Canadian study showing ‘awareness’ in vegetative patients flawed, U.S. scientists say

A famous Canadian study claiming that a simple bedside test could detect awareness in patients believed locked in a vegetative state was flawed and the findings were most likely due to chance, according to a new analysis of the data.

U.S. researchers, reporting in The Lancet – the same journal that published the original study – say the widely publicized paper by brain scientists at the Western University in London, Ont., who used electroencephalogram (EEG) to detect brain activity in vegetative patients, may have raised false hopes about whether patients thought to be entirely unconscious are, in fact, aware and capable of communicating with the outside world.

Instead, the U.S. team says their second look at the data revealed only random fluctuations in brain activity, and not meaningful brain signals.

“We see the urgency and need every single day for tests that can be used to help establish awareness and consciousness in brain injured patients,” co-author Dr. Nicholas Schiff, a neurologist at New York – Presbyterian Hospital and Weill Cornell Medical Centre, said in a statement.

“However, we won’t help patients or their families by using a flawed research method and data that cannot accurately provide the information we’re all hoping to find.”

The American research team reanalyzed the data using different methodologies that takes into account muscle activity and “the kind of randomness that EEG signals manifest over time,” according to background material released with the study.

In an author’s response published in The Lancet, the Western neuroscientists said that while the new analysis suggests that two of the three “positive” vegetative patients didn’t always show awareness, corroborative data using functional MRI – a more powerful type of brain imaging – confirm that “these patients were aware during the same week in which the EEG data in question was acquired.”

When the Canadian team unveiled their cheap and portable method for testing patients presumed to be trapped in a permanent vegetative state in 2011, the findings were described as groundbreaking, even “astonishing.” The work was brought starkly back into the headlines in December, when the researchers reported they had tested Hassan Rasouli, the Toronto man at the centre of a landmark life support case.

Rasouli, 60, has been “without consciousness” since 2010, when he suffered complications from surgery to remove a brain tumor that left him with widespread brain damage, according to court documents. His doctors want to withdraw life-support and instead administer palliative care. His family is fighting to keep him in the ICU indefinitely on a ventilator, saying that he has shown signs of awareness. The Supreme Court of Canada is now deliberating the case.

When Rasouli was tested by Adrian Owen, one of the co-authors of the original study published in the Lancet, the tests reportedly showed a “very low level” of consciousness.

For their study reported in the Lancet in 2011, Owen and co-author Damian Cruse, of Western’s Centre for Brain and Mind, compared 16 patients with a diagnosis of vegetative state with 12 healthy patients, or “controls.” They used an EEG, which measures electrical signals from neurons.

Patients were given basic commands to use in response to a series of questions. They were told to imagine squeezing their right hand to answer yes, and moving their toes to answer no.

Three of 16 patients responded to the commands, according to their EEG responses, the authors reported. The findings, they said, showed their EEG method could identify “covert awareness” in seemingly vegetative patients.

But Weill Cornell Medical College researchers said they could find no evidence in the brain signals that the vegetative patients were actually responding to the commands, said Schiff, a leading authority on neurological disorders of consciousness.

“It’s not that bedside EEG, per se, can’t do this,” Schiff said in an interview. Several groups, including his own, have published on the potential use of EEG to detect awareness.

Rather, their method of determining awareness and interpreting the EEG signal was flawed and would lead to false positive results, he said.

Cruse and Owen “graciously” shared their data for the new analysis, the Cornell team noted.

Cruse and Owen were travelling Thursday. They declined to respond to questions from Postmedia News, pointing to their written response in The Lancet.