Brain death occurs when a person in an intensive care unit no longer has any activity in their brain stem, even though a ventilator is keeping their heart beating and oxygen circulating through their blood.
Once a brain stem death has occurred, the person is confirmed dead.
The brain stem
The brain stem is the lower part of the brain that is connected to the spinal cord (a column of nervous tissue located in the spinal column). The brain stem is responsible for regulating most of the automatic functions of the body that are essential for life. These are:
- breathing
- heartbeat
- blood pressure
- swallowing
The brain stem also relays all information to and from the brain to the rest of the body, so it plays a vital role in the body's core functions, such as consciousness, awareness and movement.
Persistent vegetative state
There is a difference between brain stem death and a persistent vegetative state (PVS), which can occur after extensive damage to the brain. Someone in a PVS is conscious but has no awareness of their surroundings and is incapable of feeling mental distress or physical pain. However, unlike a person with brain death, there is a slim chance that a person with PVS can recover because the core functions of the brain stem are often unaffected.
See the Health A-Z topic about Vegetative state for more information on this condition.
Outlook
Unfortunately, there is no chance of a person recovering once their brain stem has died. This is because all of the core functions of the body have stopped working and can never be restarted. Although a ventilator can keep the heart beating, the person is effectively dead.
If permission has been given, organs can be removed for transplant and ventilation is withdrawn. Once ventilation is withdrawn, the heart stops beating within a few minutes.
