Table 1

Definitions of disorders of consciousness*

Coma (absent wakefulness and absent awareness)A state of unrousable unresponsiveness, lasting >6 hours in which a person:
  • cannot be awakened

  • fails to respond normally to painful stimuli, light or sound

  • lacks a normal sleep-wake cycle

  • does not initiate voluntary actions

Vegetative state (VS) (wakefulness with absent awareness)A state of wakefulness without awareness in which there is preserved capacity for spontaneous or stimulus-induced arousal—evidenced by sleep-wake cycles and a range of reflexive and spontaneous behaviours.
VS is characterised by complete absence of behavioural evidence for self-awareness or environmental awareness
Minimally conscious state (MCS) (wakefulness with minimal awareness)A state of severely altered consciousness in which minimal but clearly discernible behavioural evidence of self-awareness or environmental awareness is demonstrated22
MCS is characterised by inconsistent, but reproducible, responses above the level of spontaneous or reflexive behaviour, which indicate some degree of interaction with their surroundings
  • *Adapted with permission from the RCP PDOC guidelines.

  • PDOC, Prolonged Disorders of Consciousness; RCP, Royal College of Physicians.