The detection of conscious awareness in individuals who have suffered an extremely severe brain injury has implications for the provision of care, the prediction of the likelihood of recovery, and for decision-making regarding the prolongation of life.
Historically, knowing that someone is conscious has relied on the observation of a behavioural response to a verbal or nonverbal stimulus. However, recent advances in neuroimaging have enabled the identification of patterns of neural activity associated with thoughts, actions and intentions, and this promises to provide the means to detect whether a physically unresponsive brain-injured patient is aware of their environment even though they are unable to indicate this through a purposeful movement or speech.
While formal definitions of consciousness elude neuropsychologists and philosophers alike, it is generally accepted that it involves not just wakefulness but also awareness of the self and the environment. A person who is aware is necessarily awake; however, one who has suffered an injury to the brain may be awake but not aware.
The criteria of wakefulness and awareness are employed to distinguish disorders of consciousness: coma, the vegetative state, and the minimally conscious state. Following a very severe brain injury, a patient who is neither awake nor aware is determined to be in a coma. In...
