A closed-brain injury is caused by a blow to the brain, such as from a vehicle collision, a fall, or a rapid acceleration. Closed-brain injuries tend to be less obvious than open brain injuries, and can be overlooked as there may be no visible signs of damage to the skull.
It is possible to suffer a TBI without being struck in the head. The inside of the skull has many bony ridges, and a violent acceleration or deceleration can cause the brain (which has the consistency of Jell-O) to impact them and cause significant damage.
If the impact is strong enough, the brain will bang against the inner wall of the skull and result in a coup injury. This can cause a contusion, or bruise. In some cases the brain will then rebound on the opposite side of the skull, causing another contusion on the other side of the brain – this is called a countercoup injury.
Depending on the force of the initial blow, these rebounds can happen several times. With each back-and-forth motion, the brain can sustain bleeding and tissue damage. It is not necessary for a person to lose consciousness in order to sustain a TBI. After sustaining the injury the victim may feel dazed or remain completely alert.
Complications From a Closed-Brain Injury
Frequently, following a brain injury, the brain swells due to an increased flow of blood to the injured tissue. Often this swelling is accompanied by a collection of water inside the skull. This collection of water, or edema, causes the pressure within the skull to increase, which can cause further damage to the brain.
The brain is supplied with blood through an extensive network of blood vessels. Following a brain injury, some of these blood vessels may rupture, which can lead to the formation of a pool of blood known as a hematoma. Like the edema, a hematoma increases the pressure inside the skull and can damage the brain.