Plot Thickens In Dispute Over Consciousness In Vegetative Patients

"Brain function in coma, vegetative state, and related disorders". The Lancet Neurology 3 (9): 537–546. | date 2011-11-30 | (Neurowiki via Wikimedia Commons)

“Brain function in coma, vegetative state, and related disorders”. The Lancet Neurology 3 (9): 537–546. | date 2011-11-30 | (Neurowiki via Wikimedia Commons)


In late November, we reported on some striking experiments that suggested there may be shreds of consciousness in patients who appear to be in a long-term “persistent vegetative state.”

Health columnist Judy Foreman wrote:

The recent work by [University of Western Ontario researcher Adrian] Owen, and others, using fMRI brain scanning technology shows that some patients diagnosed as being in a persistent vegetative state may actually have some degree of consciousness and be able to communicate, that is, by sheer thinking, be capable of answering comparatively simple questions such as “are you in pain?”

Owen’s work found signs of consciousness in a seemingly vegetative patient, Scott Routley:

Essentially, Owen trained Routley to answer questions through a kind of game. When he asked Routley to imagine himself playing tennis, a particular part of his brain, the premotor cortex, lit up on the fMRI brain scans “with a very big signal.” (The premotor cortex sends signals to the motor cortex, which actually signals muscles to move.) Routley learned that imagining to play tennis, thus lighting up this part of his brain, meant “yes.”

Now, the plot thickens: New York-based researchers are calling some of Owen’s findings into question — not those MRI scans, but “bedside” brain-wave checks using EEG readings. The Neuroskeptic blog reports on the back-and-forth here beneath the pithy headline “Another Scuffle In The Coma Ward.” It posts an example of the brain-wave data in dispute and explains:

This image shows that in a healthy control, EEG activity was “clean” and generally normal. However in the coma patient, the data’s a mess. It’s dominated by large slow delta waves – in healthy people, you only see those during deep sleep – and there’s also a lot of muscle artefacts which can be seen as ‘thickening’ of the lines.

These don’t come from the brain at all, they’re just muscle twitches. Crucially, the location and power of these twitches varied over time (as muscle spikes often do).

This wouldn’t necessarily be a problem, the critics say, except that the statistics used by Owen et al didn’t control for slow variations over time i.e. of correlations between consecutive trials (non-independence). If you do take account of these, there’s no statistically significant evidence that you can distinguish the EEG associated with ‘hand’ vs ‘toe’ in any patients.

From the challengers’ Jan. 24 press release:

A team of researchers led by Weill Cornell Medical College is calling into question the published statistics, methods and findings of a highly publicized research study that claimed bedside electroencephalography (EEG) identified evidence of awareness in three patients diagnosed to be in a vegetative state.

The new reanalysis study led by Weill Cornell neurologists Drs. Andrew Goldfine, Jonathan Victor, and Nicholas Schiff, published in the Jan. 26 issue of the journal Lancet, reports the statistical results and methodology used by a research team led by University of Western Ontario scientists and published online Nov. 9, 2011, also in the Lancet, was flawed in a number of crucial ways. Due to these errors, the reanalysis concludes it is impossible to determine whether or not these vegetative state study subjects demonstrated any degree of awareness during the testing.

The University of Western Ontario researchers in the original study set out to use bedside EEG technology to identify any changes in brain activity in vegetative patients and also healthy subjects as controls. During the study, each subject was asked to either imagine moving their hand or foot each time they heard an electronic beep. The brain activity following hand or foot commands was recorded using EEG and then compared in the study. The published study claimed that three of the 16 tested vegetative patients successfully performed the task, along with 9 of the 12 healthy controls. The reanalysis of this study is important, the Weill Cornell researchers say, because if the method was indeed valid, it would mark an important breakthrough in the field — the first evidence using a bedside testing method that patients reported to be in a vegetative state could perform high-level cognitive tasks.

“Sadly, our reanalysis of the research team’s original data shows these particular methods do not work, and it is important that scientists, physicians, and most importantly, the families of severely brain injured patients understand that the conclusions reached in the original study were most likely due to chance findings,” says the corresponding author of the reanalysis, Dr. Schiff, the Jerold B. Katz Professor of Neurology and Neuroscience, professor of neuroscience in the Feil Family Brain and Mind Research Institute and professor of public health at Weill Cornell.

“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. However we won’t help patients or their families by using a flawed research method and data that cannot accurately provide the information we are all hoping to find,” says Dr. Schiff, who is also a neurologist at NewYork-Presbyterian Hospital/Weill Cornell Medical Center.

My personal reaction, after seeing many patients in persistent vegetative states when I visited my late mother, who was also in that condition: I always thought the less consciousness these poor patients had, the better.

Not only were they completely unable to respond in any way to the world around them, they also frequently seemed to be in discomfort, their limbs contracting and their breathing labored, despite the best of care. This is surely a scientific dispute that will take some sorting out, but if in fact Owen’s findings were in error, that may actually be a good thing for patients and comforting to their families.

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