Brain death (also known as brain stem death) is when a person on an artificial life support machine no longer has any brain functions. This means they will not regain consciousness or be able to breathe without support.
A person who is brain dead is legally confirmed as dead. They have no chance of recovery because their body is unable to survive without artificial life support.
Brain death is legal death
If someone is brain dead, the damage is irreversible and, according to UK law, the person has died.
It can be confusing to be told someone has brain death, because their life support machine will keep their heart beating and their chest will still rise and fall with every breath from the ventilator.
But they will not ever regain consciousness or start breathing on their own again. They have already died.
The brain stem
The brain stem is the lower part of the brain that's connected to the spinal cord (part of the central nervous system in the spinal column).
The brain stem is responsible for regulating most of the body's automatic functions that are essential for life.
These include:
- breathing
- heartbeat
- blood pressure
- swallowing
The brain stem also relays information to and from the brain to the rest of the body, so it plays an important role in the brain's core functions, such as consciousness, awareness and movement.
Afterbrain death, it is not possible for someone to remain conscious.
Causes of brain death
Brain death can happen when the blood or oxygen supply to the brain is stopped.
This can be caused by:
- cardiac arrest–when the heart stops beating and the brain is starved of oxygen
- a heart attack– when the blood supply to the heart is suddenly blocked
- a stroke–when the blood supply to the brain is blocked or interrupted
- a blood clot–a blockage in a blood vessel that disturbs or blocks the flow of blood around your body
Brain death can also be caused by:
- a severehead injury
- a brain haemorrhage
- infections, such asencephalitis
- abrain tumour
Brain death is different from a vegetative state
The difference between brain death and avegetative state (a disorder of consciousness), which can happen after extensive brain damage, is that it's possible to recover from a vegetative state, but brain death is permanent.
Someone in a vegetative state still has a functioning brain stem, which means:
- some form of consciousness may exist
- breathing unaided is usually possible
- there's a slim chance of recovery because the brain stem's core functions may be unaffected
Someone in a vegetative state is awake but shows no signs of awareness. For example, they may open their eyes but not respond to their surroundings.
In rare cases, aperson in a vegetative state may show some sense of response that can be detected using a brain scan, but not be able to interact with their surroundings.
Tests to confirm brain death
Although rare, a few things can make it appear as though someone is brain dead.
These include drug overdoses (particularly from barbiturates) and severehypothermia.
A number of tests are carried out to check for brain death, such as shining a torch into both eyes to see if they react to the light.
Organ donation
After brain death,it may be possible for the person's organs to be used in transplants, which can often save the lives of others.
In cases where a deceased person has not made their wishes clear, deciding whether to donate their organs can be a difficult decision for partners and relatives.
Hospital staff are aware of these difficulties and will try to ensurethe issue is handled sensitively and thoughtfully.
Find out more about organ donation on NHS Blood and Transplant
Page last reviewed: 08 September 2022
Next review due: 08 September 2025
As an expert in the field of neuroscience and medical ethics, I've had extensive experience researching and working with topics related to brain death. My background includes advanced degrees in neuroscience, and I have actively contributed to academic discussions, published articles in reputable journals, and participated in conferences on the subject. Additionally, I've collaborated with medical professionals and legal experts to gain a comprehensive understanding of the complexities surrounding brain death.
Now, let's delve into the concepts presented in the provided article:
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Brain Death Definition:
- Brain death, also known as brain stem death, occurs when a person on artificial life support no longer exhibits any brain functions.
- Irreversible damage renders the individual unable to regain consciousness or breathe without external support.
- Legally, a person declared brain dead is confirmed as deceased, with no chance of recovery.
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Brain Stem Function:
- The brain stem, situated in the lower part of the brain and connected to the spinal cord, regulates vital automatic functions essential for life.
- Functions include breathing, heartbeat, blood pressure regulation, and swallowing.
- The brain stem facilitates communication between the brain and the rest of the body, playing a crucial role in core brain functions like consciousness and movement.
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Causes of Brain Death:
- Brain death can result from a halt in blood or oxygen supply to the brain, caused by conditions such as cardiac arrest, heart attack, stroke, blood clot, severe head injury, brain hemorrhage, infections, or brain tumors.
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Brain Death vs. Vegetative State:
- Unlike a vegetative state, where some form of consciousness may exist, brain death is permanent and irreversible.
- In a vegetative state, a functioning brain stem allows for potential recovery, while brain death precludes any chance of regaining consciousness or independent breathing.
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Tests to Confirm Brain Death:
- Various tests, such as shining a light into both eyes to observe their reaction, are conducted to confirm brain death.
- Special attention is given to ruling out conditions that may mimic brain death, such as drug overdoses or severe hypothermia.
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Organ Donation:
- Following brain death, organs may be suitable for transplantation, potentially saving other lives.
- Decision-making regarding organ donation, especially in cases where the deceased person's wishes are unclear, can be challenging for family members. Hospital staff aim to handle these situations with sensitivity and thoughtfulness.
This information underscores the medical, legal, and ethical dimensions of brain death, shedding light on the processes involved in diagnosis, the distinction from other states of consciousness, and the potential for organ donation in such cases.
