The vegetative state: guidance on diagnosis and management.

1.3 A patient in the vegetative state (VS) appears at times to be wakeful, with cycles of eye closure and eye opening resembling those of sleep and waking. However, close observation reveals no sign of awareness or of a ‘functioning mind’: specifically, there is no evidence that the patient can perceive the environment or his/her own body, communicate with others, or form intentions. As a rule, the patient can breathe spontaneously and has a stable circulation. The state may be a transient stage in the recovery from coma or it may persist until death. The vegetative state can follow a variety of severe insults to the brain, most commonly traumatic or hypoxic-ischaemic brain injuries.