What is Anoxic Brain Injury?

Key Takeaways

Anoxic brain injury is a medical emergency that refers to brain damage that occurs when the blood oxygen supply to the brain is cut off. It can also occur when there is an inhalation of smoke or carbon monoxide.
Anoxic brain injury can be caused by strangulation, choking, suffocation, electrocution, drowning, smoke inhalation, carbon monoxide poisoning, head injury, cardiac arrest, heart attack, cardiac arrhythmia, very low blood pressure, stroke, substance abuse, including misuse of inhalants, drug overdose, severe blood loss, seizures, and complications of anesthesia.
Hypoxic brain injuries occur due to a lack of enough oxygen supply to the cerebral cortex (brain tissue). Traumatic brain injury (TBI) occurs due to a blow to the head, such as from a fall or motor vehicle accident.

Anoxic brain injury is a medical emergency that refers to brain damage that occurs when the oxygen supply to the brain is cut off. Please continue reading to learn more.

What is an anoxic brain injury?

The brain is a very active organ that needs a continuous supply of oxygen to function. In fact, the brain consumes about one-fifth of the body’s total oxygen supply.

When oxygen flow to the brain is interrupted, it is called cerebral anoxia. Oxygen deprivation causes loss of consciousness within seconds. Brain cells begin to die within 5 minutes. The resultant brain damage is called an anoxic brain injury.

Note: An anoxic injury can occur even when there is enough blood flow to the brain, such as with inhalation of smoke or carbon monoxide.

What’s the difference between anoxic brain injury and hypoxic brain injury?

Anoxic brain injuries occur due to a complete lack of oxygen delivery to the brain. Hypoxic brain injuries occur due to a lack of enough oxygen supply to the cerebral cortex (brain tissue). These terms are often used interchangeably. Doctors often refer to it as a hypoxic anoxic brain injury.

Is anoxic brain injury the same as traumatic brain injury?

Anoxic brain injuries are usually non-traumatic. In other words, an anoxic brain injury occurs without physical trauma. On the other hand, a traumatic brain injury (TBI) occurs due to a blow to the head, such as from a fall or motor vehicle accident. But sometimes, physical trauma can cut off oxygen flow to the brain, resulting in a hypoxic or anoxic brain injury.

Can cardiac arrest cause anoxic brain injury?

Cardiac arrest is one of the causes of anoxic brain injury. Some of the other common causes of an anoxic brain injury include:

Strangulation, choking, or suffocation
Electrocution
Drowning
Smoke inhalation
Carbon monoxide poisoning
Head injury
Cardiac arrest, heart attack, cardiac arrhythmia
Very low blood pressure
Stroke
Substance abuse, including misuse of inhalants
Drug overdose
Acute hemorrhage (severe blood loss)
Seizures
Complications of anesthesia

What are the signs and symptoms of anoxic brain injury?

Cerebral hypoxia can cause headache, dizziness, disorientation, confusion, trouble speaking, slurred speech, rapid or shallow breathing, stopped breathing, a bluish-gray tinge to the lips and skin, dilated pupils, convulsions, and unresponsiveness (this can be a minimally conscious state or complete loss of consciousness). Doctors use the Glasgow Coma Scale (GCS) to objectively describe a person’s level of consciousness.

Long-term effects of brain damage due to a hypoxicischemic injury include neurological disability consisting of memory loss, difficulty focusing or concentrating, cognitive impairment, poor judgment, personality changes, muscle spasms, muscle spasticity, swallowing difficulties, abnormal movements, problems with coordination and balance, vision problems, speech problems, and lack of bowel or bladder control.

The symptoms and long-term effects of a hypoxic or anoxic brain injury depend on the areas of the brain affected by oxygen deprivation.

Is an anoxic brain injury fatal?

A severe anoxic brain injury can be fatal. It can lead to seizures and coma. Brain cell death occurs after about 10 minutes of oxygen deprivation. This means there is no longer any electrical activity in the brain. After brain death, a person remains in a persistent vegetative state and needs life-support measures such as mechanical ventilation to breathe and stay alive.

Why do hands curl after brain injury?

Hands can curl after brain injury due to muscle spasticity (increased muscle tone or tightening of muscles with an inability to stretch or relax). This can occur after severe injuries to areas of the brain responsible for muscle control.

How do doctors diagnose anoxic brain injury?

Healthcare providers use imaging tests such as computed tomography (CT) and magnetic resonance imaging (MRI), angiography, electroencephalogram (EEG), and somatosensory evoked potentials to assess the severity of a hypoxic anoxic brain injury.

Can someone recover from an anoxic brain injury?

An anoxic or hypoxic injury to the brain is irreversible. This means it is not possible to bring back dead brain cells. Therefore, a full recovery from severe hypoxic anoxic brain injury is rare. However, many patients with mild or early-stage hypoxic anoxic brain injuries can make a partial recovery or even a full recovery of brain function. Treatments can help people who have suffered mild anoxic brain injuries.

The Brain Injury Association of America says treatment for brain injury is:

Acute (emergency or immediate treatment received in the intensive care unit of a hospital after the brain injury). For example, therapeutic hypothermia (lowering of the body temperature to reduce the brain’s demand and supply of oxygen.
Post-acute (long-term treatment for the lingering effects of the brain injury). For example, working with rehabilitation specialists such as physical therapists and occupational therapists to improve outcomes.

The type of care a brain injury survivor needs depends on various factors, such as the severity of the brain injury and their symptoms.

What is the survival rate for anoxic brain injury?

Survival rates after severe anoxic brain injury are, unfortunately, very poor. For example, anoxic brain injury is a significant cause of mortality in people who suffer a cardiac arrest. Survival after cardiac arrest is around 22% in-hospital and 10% out-of-hospital.

Studies have shown that the severity of the anoxic brain injury has a significant effect on survival rates:

Severe hypoxia is associated with mortality rates of 49% and disability rates of 69%
Mild hypoxia is associated with mortality rates of 30% and disability rates of 47%

Other studies have shown that 75% of patients have a poor outcome after hypoxic brain damage. Around 10% need further acute care in the hospital, 40% are discharged to nursing care facilities, 22% need subsequent rehabilitation, 18% return home, and around 10% die after an anoxic hypoxic brain injury.

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