Traumatic brain injury (TBI) is the term used to describe the damage to the brain suffered as a result of a sudden physical force. The human brain consists of billions of microscopic fibers, suspended in cerebrospinal fluid. While the exterior skull is smooth, the inner surface contains ribbing and pronounced bony structures. Impact with these inner surfaces of the skull causes tearing and bruising that results in brain damage.
Injuries occur when momentum of the brain causes it to impact against a skull that has been decelerated. Typically, TBI is caused by the impact of the head with an object, such as when hitting a windshield or the dashboard of a car. In such cases, the injury is considered to be a closed head injury. Closed head injury also may occur when the brain undergoes a severe forward or backward shaking, such as with infants who are mishandled or in cases involving whiplash suffered during an automobile accident. TBI can also be caused by a penetrating head injury, whereby an object such as a bullet penetrates through the skull and into the brain. Closed head injuries present unique challenges in litigation since they often will demonstrate no obvious external symptoms of injury, even though the damage to the brain can be severe. TBI does not refer to brain injuries or defects that are hereditary, congenital or degenerative, or induced by birth trauma, toxic substances, or disease-producing organisms.