Covert consciousness: what's in a name?

Over the past decade, it has become apparent that up to 25% of behaviourally unresponsive patients with acute or chronic disorders of consciousness reveal high spatio-temporal complexity following a direct electrical or magnetic pulse to the brain, highly differentiated EEG responses or voluntary modulation of their brain activity on command, each of which has been interpreted, to varying degrees, as evidence of consciousness. Practitioners designate this phenomenon using a dizzying variety of terms. The realization that 'unresponsiveness' does not equate to 'unconsciousness' changes how patients should be assessed and how the medical team communicates with them, their families and the world at large. We propose that the term 'covert consciousness' be used in all such communications to designate this subcategory of behaviourally unresponsive patients, with context-appropriate qualifiers and counselling accompanying its use.