What Is a Traumatic Brain Injury (TBI)?

In order to understand concussion/mild TBI, it is important to first understand the general characteristics of traumatic brain injury or TBI. The Department of Defense and the Department of Veteran Affairs define a TBI as follows:

A traumatically induced structural injury and/or physiological disruption of brain function as a result of an external force that is indicated by new onset or worsening of at least one of the following clinical signs, immediately following the event:

  • Any period of loss of or a decreased level of consciousness (LOC)
  • Any loss of memory for events immediately before or after the injury (post-traumatic amnesia or PTA)
  • Any alteration in mental state at the time of the injury (confusion, disorientation, slowed thinking, etc.) (Alteration of consciousness/mental state or AOC)
  • Neurological deficits (weakness, loss of balance, change in vision, paresis/plegia, sensory loss, aphasia, etc.) that may or may not be transient
  • Intracranial lesion

External forces may include any of the following events:

  • the head being struck by an object
  • the head striking an object
  • the brain undergoing an acceleration/deceleration movement without direct external trauma to the head
  • a foreign body penetrating the brain
  • forces generated from events such as a blast or explosion
  • or other forces yet to be defined

Not all individuals exposed to an external force will sustain a TBI, but any person who has experienced such an event and immediately showed the above signs and symptoms likely has had a TBI.