Disorders of consciousness (DOC) are a group of conditions characterized by impaired verbal and motor responsiveness to diverse stimuli, indicating disturbed consciousness (Bernat, 2006). Almost uniformly, these disorders result from an acute and severe brain injury. In younger patients, this is often a head trauma caused by an accident, while in older patients the causes are more often stroke, brain hemorrhage or hypoxic brain injury due to cardiopulmonary arrest (in which the brain lacks oxygenated blood for several minutes). The acute severe brain injury immediately induces a coma, which is a state of complete unresponsiveness with eyes closed in which even the most painful stimuli cannot elicit any verbal or behavioral responses (Young, 2009). If the patient survives, the clinical situation stabilizes and the brain slowly starts to recover, the patient can transition into an unresponsive wakefulness syndrome (UWS), also called vegetative state. This is indicated by the fact that the patient resumes periods of wakefulness with eyes open, alternating with periods of sleep with eyes closed.
Racine E, Sample M. The competing identities of neuroethics: Remarks on theoretical and methodological assumptions and their practical implications for the future of neuroethics, in Karen Rommelfanger and Syd Johnson, édit., New York : Routledge Handbook of Neuroethics, Juillet 2017, Chapitre 1