Brain Death

What is brain death?

“Brain death” is the medical and legal term for death that happens when your brain stops working. In brain death, injury or illness does severe, permanent damage to your entire brain and brainstem. Your brainstem manages your breathing and heart rate. Your brain manages senses like sight, sound and touch, and abilities like motor movement.

Because people’s brains drive these essential functions, someone is legally dead when they’re diagnosed with brain death. Healthcare providers follow established medical criteria (guidelines) to determine if someone is brain dead. For example, they rule out all other possible causes before they do specific tests that diagnose brain death.

Is brain death common?

No, it’s not. One analysis found that in the U.S., brain deaths accounted for 2% of all hospital deaths involving adults.

What is the main cause of brain death?

Many things may cause severe, permanent brain damage that leads to brain death. For example, your brain needs blood and oxygen to function, so any serious injury or illness that keeps blood and oxygen from your brain may cause brain death. Likewise, any injury or illness that damages blood vessels in your brain and causes bleeding may lead to it. Potential causes include:

• Traumatic brain injury.
• Intracerebral hemorrhage (brain bleed).
• Subarachnoid hemorrhage.
• Ischemic stroke.
• Heart attack.
• Hypoxic ischemic brain injury (HIBI), when your brain doesn’t get oxygen.
• Intracranial infections like meningitis or encephalitis.

What are the medical criteria for brain death?

The term “medical criteria” refers to the steps healthcare providers must take in diagnosing brain death. In the U.S., three medical societies collaborate on criteria. Before providers can do tests to diagnose brain death, they:

• Identify and treat any underlying condition that’s causing severe brain damage.
• Rule out potential issues and conditions that could be why someone has severe brain damage.
• Rule out conditions or issues that could cause symptoms that mimic brain death.

What tests are done to determine brain death?

Healthcare providers with special training in brain death do several tests. They may do tests more than once to confirm their initial diagnosis. If your provider suspects you have brain death, they’ll tell your family about the tests and what the tests might show. Tests include a physical examination, imaging tests like a brain MRI, an extensive neurological examination and an apnea test.

Neurological examination

In brain death, you don’t react to noise, lights or touch as you would before your brain injury. You may move, but your movement is involuntary, meaning you didn’t move on purpose. Providers doing a neurological examination to diagnose brain death will:

• Check your gag or choking reflex by touching the back of your throat.
• Check your eye reflexes by touching an eye with a cotton swab to see if you flinch, blink, close your eye or move your head.
• Check your pupils’ response to light.

Apnea test

If you have a catastrophic brain injury, you can’t breathe on your own and rely on mechanical ventilation (ventilators). In an apnea test, providers briefly stop ventilator support to see if you take a breath on your own.

What happens if tests show I am brain dead?

First, your healthcare providers will share and explain test results with your family, including that a brain death diagnosis means death. Your provider knows this is difficult news. They understand that your family will likely have many questions and concerns. Your providers will give your family time to take in what the results mean and answer questions.

Your providers will talk about the next steps, like removing the ventilator that is breathing for you. They may ask your family members if they want to see you and spend time at your bedside before the ventilator is removed.

What’s the difference between being in a coma and being brain dead?

If you’re in a coma, you’re unconscious, but you have some reflex response. For example, you might blink or turn your head when someone shines a bright light in your eyes. In brain death, you don’t have reflex responses. Likewise, comas aren’t always permanent. Most people emerge from comas within two weeks. In brain death, a person never regains consciousness due to permanent loss of brain function, which is completely irreversible.

Does anyone ever recover from brain death?

No, people don’t recover from brain death. Healthcare providers follow strict guidelines about assessing and testing for potential brain death. If tests indicate brain death, the person is clinically dead.

Can I prevent brain death?

No, you can’t because you may not be able to prevent any of the serious illnesses or injuries that lead to brain death. In some cases, immediate medical care may keep brain death from happening if you have a serious illness or an injury that affects your brain. But once your brain stops working, there isn’t a treatment that can prevent brain death from happening.

While you may not be able to prevent issues that can cause brain death, you can plan for what you want to happen if you’re sick or injured and you have brain death.

You do that by completing an advance directive. This is a legal document that outlines the kind of care you want in the event you can’t speak for yourself. For example, your advance directive could state you want to donate your organs after death, including brain death.