a) Traumatic brain injury (TBI)


Traumatic brain injury occurs as the result of some external force being applied to the brain in an accident or trauma. As a result of this blow or rapid movement, the brain may be torn, stretched, penetrated, bruised or become swollen. Oxygen may not be able to get through to brain cells and there may be bleeding.

The common mechanisms of TBI include:

Acceleration/ Deceleration injuries: Refers to injuries in which the head is in motion and then abruptly comes to a halt. For example, if a car hits a tree, the car suddenly stops, and the driver's head hits the steering wheel. The brain within the skull still has forward momentum and can hit the inner surface of the skull (which has bony edges) with some force, causing bruising, lacerations and bleeding.

Diffuse axonal injury:  The twisting motions or sudden changes in momentum that accompany some accidents may cause the bundles of nerve fibres to be stretched or shear. The term closed head injury is often used to describe this type of TBI, because the damage to the brain occurs as the result of these internal mechanisms, but usually with the skull remaining intact.

Penetrating injuries: This describes cases where some external object pierces the skull and comes in direct contact with the brain, thereby causing a TBI.

Other causes of brain trauma include falls, blows to the head, crushing injuries, electric shocks/ lightning strikes, and whiplash or violent shaking.


  • Motor vehicle accidents (i.e. drivers, passengers, pedestrians, motor bikes, cyclists) are responsible for 70% of severe traumatic brain injuries.

  • The peak incidence of TBI is among young males. 70% of TBI’s will involve young people aged between 16 - 24 years, and two thirds of those injured will be males.

  • A second peak is observed after 75 years. But there are different causes for these two age groups. The main cause among young people is road crashes, whereas the main cause for the elderly is falls.

More information

Self Study Module 1 at  1 An Introduction to Traumatic Brain Injury

Australian Institute of Health and Welfare