An anoxic brain injury occurs due to a total cutoff of oxygen supply to the brain. It is also referred to as anoxia. Human brain cells or neurons, begins to die off after only 4 minutes of total oxygen deprivation. Neurons cannot be recovered or re-grown. Once they die off, the result is permanent. Complete oxygen deprivation in the brain can cause widespread, irreversible damage and death within just a few minutes.
Medical professionals sometimes associate anoxic brain injury with hypoxic brain injury or hypoxia. However, the two classifications denote specifically different events, where an anoxic brain injury results from a TOTAL lack of oxygen to the brain and a hypoxic brain injury results from a partial lack, or inadequate supply, of oxygen to the brain. In medical research, doctors sometimes use the abbreviation HAI or Hypoxic-Anoxic Injury.
Anoxic Brain Injury Symptoms
Anoxic brain injuries may follow long periods of unconsciousness. A patient can become comatose or may enter a vegetative state as a result of a serious anoxic injury. Symptoms of anoxic brain damage following a period of unconsciousness can include:
- Headache
- Confusion/inability to concentrate
- Mood swings/irritability/depression
- Impaired balance/coordination
- Seizures
- Sleep disruptions/loss of consciousness/fainting spells
Classifications of Anoxic Brain Injury
Anoxic brain injuries (anoxia) typically fall under one of the four following general classifications:
- Anemic anoxia: This condition occurs when blood is no longer able to carry oxygen to the brain. Certain types of lung disease may contribute to very low blood oxygen levels. Therefore, the brain will not receive sufficient oxygen. In addition, chronic anemia, hemorrhages, and carbon monoxide poisoning may cause acute anemic anoxia.
- Toxic anoxia: Toxic anoxia is caused by toxins built up in the body which prevent the blood’s oxygen from being processed adequately in the brain. Carbon monoxide poisoning can also cause toxic anoxia.
- Stagnant anoxia: This occurrence is also referred to as hypoxic ischemic injury (HII). In HII, an internal injury, disease, or related condition prevents oxygen-rich blood from circulating to the brain. Common causes of HII are strokes, cardiac arrhythmia, and cardiac arrest.
- Anoxic anoxia: This injury is caused by a lack of oxygen concentration in the environment outside of the body. This is commonly experienced at high altitudes. Early stages are evident in inexperienced mountain climbers who become tired and weak as they climb to higher elevations. This is also why pressurized cabins or oxygen masks are necessary in high-altitude aircrafts.
Diagnosis and Treatment
Anyone experiencing of any of the symptoms listed above should seek medical attention and screening for an anoxic brain injury. After an initial examination, a physician who suspects an injury may order one or more of the following tests:
- CT scan of the head
- MRI (magnetic resonance imaging) of the head
- Electroencephalogram (EEG)—a test that measures the amount of electrical activity in the brain
- SPECT scans—a CT scan variant that examines specific areas of the brain for blood flow and metabolism
- Evoked potential tests—tests used to evaluate the visual, auditory, and sensory pathways
Depending upon the extent of the damage and severity of symptoms exhibited, patients may receive any combination of oxygen therapy and medications, as well as physical, occupational, and speech therapy sessions. Recovery can range from a few weeks to a few years, but lasting disabilities tend to exist in cases of severe injury.
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