From 2002 to 2012 the leading cause of TBI in the US was falls, followed by being struck by or against an object, motor vehicle collisions and assaults. Motor vehicle-caused collisions and suicides were the leading cause of TBI-related deaths.
Head Injury Types
Open vs Closed Head Injury
A brain injury can be open or closed. An open brain injury occurs when an object, for example a bullet, penetrates the brain and its protective coverings. Generally, the damage to the brain is localized, occurring in the area and path of the penetrating object.
In a closed head injury, the skull and its contents are not penetrated. Damage to the brain in a closed head injury is due to acceleration/deceleration forces causing the brain to move from front to back and side to side within the skull. This movement can cause both localized damage as the brain collides with the skull and damage throughout the brain due to stretching and shearing of neurons (nerve cells) throughout the brain.
Primary vs Secondary Injuries
Primary brain injury is the damage that occurs immediately at the time of the injury. Secondary injuries occur in the next hours or even days. Swelling of the brain, known as cerebral edema, is an example of a secondary injury. Injuries in other parts of the body can also lead to secondary brain injury.
Severity of injury is estimated by brain scans, duration of loss of consciousness and depth of coma, and extent of memory loss.
- Brain scans are used to show brain tissue damage, but there can be damage that does not show on the scan.
- The most widely used measure of level of consciousness is the Glasgow Coma Scale (GCS), which evaluates eye opening, motor response and verbal response. The GCS is often administered at the injury scene, as well as later in the hospital. The best score in the first 24 hours is used as the indicator of level of consciousness.
- It is not uncommon for a person who sustained a blow to the head to not remember the injury or having a conversation shortly after the injury. Post-traumatic amnesia (PTA) is the period of time after injury during which the injured person does not have consistent memory.