Global brain injuries are the most severe types of brain injury possible. Recovery is difficult, but not impossible.
This article will cover the causes, symptoms, and treatments for global brain injury, plus explain what factors will impact a patient’s chances of recovery.
What is Global Brain Injury?
Global brain injury, also known as global ischemia or anoxia, refers to a complete loss of oxygen in the brain.
The brain uses oxygen to convert glucose into energy. Therefore, without oxygen, there is no longer any fuel to power brain cells. If this lack of power lasts too long, brain cells will die.
With global ischemia then, the brain is essentially starved of energy.
How long the brain can last without oxygen depends on the person. Some people, such as divers, train their brains to more efficiently use oxygen. These people can last several minutes without oxygen before experiencing irreversible brain damage.
For the general population, however, brain damage will occur after 3 minutes.
The longer the oxygen supply is interrupted, the worse the damage gets. The following is a general timeline of what happens when the brain is deprived of oxygen:
- After five minutes, permanent brain damage can set in
- After ten minutes, if the brain is still alive, the person will most likely fall into a coma after brain injury.
- After fifteen minutes, survival is unlikely.
Causes of Global Brain Damage
Any traumatic injury that leads to oxygen loss can cause global brain injury. The most common cause of global ischemia is cardiac arrest, but other causes include:
- Carbon monoxide poisoning
Effects of Global Brain Injury
The effects of global brain damage range from mild to severe, depending on how long the oxygen deprivation lasted.
When oxygen deprivation sets in, the body responds by increasing blood flow to the brain. This is meant to restore adequate oxygen and prevent damage.
Unfortunately, the body can only increase cerebral blood flow to twice the normal levels. If this is not enough, symptoms of global brain damage will appear.
The following are some of the most common effects of global brain injury.
1. Cognitive and emotional problems
If the damage was severe, those skills will be more seriously affected. There can also be changes in personality, including:
- apathy and lack of insight
Patients sometimes also have trouble with speech and language function, and struggle to find the right words or understand others. This is known as aphasia.
Finally, if the frontal lobe was damaged, the person can have their executive function impaired. Executive function refers to the ability to think and reason, to synthesize complex information, and to make judgments about how to act.
2. Blindness and other vision problems
The occipital lobe is particularly sensitive to low oxygen levels, and is one of the first areas of the brain to suffer damage when oxygen is lost. This leads to loss of sight and similar problems, also referred to as cortical blindness.
Global brain damage can also lead to a condition known as blind sight. This occurs when a person reacts to visual stimuli, such as an object in their way, without being conscious of it.
Conversely, damage to the occipital lobe sometimes causes Anton’s syndrome, in which a person with cortical blindness is not aware of their vision loss. Even though they might walk into objects, the person still believes they can see because the brain is creating a false image. This syndrome is serious but rare.
3. Hormonal problems
In severe cases, global brain injury can damage the person’s hypothalamus and pituitary gland, which will disrupt hormone production. This makes it impossible for the body to maintain homeostasis (i.e. a stable internal environment).
As a result, many neuroendocrine disorders will arise, such as:
- Excessive fatigue
- Autonomic dysfunction
- Muscle weakness
- Weight gain
- Low blood pressure
In the early stages, hormonal problems also trigger a condition known as diabetes insipidus, which causes increased thirst and excess production of urine.
4. Abnormal movements
Damage to the cerebellum, basal ganglia, or primary motor cortex often leads to problems with movement and balance.
Some of the most common movement disorders that occur after global brain injury include:
- involuntary writhing movements (athetosis)
- brief, jerky movements (chorea)
Global brain damage can also lead to muscle weakness and brain injury paralysis.
Treating Global Brain Injury
Treatment for global brain injury begins in the ICU where the person receives critical care to prevent as much brain damage as possible.
One new treatment for oxygen deprivation that some patients may undergo is therapeutic hypothermia. This is where cold packs are placed around the patient to lower their core body temperature.
Some evidence suggests that the cold has a protective effect on the brain and might aid recovery by decreasing the oxygen requirements of brain cells. This could give the brain more time before neurons starve and may explain why some people survive after drowning in freezing water.
This is still a controversial treatment, however, and carries risks of its own.
Factors that Affect Global Brain Injury Recovery
Once emergency treatment has been given, the next step is to wait and see whether the person will emerge from their coma.
There are several factors that help predict how well a person will recover from global brain injury. These include:
- Age. In general, the younger the person is, the better their chances are of a good recovery.
- Duration of oxygen deprivation. The more time the person was deprived of oxygen, the more severe their injury will be.
- Duration of coma. Similarly, the longer the person is in a coma, the lower the chances of a good recovery. This does not apply to medically induced comas, however.
- Pupil reaction. If their pupils do not constrict when bright light hits their eyes, that is a sign that their injury damaged their brain stem, which again will reduce the chances of a good recovery.
- Nerve responses. Doctors can electrically stimulate the nerves at the wrist and toes to see if the nerves are transmitting signals to the brain. If they are, that is a positive sign that could signal a good recovery.
Global Brain Injury Recovery
If the person regains consciousness after their global brain injury, recovery will start immediately.
Unfortunately, a global brain injury is harder to recover from than a traumatic brain injury with a similar amount of damage.
That’s because most traumatic brain injuries damage the connections between neurons (called axons). Therefore, the brain can rewire itself and create new connections to compensate.
But in a global brain injury, the neurons themselves are destroyed. This makes the brain damage much harder to overcome.
That doesn’t mean it is impossible to recover from a global brain injury, of course. But it will take more work.
Therapy for Global Brain Injury
Even though global brain injury is more severe than other brain injuries, the basic principle behind recovery is the same: activate neuroplasticity.
Neuroplasticity refers to the brain’s ability to repair itself after injury. You can engage it through repetitious exercise.
While neuroplasticity may not be as effective for global brain injuries as it is for other brain injuries, it still has the potential to help you recover your abilities.
Therefore, to recover from global brain injury, you should participate in the following therapies:
- Speech therapy to help you regain language and cognitive skills
- Physical therapy to help you overcome poor muscle control and weakness
- Occupational therapy to relearn skills such as bathing and eating
- Nutritional therapy to teach you what foods will fuel your brain and help it heal
In addition, consider trying hyperbaric oxygen therapy (HBOT) for brain injury.
Oxygen therapy is a relatively new treatment option, so most insurances do not cover it, but several studies have shown that it helps activate neuroplasticity in global brain injury patients.
Overcoming Global Brain Damage
Global brain injuries are serious medical conditions that require immediate treatment. Because every injury is unique, recovery is difficult to predict.
Generally, if oxygen can be restored quickly and the person regains consciousness within the first month, they have an excellent chance of making a full recovery.
The most rapid recovery usually happens within the first six months. However, recovery is still possible several years after an injury, though progress will be slower.
Even if recovery is slow, it’s still possible to make some improvements. The key is to begin therapy as early as possible and to continue activating neuroplasticity.
Featured Image: ©iStock/gorodenkoff