A feature I wrote back in 2007 explored how neuroscientists are using brain imaging to try to better understand—and even communicate with—people with severe brain injuries. In one startling case, Adrian Owen, a neuroscientist at the Medical Research Council in Cambridge, found that a patient thought to be in a vegetative state and who showed no outward signs of awareness could respond to yes or no questions by visualizing a specific thing; playing tennis to indicate yes or to walking through her house for no. Owen’s team read her responses via functional MRI.

The findings were astounding. As I noted in the feature; ‘While the patient met all the clinical requirements for being in a vegetative state, her fMRI clearly showed a brain capable of relatively complex stimulus-processing.’

But the looming question that remained was whether this patient was a one in a million case or whether she was indicative of a number of brain injured patients who are cognitively aware but unable to communicate.

Nicholas Schiff and collaborators at Weill Cornell Medical College have now tried to answer that question, imaging the brains of six patients with conditions ranging from minimally conscious, in which people have some awareness and can occasionally communicate, to locked-in syndrome, the result of damage to the brainstem that leaves people cognitively intact but unable to move. According to a press release from the university;

They found there was a wide, and largely unpredictable, variation in the ability of patients to respond to a simple command (such as “imagine swimming – now stop”) and then using that same command to answer simple yes/no or multiple-choice questions. This variation was apparent when compared with their ability to interact at the bedside using voice or gesture.

Some patients unable to communicate by gestures or voice were unable to do the mental tests, while others unable to communicate by gestures or voice were intermittently able to answer the researchers’ questions using mental imagery. And, intriguingly, some patients with the ability to communicate through gestures or voice were unable to do the mental tasks.

The researchers say these findings suggest that no exam yet exists that can accurately assess the higher-level functioning that may be, and certainly seems to be, occurring in a number of severely brain-injured patients – but that progress is being made.

“We have to abandon the idea that we can rely on a bedside exam in our assessment of some severe brain injuries. These results demonstrate that patients who show very limited responses at the bedside may have higher cognitive function revealed through fMRI,” says Schiff.

The research was published February 25 online in the journal Brain.