered a “reasonable level of consciousness,” the Lancet article said.
“Our findings suggest that PET imaging can reveal cognitive processes that aren’t visible through traditional bedside tests, and could substantially complement standard behavioral assessments to identify unresponsive or ‘vegetative’ patients who have the potential for long-term recovery,” Laureys said in a statement.
The vegetative state is also known as unresponsive wakefulness syndrome. It is a “condition of complete unawareness of the self and the environment,” says the New England Journal of Medicine.
“Patients in a vegetative state show no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli; show no evidence of language comprehension or expression.”
What the research shows, Laureys said in an interview with the Washington Post, is that sometimes “there’s more going on than we thought” in the brain.
“We can’t make ethical or medical or legal decisions which are right if we we’re not having good diagnoses,” he said. “We need to reduce” the interpretive element as much as possible.
While the researchers acknowledge that PET scanning isn’t generally available or practical in most hospital situations, their study is likely to speed the day when it is, perhaps making heated controversies over vegetative states easier to resolve. Laureys said that expensive as the technology may be, it’s less costly than keeping someone who is in a coma alive for months and even years on the chance of revival.
On the one hand, Laureys said, a scan that shows no brain responsiveness may make families more comfortable about stopping various forms of life support. And if a scan shows consciousness, a patient might be aroused to the point of participating in the decision about life support.
On the other hand, if life support and feeding are to be withheld, “we better get it right.”
He said this doesn’t mean a patient deemed conscious should be kept alive for a long time using heroic means. “That is often a quality of life” decision, he said. “Too often it’s politically polarized. Pro. Con. The right to life. The right to die. In reality, it’s more nuanced.”
It is the first time that researchers have tested the diagnostic accuracy of these brain-imaging techniques in clinical practice.
Scientists Jamie Sleigh and Catherine Warnaby called the study “encouraging” in an article in “The Conversation.”
In patients with substantial swelling of the brain, working out whether they might wake up is usually done through clinical examination – testing whether they respond to stimuli such as light shone in the eyes – and structural brain imaging. But in many cases the accuracy of predicting the outcome is no better than flipping a coin….
The exciting part of the new study is that we might be starting to make some progress in understanding the parts of the brain that are necessary for the conscious state, and we can use this to look into the brains of problematic patients to see if these critical regions of the brain are functioning – even if there are no outward signs.
Michael Bloomfield of the Medical Research Council Clinical Sciences Centre in London told Britain’s The Courier:
This really exciting study suggests for the first time that a brain scanning technique called PET could be used in the future to predict the likelihood that a patient may “wake-up” a long time after a severe brain injury. However, much more research is needed to work out how accurate PET scans might be at doing this and make the technique reliable enough to be potentially used in specialist centres.
If the results of this study are confirmed in future research, this could have far-reaching clinical, ethical and legal implications, including whether to offer an apparently unconscious patient pain relief and, ultimately, whether treatments that may be keeping someone alive should be continued or not.