Coma and related disorders

Abstract

SummaryDisorders of consciousness represent a major challenge in clinical practice. The last decade of neuroscience research brought new insights about brain function and neural correlates of these pathological states of consciousness. Although behavioural evaluation still remains the gold standard, conscious behaviours are too often missed, leading to unwanted grey zones between conscious and unconscious patients. In order to increase the chances of detecting the signs of consciousness, scientists now focus on the development and validation of neuroimaging and electrophysiological paradigms in noncommunicative patients. Recent insights in this field also raise new questions of medical ethics. Indeed, for conscious patients, legal questions will occur about treatment plans, rehabilitation and communication strategies while for the unconscious patients, end-of-life decisions will take place after the p atients' condition is stated as "permanent" or "irreversible". Coma and related disordersFor a long time, the primary seat of consciousness was believed to be localised only in the cerebral cortex [1]. It was only very recently that scientists were confronted with a great discovery. In 1949 neuroscientists found, through a nimal intracranial electrophysiological experiments, that the activation of the brain stem reticular formation was a ssociated with the level of arousal [2]. However, like other revolutionary discoveries, the idea was then abandoned some years later following many controversies. Fortunately, due to our recent advancements in consciousness research, these subcortical correlates of consciousness were brought back. In fact, we do not argue anymore that a preserved r eticular formation system is essential for normal vigilance, while the intralaminar nuclei of the thalami are implicated in higher order brain processes since the thalamus is the first centre for the integration and filtering of sensory inputs [3,4]. These subcortical structures are working closely together