News

Researchers challenge findings of team that showed awareness in three patients in vegetative state

BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f719 (Published 01 February 2013) Cite this as: BMJ 2013;346:f719
  1. Clare Dyer
  1. 1BMJ

Questions have been raised about the findings of a study that hit the headlines two years ago claiming that electroencephalography had shown awareness in three patients who were in a vegetative state.

The 2011 study was carried out by the postdoctoral fellow Damian Cruse, the British neuroscientist Adrian Owen, and colleagues at the University of Western Ontario’s Centre for Brain and Mind in London, Ontario, in collaboration with Cambridge University and the University of Liège. It used electroencephalography to look at the brain images of 16 patients, thought to be in a vegetative state, after they were asked to undertake two tasks: making a fist and wriggling their toes.1

Owen, a neuroscientist who previously worked at Cambridge, moved in 2011 with his research team to the Canadian university, where he took up the Canada excellence research chair in cognitive neuroscience and imaging.

His team provided its data to researchers from Weill Cornell Medical College in New York, who have now claimed in a letter to the Lancet, which published the original study, that the methods of Owen’s team were flawed.2

The Weill Cornell researchers, who include the neurologists Nicholas Schiff and Andrew Goldfine, argued that a proper analysis of the data showed that it was impossible to say whether the three patients showed any awareness.

They did not take issue, however, with the findings of other research by Owen and his team that used functional magnetic resonance imaging (fMRI) to detect signs of consciousness.

Their letter was published in the Lancet on 26 January, along with a response from Owen and colleagues, who defended their methods and stood by their conclusions.2 3 Owen’s team pointed out that independent fMRI testing that showed areas of brain activation in response to task requests was available for two of the three patients.

“These data confirm that these patients were aware during the same week in which the EEG data in question was acquired,” they write in their response.

They said that they shared the Weill Cornell scientists’ goal: to find a way to determine whether patients in whom a vegetative state was diagnosed have conscious awareness despite their inability to communicate.

“Indeed, our goal, like that of Goldfine and colleagues, is to develop increasingly sensitive tools to identify covert command-following and, in that spirit, we have recently published a method that more formally addresses many of their current concerns.

“Clearly, it is only through the continuing improvement of our complementary approaches that we will converge on the optimum methods for accurately identifying covert awareness, where it exists, in every severely brain-injured patient.”

Cruse told the BMJ, “The term ‘reanalysis’ is misleading. What they actually did was analyse our data using an entirely different approach. It’s not at all surprising, then, that they came up with ‘different’ results.

“The critical point, however, is that their approach failed to detect awareness in most of the healthy controls in our original 2011 study. It is of no surprise, then, that it also failed to detect awareness in the three vegetative state patients.

“Since our original article was published we have published a study in PLoS One, in which we use a statistical approach that is not affected by many of the comments of the Cornell group, and also find reliable EEG signs of awareness in a patient who had been diagnosed as vegetative for 12 years.4 In short, EEG remains a viable bedside method for detecting covert awareness in the vegetative state. What this exchange amounts to is a series of minor scientific quibbles about how that might best be demonstrated.”

Notes

Cite this as: BMJ 2013;346:f719

References