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What Is a Brain Injury?

An acquired brain injury occurs after birth—meaning it’s not hereditary, congenital or related to birth trauma. An acquired brain injury can be classified as mild (concussion), moderate or severe. This page will focus primarily on moderate to severe injury.

A TBI is caused by an external factor such as a bump, blow or jolt to the head, or a Penetrating injury (such as from a gunshot) to the head that disrupts the normal function of the brain. The severity of a TBI may range from mild (for example, concussion) to severe.

For children and teens the most common causes of traumatic brain injury are:

  • Motor vehicle accidents
  • Bicycle accidents
  • Falls
  • Abuse/Assaults
  • Sports accidents

Nontraumatic brain injuries happen when something inside the brain alters the health or normal functioning of the brain. Nontraumatic brain injuries can be caused by illnesses such as encephalitis and meningitis or can be related to a stroke or tumor.

Many factors can lead to nontraumatic brain injury including:

  • Brain tumors
  • Strokes
  • Encephalopathy, which is injury to the brain caused by disruption of other body functions such as from dehydration, liver or pancreatic illness or environmental toxins
  • Infections such as encephalitis or meningitis that cause inflammation in the brain

An hypoxic or anoxic brain injury occurs when there is lack of oxygen to the brain causing the brain cells to die. An hypoxic injury results from a partial lack of oxygen whereas an anoxic injury results from a total lack of oxygen.  

Children might experience a lack of oxygen due to:

  • Drowning
  • Choking
  • Cardiac arrest
  • Head trauma

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