Traumatic Brain Injury (TBI): Condition Information

What is TBI?

TBI is a sudden injury from an external force that affects the functioning of the brain. It can be caused by a bump or blow to the head (closed head injury) or by an object penetrating the skull (called a penetrating injury). Some TBIs result in mild, temporary problems, but a more severe TBI can lead to serious physical and psychological symptoms, coma, and even death.1

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TBI includes (but is not limited to) several types of injury to the brain:

  • Skull fracture occurs when the skull cracks. Pieces of broken skull may cut into the brain and injure it, or an object such as a bullet may pierce the skull and enter the brain.
  • Contusion is a bruise of the brain, in which swollen brain tissue mixes with blood released from broken blood vessels. A contusion can occur from the brain shaking back and forth against the skull, such as from a car collision or sports accident or in shaken baby syndrome.
  • Intracranial hematoma (pronounced in-truh-KREY-nee-uhl hee-ma-TOH-muh) occurs when damage to a major blood vessel in the brain or between the brain and the skull causes bleeding.1,2
  • Anoxia (pronounced an-OK-see-uh), absence of oxygen to the brain, causes damage to the brain tissue.

The most common form of TBI is concussion.1 A concussion can happen when the head or body is moved back and forth quickly, such as during a motor vehicle accident or sports injury. Concussions are often called "mild TBI" because they are usually not life-threatening. However, they still can cause serious problems, and research suggests that repeated concussions can be particularly dangerous.3,4

A person who has a TBI may have some of the same symptoms as a person who has a non-traumatic brain injury. Unlike TBI, this type of injury is not caused by an external force, but is caused by an internal problem, such as a stroke or infection. Both types of injury can have serious, long-term effects on a person's cognition and functioning.5,6

TBI can happen to anyone, but certain groups face a greater risk for TBI than others. TBI among members of the military has become a particular concern in recent years because many military personnel in Iraq and Afghanistan have been exposed to such TBI hazards as improvised explosive devices. Head and neck injuries, including severe brain trauma, have been reported in 1 out of 4 military members who were evacuated from those conflicts.7 For more information about brain injury in the military, visit the Defense and Veterans Brain Injury Center websiteExternal Web Site Policy.


  1. Centers for Disease Control and Prevention. (2012). How many people have TBI? Retrieved June 12, 2012, from
  2. American Academy of Family Physicians. (2010). Traumatic brain injury: Overview. Retrieved May 24, 2012, from Web Site Policy
  3. Centers for Disease Control and Prevention. (2011). Concussion and mild TBI. Retrieved May 24, 2012, from
  4. Centers for Disease Control and Prevention. (2010). Concussion: Feeling better. Retrieved May 24, 2012, from
  5. National Institute of Neurological Disorders and Stroke. (2012). Stroke information page. Retrieved June 14, 2012, from
  6. National Institute of Neurological Disorders and Stroke. (2011). Meningitis and encephalitis fact sheet. Retrieved June 14, 2012, from
  7. Hoge, C. W., McGurk, D., Thomas, J. L., Cox, A. L., Engel, C. C, M.P.H., & Castro, C. A. (2008). Mild traumatic brain injury in U.S. soldiers returning from Iraq. New England Journal of Medicine, 358, 453–463.

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