What is a traumatic brain injury?

Traumatic Brain Injury (TBI) is defined as sudden, permanent damage to the brain caused by external, mechanical forces (e.g., a blow to the head suffered during a motor vehicle accident). Thus, there is a clear distinction between TBI and brain injury caused by internal events (e.g., stroke, anoxia, tumor), developmental disabilities (e.g., mental retardation, cerebral palsy, autism), and progressive illnesses such as Alzheimer’s Disease and Parkinson’s Disease.

When a TBI occurs, the brain may be penetrated from the outside, as in the case of a gunshot wound (open head injury), or not (closed head injury).

The term head injury is often also used to refer to TBI as well as to internal brain events such as anoxia (lack of oxygen to the brain due to cardiac arrest or cessation of breathing from other trauma), stroke (disruption in the blood supply to the brain due to either blockage or hemorrhage of one more blood vessels in the brain), tumor (a mass of new tissue), or encephalopathy (inflammation of the brain).