A new tool that could help us measure awareness in comatose patients

One of the more frustrating aspects of treating patients who are in a vegetative or minimally conscious state is that we really have no idea just how conscious or unconscious they really are. As a consequence, medical practitioners are left guessing about how to best treat their patients, while family members struggle to understand how mentally engaged their loves ones might be. Thankfully, neuroscientists in Belgium are looking to change all this by developing a tool that can quantify conscious awareness.

Most patients in a minimally conscious state appear to be insensitive to their surroundings, often making jerky, reflexive movements. Appearances can be deceiving, however. What we don't know is how busy they might be on the inside.

Complicating the problem is the diversity of what's experienced by vegetative patients. In some cases, like the Terry Schiavo story from a few years back, it's very likely there is no awareness involved owing to severe cognitive impairment. But we can't always make this assumption.

Back in 2010, a study published in the New England Journal of Medicine showed that some patients in a vegetative state can respond to questions — responses that could only be measured with an fMRI. This remarkable revelation strongly indicated that we should not jump to conclusions about just how "brain dead" a person might appear to be.

And it's this exact problem that Melanie Boly, a postdoctoral fellow at Belgian National Fund for Research, is trying to correct. To that end, Boly, along with her colleagues, are working to develop a numerical measure of consciousness by pulsing the brain of vegetative patients with a brief electromagnetic wave, and then measuring any neural responses using electrodes applied to the scalp.

The early results are promising. Nature reports:

In six patients diagnosed as vegetative, the electromagnetic pulse elicited responses with complexity indices similar to those in sleeping or anaesthetized healthy subjects. Twelve minimally conscious patients showed slightly more complex responses. And two ‘locked-in' patients - people who are fully conscious but unable to move or communicate - showed complexity indices similar to healthy, awake subjects.

Once fully developed, doctors will be able to determine the cognitive complexity of the thought patterns in vegetative patients — and on a case-by-case basis.

And the implications are fairly substantial; caregivers will need to be respectful of the needs of fully or semi-conscious patients, while others who exhibit permanent and exceedingly low levels of consciousness (if any) may be officially declared as deceased.

Image: Andrea Danti/shutterstock.com.