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Image: “Drip.” by Guian Bolisay. Licence: CC BY SA 2.0

Definition of Brain Death

Brain death is defined as the irreversible cessation of the brain and brain stem functions, regardless of cause.

It is important to understand the physiological difference between a deep coma and brain death. A deep coma is characterized by the failure of basic reflexes. Pain stimulus is no longer perceived, and the aspiration has to be performed artificially.

Nevertheless, a coma can be about disruptions of 1 or more brain centers: Some areas can be irretrievably “dead” while other areas are mentally alive. Brain death, or rather general brain death, is a coma with a complete failure of the functions of:

  • Cerebrum
  • Cerebellum

If all 2 components failed, it can be considered that a patient is not conscious or is unconsciously alive.

By this definition, particular nerve cells or smaller areas of the brain can be still active. But they cannot bring back the central nervous entity of a functioning brain.

Etiology of Brain Death

  1. Severe head injury
  2. Hypertensive intracerebral hemorrhage
  3. Ischemia of brain
  4. Aneurysmal subarachnoid hemorrhage
  5. There are some drugs, such as neuroparalytic and anesthetic drugs, that can change the neurological and neuromuscular function as well as the electroencephalogram (EEG). 

Examination and Diagnosis of Brain Death

To undeniably identify the diagnosis of brain death, the examination of 2 experienced deaths is required. To ensure an impartial decision, they are not allowed to be part of the process of organ transplantation.

Signs of brain death

  1. The pupils of the patient do not respond to light.
  2. There is no response, e.g., blinking of the eyes on touching the surface of the eyeball of the patient.
  3. On touching the inner part of the throat near the uvula there is no gagging.
  4. The patient needs to be put on the ventilator.
  5. Skin remains warm when we touch it.
  6. Injection of atropine 1 to 2 mg intravenously will not increase the heartbeat more than 6/min. This is due to the non-stimulation of the vagus nerve.

Approach to brain death

1. Severe brain damage
2. Exclusion of other causes (for example intoxication, hypothermia)

Proof of symptoms:
1. Coma
2. Brain stem areflexia (for example pupil reflexes)
3. Failure of spontaneous breathing

Proof of irreversibility:
1. No change after 12-72 hours
2. Repetition of the proof of symptoms
Instrumental diagnostics (for example null lines-EEG for 30 minutes


If the patient is diagnosed with brain death, there are 3 possible scenarios:

  1. He remains connected to the machines till the natural decrease.
  2. It is decided by a living will or relatives that the machines are shut down.
  3. By consent for organ donation, the machines remain switched on until the removal of the organs (organ explantation).

Image: “Radionuclide scan of the head with Tc-99m Neurolite shows lack of intracranial blood flow and “hot-nose” sign from the diversion of blood flow to the external carotid arteries.” by JasonRobertYoungMD. License: CC BY-SA 4.0

Organ Donation

It is legally necessary to define brain death as a form of death; in order to remove donor organs from a person, the cardiovascular system should be working. Otherwise, the liver, kidneys, and the spleen can suffer damages from the shortage of oxygen within a short period of time.

The following diseases are characterized by a person’s death without the cessation of the heart:

  • Brain tumor
  • Craniocerebral trauma
  • Brain hemorrhage

Nevertheless, most accident victims never make a statement about whether or not they would like to donate their organs after brain death. This makes the possibility of help even more bleak. As the number of people awaiting a new organ increases, the problem continues to grow. 

Ethical Considerations

Many people do not completely trust the field of medicine. The idea of not being totally dead frightens them. Additionally, there is strong opposition to the concept of “brain death” and the arguments are quite viable. The critique encompasses religious concerns as well as medical doubts. Subsequently, 2 basic questions arise:

  • Can brain death be considered as similar to death?
  • Can brain death be undeniably diagnosed?

This is the reason why it is important to understand the brain functions. E.g., the observation of the Lazarus signs in a family member may be unwelcome. This includes the spinal cord reflexes which direct to arm and leg movements. A sensitive explanation of the processes involved helps the relatives to understand and accept the irreversibility of brain damage.

Additionally, it is possible that patients who are diagnosed as brain dead according to the process above can still make central-nervous body regulations. They sweat and digest, regulate their body temperature, and fight viruses. Men diagnosed as brain dead can have an erection. Pregnant women in the aforementioned state are able to bear an unborn life – the birth of healthy children is documented in more than 10 cases.

It is difficult to accurately diagnose brain death. The Roman-Catholic church, therefore, demands a null line EEG for 6 hours for a flawless diagnosis. Processes like the null line EEG, magnetic resonance imaging (MRT) or angiography must be performed to separate out patients with only brain stem damage. The demand to be under anesthesia during the organ removal “for safety” also seems to be reasonable.

It is hard to differentiate where life ends and death begins since there is no clear demarcation. This is especially difficult when someone close to us is affected. In the case of strangers, it may be easier to fathom.

Brain dead patients whose organs are removed cannot feel pain. Whether they want to be alive in this state or whether they would prefer to help someone else with their organs, should therefore, be determined when they are alive.

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