| Brain death: Prolonged cessation of all brain activity with complete absence of voluntary movements; no spontaneous breathing; no response to pain, noise, and other stimuli. Brain waves have ceased; the electroencephalogram is flat; the person is dead. |
| Locked-in syndrome: The person cannot move, except for the eyes, but normal brain waves are still apparent; the person is not dead. |
| Coma: A state of deep unconsciousness from which the person cannot be aroused. Some people awaken spontaneously from a coma; others enter a vegetative state; the person is not yet dead. |
| Vegetative state: A state of deep unconsciousness in which all cognitive functions are absent, although eyes may open, sounds may be emitted, and breathing may continue; the person is not yet dead. The vegetative state can be transient, persistent, or permanent. No one has ever recovered after two years; most who recover (about 15 percent) improve within three weeks (Preston & Kelly, 2006). After sufficient time has elapsed, the person may, effectively, be dead, although exactly how many days that requires is not yet determined (Wijdicks et al., 2010). |