Anoxic and Hypoxic Brain Injury

Brain Injury Imaging Picture

What are Anoxic or Hypoxic Brain Injuries?

Unlike traumatic brain injuries, in which brain damage is induced by direct physical trauma, anoxic and hypoxic brain injuries are brain injuries characterized by a lack of oxygen being provided to the brain. Anoxic and hypoxic brain injuries are commonly associated with strokes, although strokes are not the only causes of these this type of brain injury.

  • Anoxic brain injuries are caused by a complete lack of oxygen being provided to the brain, which results in the death of brain cells after approximately four minutes of oxygen deprivation.
  • Hypoxic brain injuries are brain injuries that form due to a restriction on the oxygen being supplied to the brain. The restricted flow of oxygen causes the gradual death and impairment of brain cells.

Causes of Anoxic and Hypoxic Brain Injuries

  • Hypoxicischemic injury, also known as stagnant anoxia, may:
    • Occur when oxygen-carrying blood cannot reach the brain, resulting in oxygen deprivation.
    • Be caused by strokes, but can also be caused by other pulmonary conditions, such as cardiac arrest or cardiac arrhythmia.
  • Anemic anoxia: Anemic anoxia occurs when the blood cannot properly carry enough oxygen or if there is not enough blood in the body itself to support the oxygen needs of the brain.
  • Toxic anoxia: Toxic anoxia occurs when chemicals or poisons hinder the ability of the brain to receive oxygen from blood cells.
  • Anoxic anoxia: Anoxic anoxia is caused by the lack of oxygen in the air, resulting in suffocation.

Symptoms of Anoxic and Hypoxic Brain Injuries

Anoxic and hypoxic brain injuries often cause an initial loss of consciousness, which can be short-term or long-term depending on severity and length of oxygen deprivation. Initial loss of consciousness may result in a comatose state. Other symptoms of an occurring anoxic or hypoxic brain injury occurring may include slurring and difficulties with speech, confusion and disorientation or facial drooping.

Upon regaining consciousness, the effects and symptoms are often similar to that of a traumatic brain injury, depending on severity of the injury. More severe anoxic or hypoxic brain injuries may leave the patient in a vegetative state. The effects of an anoxic brain injury may include:

  • headache
  • difficulty coordinating balance
  • blurred vision in one or both eyes
  • milder vision problems
  • seizures
  • changes in sensory perception
  • trouble speaking and swallowing           
  • changes in sleep pattern
  • lack of bowel and bladder control
  • changes in sexual function
  • motor impairment 
  • personality changes
  • difficulty forming sentences 
  • confusion
  • trouble communicating
  • difficulty with reason, focus and logic
  • memory impairments
  • depression
  • poor concentration
  • mood swings
  • limited attention span
  • disorientation
  • forgetfulness
  • acting inappropriately

Prognosis of Anoxic or Hypoxic Brain Injuries

Projecting the recovery and care for anoxic or hypoxic brain injuries is difficult because each case is unique. A full recovery from severe anoxic or hypoxic brain injury is rare, but many patients with mild anoxic or hypoxic brain injuries are capable of making a full or partial recovery. Furthermore, symptoms and effects of the injury are dependent on the area(s) of the brain that was affected by the lack of oxygen.