Some patients in a vegetative or minimally conscious state have brain activation reflecting some awareness and cognition according to a study published in The New England Journal of Medicine.

The followed 54 patients with disorders of consciousness at two major referral centers in Cambridge, United Kingdom, and Liege, Belgium.• There were 23 people in a vegetative state (people cannot move on command or follow an object with their eyes).• The remaining 31 people in the study were diagnosed as minimally conscious (show occasional small signs of awareness).

People were given a type of brain scan called functional MRI. During the scan they were asked to think about two very different scenes. Each scene would light up a different area of the brain on the scan. Then they were asked questions. They were told to think about one scene if the answer was "yes" and the other to indicate "no." The study included only people who had brain injuries. It did not include people who had damage from lack of oxygen.

Study findings• Of the 54 patients enrolled in the study, 5 (16%) were able to answer "yes" (willfully modulate their brain activity).• Four of them were in the vegetative state group.o In 3 of these patients, additional bedside testing revealed some sign of awareness, but in the other two patients, no voluntary behavior could be detected by means of clinical assessment.o 1 patient was able to use our technique to answer yes or no to questions during functional MRI; however, it remained impossible to establish any form of communication at the bedside.

Researchers recommend that careful clinical examination could possibly result in reclassification of the state of consciousness in some of these patients. In addition, this technique may be useful in establishing basic communication with patients who appear to be unresponsive.

The differential diagnosis of disorders of consciousness is challenging. The rate of misdiagnosis is approximately 40%, and new methods are required to complement bedside testing, particularly if the patient's capacity to show behavioral signs of awareness is diminished.