The U.S. Department of Veterans Affairs/Department of Defense’s Clinical Practice Guidelines defines traumatic brain injury (TBI) as 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
• Any loss of memory for events immediately before or after the injury (posttraumatic amnesia)
• Any alteration in mental state at the time of the injury (e.g., confusion, disorientation, slowed thinking)
• Neurological deficits (e.g., weakness, loss of balance, change in vision, praxis, paresis/plegia [weakness/paralysis], sensory loss, aphasia [loss of speech]) that may or may not be transient
• Intracranial lesion (as seen from structural brain imaging, ...