Brain Dead: Symptoms, Diagnosis & Treatment

Brain dead means there is an irreversible loss of all brain function, including the brain’s control over breathing, heartbeat, blood pressure, movement, and hearing. In medical and legal terms, this means the person has died.

A person who is brain dead cannot maintain the body’s vital functions without life support. The person also cannot breathe independently or respond to stimuli.

Brain death is confirmed by one or more physicians, such as a neurologist or neurosurgeon, based on an evaluation of brain injury and tests that assess brain activity. The diagnosis must be carefully confirmed because other conditions can cause similar signs.

Main symptoms

Symptoms that suggest a person is brain dead include:

• No spontaneous breathing, meaning the person cannot breathe on their own and breathing is maintained with machines.

• No pain response or response to stimuli, such as a needle prick or touching the eyeball.

• No pupil constriction when the eyes are exposed to light.

• No gag reflex when something is placed in the upper throat.

When these symptoms are present, doctors must confirm the diagnosis by performing tests to determine whether the person is brain dead.

Can a person who is brain dead hear?

It is still unknown whether a person who is brain dead can hear.

A study conducted in the United States found that some people might still be able to hear even though they do not respond.

However, that study is not directly related to being brain dead, and more research is needed to better evaluate this possibility.

Confirming a diagnosis

Brain death must be confirmed by two different physicians, such as a neurologist and a neurosurgeon, based on clinical evaluation and tests conducted on separate days.

These tests not only determine the absence of brain activity but also help exclude other conditions that can mimic brain death, including drug or medication overdose, poisoning, hypothermia, hypothyroidism, brainstem encephalitis, hepatic encephalopathy, or Guillain-Barré syndrome.

According to the 2023 consensus practice guideline from the American Academy of Neurology, the American Academy of Pediatrics, the Child Neurology Society, and the Society of Critical Care Medicine, any potentially confounding conditions must be ruled out before confirming brain death or death by neurologic criteria.

Main tests

The main tests and exams used to confirm that a person is brain dead are:

• Pupil reaction testing with a flashlight to check whether the pupils constrict when exposed to light.

• Eye sensitivity testing to see whether the person reacts when a tissue or cotton is touched to the eyeball.

• Assessment of response to stimuli by applying pressure to the forehead and nose.

• Eye movement testing by placing cold water in each ear to see whether the eyes move in response.

• Gag reflex or cough reflex testing by inserting a small, thin plastic tube into the trachea.

• An apnea test, which checks whether the person can breathe independently when the breathing machine is turned off for a short period.

• Testing for response to verbal stimuli to assess whether the person can speak or respond.

• Assessment of whether the heart rate increases by more than 5 beats per minute after a 1 to 2 mg dose of atropine is given directly into a vein.

• An electroencephalogram to check whether the brain has any electrical activity.

• Cerebral angiography to check for blood flow in the brain.

• Transcranial Doppler to confirm the absence of blood flow in the brain.

• Cerebral perfusion scintigraphy to assess whether there is blood flow and brain metabolism.

Before beginning tests to confirm brain death, doctors must first evaluate and rule out other possible causes of the symptoms.

Possible causes

Brain death occurs when conditions disrupt the brain’s supply of blood or oxygen, leading to swelling of the brain, a condition known as cerebral edema.

When this happens, the skull cannot expand, so it puts pressure on the brain and reduces brain activity.

Over time, if the swelling is not treated, irreversible brain damage can occur and put life at risk.

Risk factors

The main factors that can increase the risk of a person becoming brain dead are:

• Head trauma or subarachnoid hemorrhage.

• Heart attack or cardiopulmonary arrest.

• Stroke or intracerebral hemorrhage.

• Brain swelling or increased intracranial pressure.

• Brain infections, such as encephalitis.

A brain aneurysm or a brain tumor can also increase the risk of brain death.

Is there a cure?

Brain death is not curable because the brain has suffered damage that cannot be reversed. This means the brain is no longer functioning and cannot start functioning again.

However, even when the brain no longer has any activity, other organs such as the kidneys, liver, and heart may continue to function for a short time while the person is kept “alive” by machines in the hospital.

Treatment options

There is no treatment for a person who is brain dead because it is an irreversible condition.

However, the person’s vital functions can be maintained in the hospital with life support machines, even though the person is legally and clinically considered dead because there is no chance of recovery.

A person who is brain dead may be kept “alive” with machines for as long as the family wishes, although this is generally only done for a period of time when the person is an organ donor, so the organs can be removed for transplant into another patient.

According to Organdonor.gov, once doctors confirm brain death and record the time of death, organ donation may then be possible if the person is an eligible donor.

Is being brain dead the same as a coma?

When a person is confirmed to be brain dead, it means that no part of the person’s brain is functioning anymore and the person is legally considered dead.

This is different from a coma or a vegetative state because, in those conditions, there is still some brainstem function and possibly some activity in other parts of the brain, so the person is legally considered alive.