NRL News

Lancet study shows patients incorrectly diagnosed in a PVS

by | Apr 22, 2014


By Dave Andrusko

Dr. Steven Laureys, one of the co-authors of the Lancet study

Dr. Steven Laureys, one of the co-authors of the Lancet study

A study published last Tuesday in the medical journal “The Lancet” finds that “significant number of people labeled vegetative had received an incorrect diagnosis and actually had some degree of consciousness and the potential to improve,” according to Denise Grady of the New York Times.

The results of the study, lead by Dr. Steven Laureys, is consistent with the conclusions of previous research that employed electroencephalogram machines and M.R.I. scanners which “have also found signs of consciousness in supposedly vegetative patients.”

The difference with the latest study, conducted by a team of 15 scientists, is that when researchers used a three-dimensional brain imaging technique called positron emission tomography (PET), they found that even more patients were incorrectly diagnosed as in a “persistent vegetative state” [“Diagnostic precision of PET imaging and functional MRI in disorders of consciousness: a clinical validation study”].

The following is a summary of the study, some of the positive highlights, but also the reasons for concern.

  • Of the 122 patients studied, 81 were considered “minimally conscious,” defined by Grady as “meaning they showed intermittent signs of awareness and responsiveness.” The other 41 “had been declared vegetative — awake but with no behavioral signs of awareness.”
  • The team used two types of scanning technology, PET and magnetic resonance imaging (MRI). “The researchers then compared their results with an established behavioral test of whether someone is capable of regaining consciousness,” the Washington Post’s Fred Barbash reported. “They found, first, that the PET scan was more accurate than the MRI.”
  • “The [PET] imaging tests found minimal consciousness in 13 of the 41 vegetative patients,” Grady reports. “After a year, nine of the 13 had progressed into “minimally conscious states or a higher level of consciousness,” according to the researchers.

Laureys told the Washington Post 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

That’s the good news. Less promising is what might be made of this increased ability to fine-tune the diagnoses—that is, separate those who supposedly are “truly” in a PVS and those who are in a minimally conscious state. The latter “have a better chance of improving than those who are vegetative, though recovery may take a long time and be incomplete,” Grady writes.

For example, in a statement, Laureys wrote

“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.”

In his interview with the Post, Laureys elaborated. Barbash writes

“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.’”

Three quick points.

First, if there is one overriding lesson from this study, and others like it that we we’ve reported on, it’s that large numbers of patients with severe brain injuries are quickly—and often inaccurately—labeled in a PVS. A study that concludes this or that technique (in this case, a PET) gives you a finer distinction could easily be rendered obsolete within a few months or years. In the meanwhile, offering “assurances” that doctors know with certainty that a patient is in a PVS makes it even easier to pressure families into withholding food and fluids.

Second, scientists Jamie Sleigh and Catherine Warnaby are “encouraged” by the study. Writing in “The Conversation,” they note,

“[I]n 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.”

But even laymen who follow the search for an “explanation” of what is consciousness know that this could easily be a quest that never finds an answer. It is incredibly complicated and is as much art as science, as much a philosophical question as it is about interpreting “data.”

Grady’s story ends with quotes from Dr. Joseph J. Fins, the chief of the medical ethics division at Weill Cornell Medical College in New York, who was not involved in the study.

“’[PET scans] help you discriminate who’s who,’ Dr. Fins said.

“Too often, he and Dr. Laureys said, patients are labeled vegetative and sent to nursing homes where no effort is made to rehabilitate them, and where emerging consciousness might not even be recognized.

“’The first thing we owe these people is a credible diagnosis,’ Dr. Fins said.

Which leads me to the last point.

Third, you don’t starve anyone to death, regardless of their diagnosis.

Please join those who are following me on Twitter at Send your comments to

Categories: PVS
Tags: PVS