The Tell-Tale Signs Of Brain Death

When all neurological functioning irreversibly terminates in the brain due to a lack of blood flow, this is known as "brain death," explains the National Kidney Foundation

Brain death has a complicated history. Prior to the 1950s, death was primarily characterized by the absence of heart and lung function with loss of brain function taking place soon afterward (per Journal of Intensive Care). As advanced life support measures later came on the scene, however, this upended earlier notions of what was previously thought to constitute death. Over time, experts began to further prioritize a lack of neurological functioning rather than just the absence of cardiopulmonary functioning in determining a person medically dead.

According to an article published in StatPearls that was last updated in 2023, 2% of deaths across the country are due to brain death. Most often the result of physical trauma, brain death is sometimes alternatively termed "whole brain death" or "brainstem death" in different parts of the world. 

Here are the signs that indicate a person is experiencing brain death.

The signs of brain death and how they compare to coma

Brain death differs from a coma. A person who is brain-dead is considered dead, while a person in a coma is not. Although a comatose person is unconscious, the brain is still working and they are therefore not considered dead (per Better Health Channel). Oppositely, an individual who is brain dead may still be breathing, have a heartbeat, and even feel physically warm to the touch, but this is only because life support is maintaining these functions, not the brain. While recovery is possible for patients in a coma, this is not the case for brain-dead patients who are permanently deceased.

Tell-tale signs of brain death include no response to pain, the absence of a gag reflex when stimulated, and no patient respiratory function once the ventilator is turned off. The eyes also reveal a lot when it comes to brain death. Pupils that do not constrict in response to light, the absence of a blink response when the eyeball is touched, and a lack of eye movement when the head is shifted are all signs of brain death. The absence of a vestibulo-ocular reflex, in which the eyes fail to respond to ice water being dispensed into the ear, is also a sign of brain death. Finally, EEG neuroimaging technology will reveal no brain activity in patients who are brain dead.

How brain death protocols vary around the world

Researchers from the previously mentioned 2022 clinical overview published in the Journal of Intensive Care outline the current controversies that persist in the medical community surrounding brain death. In some countries, brain death is defined as all parts of the brain having suffered irreparable damage and therefore, the term "whole brain death" is used. In other countries, the sole death of the brainstem constitutes brain death rather than all parts of the brain, and therefore the term "brainstem death" is instead used. Although the majority of practitioners around the globe abide by whole brain death protocols, the researchers emphasize the need for continued discussion and refinement of what determines brain death in the medical community in order to establish guidelines that are as uniform as possible worldwide.

Cases of brain death can be particularly difficult for loved ones of the deceased. Because life support devices can make a patient appear as if they are functioning, this may make it hard for friends and family to comprehend that the person is permanently dead. This only further reinforces the importance of having knowledgeable and empathetic physicians in both neurology and critical care fields.