Diffuse axonal injury occurs in about half of all severe head traumas, making it one of the most common traumatic brain injuries. It can also occur in moderate and mild brain injury. A diffuse axonal injury falls under the category of a diffuse brain injury. This means that instead of occurring in a specific area, like a focal brain injury, it occurs over a more widespread area. In addition to being one of the most common types of brain injuries, it’s also one of the most devastating.
Diffuse axonal injury isn’t the result of a blow to the head. Instead, it results from the brain moving back and forth in the skull as a result of acceleration or deceleration. Automobile accidents, falls, and child abuse such as Shaken Baby Syndrome are common causes of diffuse axonal injury.
When acceleration or deceleration causes the brain to move within the skull, axons, the process that allows neurons to send messages between them, are disrupted. As tissue slides over tissue, a shearing injury occurs. This causes the lesions that are responsible for unconsciousness, as well as the vegetative state that occurs after a severe head injury.
It is thought that diffuse axonal injury can occur in just about every level of severity, with concussion thought to be one of the milder forms. About 90 percent of survivors with severe diffuse axonal injury remain unconscious. The 10 percent that regain consciousness are often severely impaired.