Common Types of Injuries to the Brain
The classic example of an open head injury is a gunshot wound with penetration of the skull, the protective layers of the brain, and the brain itself. Children/adolescents experiencing this unfortunate type of injury exhibit localized deficits associated with the area of the brain that is penetrated. They may never lose consciousness and may exhibit intact skills in areas of the brain which have not been damaged. In this respect, these children/adolescents may resemble individuals having had a stroke. Other types of open head injury may be more extensive, however.
Among children/adolescents with CHI, there are three basic types of injury to the brain that often occur. The first is a localized injury that might involve contusions (bruising) of the brain itself or development of a blood clot. Because of the way the brain is situated in the skull, when someone is struck very hard in the head it is relatively easy for the frontal and temporal area of the brain to hit against the inside of the skull, resulting in bruising. It is also relatively easy for vessels passing over the surface of the brain to be torn and thus generate a blood clot. These injuries are localized in that they occur in one area of the brain and are not generalized to the entire brain. These injuries may cause very specific deficits in functioning, such as weakness on one side of the body, impaired memory skills, or speech difficulties.
The second type of brain injury that may occur is termed diffuse axonal injury (DAI). The axons are part of the neurons that comprise the brain tissue. It is the axons that allow the neurons to communicate with one another through a chemical process. These axons can be relatively long and as such are susceptible to injury due to any kind of shearing force that may pass through the brain. When someone is struck on the head the force of the blow can be transmitted to the brain, which can create the type of shearing force that tears axons, with resultant death of the neurons. This type of injury is diffuse in the sense that it occurs all over the brain, although it tends to be more severe in some areas, such as the fiber tracts joining the right and left hemispheres. Evidence of diffuse axonal injury includes loss of consciousness (LOC) at the time of injury (due to stretching and tearing of brainstem fibers related to arousal) as well as a very slow recovery and generalized deficits due to the diffuse nature of the injury. It is often the DAI which has the most impact on a person's long-term functioning. Even in relatively mild injury it has been shown that DAI occurs; the distinction between a mild and severe injury can be thought of in terms of the extent of the DAI.
The third type of injury that can occur is secondary to the first two mentioned. The first two types of
injury, localized and DAI, occur instantaneously and there is nothing that can be done to change those
events. On the other hand, there are secondary effects on the brain which are the focus of attention from a
medical standpoint. For instance, if someone is not breathing well their brain may not be getting enough
oxygen or if there is very significant swelling of the brain, this could also create difficulties. If a blood clot
is growing in the brain it will likely have to be removed surgically. It is these kinds of difficulties that
concern neurosurgeons, and the prompt and adequate treatment of these problems is one of the reasons that
the fatality rate for severe TBI has diminished.
Table of Contents
From: Educating the Traumatically Brain-Injured Student