A traumatic brain injury is a penetrating head injury or blow or jolt to the head that disrupts brain function. The severity of traumatic brain injury can be relatively mild to severe. This can mean a change in consciousness lasting a short period of time, or an extended period of unconsciousness, amnesia and other long-term problems with brain function. Leading causes of traumatic brain injury are falls, automobile accidents, blunt trauma by an item hitting the head, and assault.