anoxic brain injury

What is an Anoxic Brain Injury?

Simply put, an anoxic brain injury deprives the brain of oxygen. Since oxygen is absolutely essential to human life, the gravity of this injury is obvious. Without oxygen, brain cells quickly die and important bodily processes fail. Anoxic brain damage can be caused by a variety of medical conditions or accidents. The severity of the damage is based on the length of oxygen deprivation and outcomes can vary widely. In this article, you’ll find an overview of the science and common prognoses associated with an anoxic brain injury.

The Science

By definition, an anoxic brain injury occurs when the brain receives inadequate levels of oxygen for an extended period of time. The brain uses approximately one-fifth of the body’s total oxygen supply. Low levels of oxygen mean that brain cells cannot function or communicate with one another. This impairs cognitive, physiological, and emotional processes.

  • There are three main modes of oxygen deprivation
    • Anoxic Anoxia: This type of condition exists if oxygen-rich blood is available, but it cannot get to the brain. Low blood pressure or blood clots are two common impediments.
    • Anemic Anoxia: In this instance, blood may not be able to carry enough oxygen. This is commonly seen in patients suffering from lung disease.
    • Toxic Anoxia: This occurs when a toxin, like carbon monoxide, enters the blood and prevent cells from utilizing oxygen.
  • After four minutes without oxygen, brain cells begin to die.
  • Certain areas of the brain require more oxygen than other areas. These oxygen-rich areas include the hippocampus, the cerebellum, the basal ganglia, and the cortex. Because of their extreme dependence on oxygen, these areas are especially sensitive to anoxic brain injury.

Common Causes

Anoxic brain injury can happen quickly. Some causes are related to underlying medical conditions. Other types of anoxic brain damage are caused by unfortunate accidents. A short list of common causes is provided below.

  • Choking
  • Hanging
  • Drowning
  • Suffocation
  • Cardiac arrest
  • Stroke
  • Electrical shock
  • Exposure to carbon monoxide
  • Heart arrhythmias
  • Bronchial asthma
  • Drug overdose


In general, a victim of anoxic brain injury will experience a loss of consciousness and move into a coma-like state. Even if the oxygen deprivation doesn’t last long enough to cause unconsciousness, the victim may still experience symptoms and lingering effects well after oxygen levels have been restored.

  • Short-term memory loss: The hippocampus (an especially oxygen-dependent part of the brain) is responsible for processing new information. Without oxygen, the hippocampus cannot develop new memories.
  • Problems with language and speech: Victims may use the wrong words, confuse words, or not understand words.
  • Poor visual functioning: Brain damage may result in the inability to recognize shapes, colors, or common objects.
  • Lack of coordination: Damage to the basal ganglia and cerebellum affect movement control. Patients may walk as though they are drunk, with bobbing and weaving motions.
  • Inability to perform daily tasks: Victims may not be able to complete simple physical movements like brushing their teeth or eating with utensils.
  • Inability to process high-level thinking: The victim’s reasoning, problem solving, and decision-making may be impaired.

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