One-fifth of ‘vegetative’ patients show awereness with new device

Researchers from The University of Western Ontario have discovered a practical and cost-effective method for assessing whether some patients who appear to be vegetative, may actually be conscious, but simply unable to respond. Their findings were described today in The Lancet, the world’s leading general medical journal.

Despite rigorous clinical assessment, a significant proportion of vegetative state patients are misdiagnosed. Recent studies led by Adrian Owen, a Canada Excellence Research Chair (CERC)in Cognitive Neuroscience and Imaging at Western’s Centre for Brain and Mind (CBM), have proved that a significant minority of these patients are consciously aware and, in some cases, can communicate with the outside world using functional magnetic resonance imaging (fMRI).

But while this solution is revolutionary in terms of patient care and facilitation, expense and accessibility preclude the use of fMRI assessment in the majority of vegetative patients.

“Our new method uses electroencephalography (EEG) which is relatively cheap, portable and widely available,” says Damian Cruse, the lead writer on the new study. “This means that we can now go out into the community and visit patients in their residential care homes or hospitals and provide a more accurate diagnosis than was previously possible.”

The new research shows that 19% of a group of patients who were entirely unresponsive and presumed to be vegetative, were actually aware – a figure that exceeds previous estimates of the incidence of ‘covert’ awareness in this group.


“It’s astonishing,” says Owen. “In some of these cases, patients who seemed to be entirely unresponsive to the outside world, were able to signal that they were, in fact, conscious by changing their patterns of brain activity – sometimes hundreds of times.”

Owen and Cruse collaborated with colleagues from the Medical Research Council Cognition and Brain Sciences Unit in Cambridge, the Department of Clinical Neurosciences, University of Cambridge, and the Coma Science Group, University Hospital of Liège on this study.


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