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Coma → brain death. Coma → vegetative state.

Updated: May 29, 2022

Studying the "Study of Consciousness" (Stanislas Duanne) can further deepen your understanding of coaching theory.

I am studying to add a unique flavour to "unconscious rewriting".

This series of blog posts are my study notes. This time, the theme that follows the unconscious and conscious

I will write a "sign of consciousness".


Disorders of neurological consciousness can be organized as shown in the figure below.

Most patients begin with a "coma" (derived from the ancient Greek word "Kaua", which means "deep sleep"). Coma usually occurs within minutes to hours after a brain injury.

There are various causes, such as head injury (typically a car accident), stroke (rupture or obstruction of a blood vessel in the brain), oxygen deficiency (cardiac arrest, carbon monoxide poisoning, a water accident, etc.), to supply oxygen to the brain. Also, loss), poisoning (which can also be caused by heavy drinking), etc.

The patient lies with his eyes closed and unresponsive, does not wake up no matter how much stimulation is given, and shows no awareness of himself or the environment.

It is distinguished from temporary fainting, concussion, and deafness.

When brain-dead patients are measured by positron emission tomography (PET) or ultrasonic Doppler method, we can see that the metabolism of the cortex and the perfusion of blood to the brain are interrupted.

Brain death can be diagnosed in 6 hours to a day if it is not affected by hypothermia or drugs or toxicants.

Neurons in the cortex and thalamus quickly alter and disappear, and the lifelong memory that defines the person is permanently lost.

Therefore, brain death is irreversible. No technology can regenerate degraded cells or molecules.

In most countries, including the Vatican, death is identified by brain death.

The distinction between coma and brain death is that some synchronized response to the body continues in a coma. Many of the higher-order reflex reactions have not been lost.

For example, most patients in a coma get sick when their throat is irritated. Also, when exposed to intense light, the pupil contracts.

These reactions indicate that some of the unconscious neural circuits deep in the brain stem are still functioning.

The brain waves of an unconscious patient continue to fluctuate at a slow pace.

You can see low-frequency brain waves similar to those seen during sleep and under anaesthesia.

Many of the cortex and thalamus cells are still alive and active, but the network is inadequately placed.

However, the cells are still active, so the normal rhythm may someday return.

Thus, the brain of an unconscious patient is active. Their cortex produces fluctuating brain waves but cannot escape "deep sleep" and arouse consciousness.

Coma usually does not last long. However, if complications such as infection are avoided, most patients will gradually recover within days or weeks.

The first sign of this is usually the recovery of the sleep/wake cycle. After that, most comatose patients regain consciousness, communication skills, and the ability to take intentional actions.

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