Anoxic brain injury can result from oxygen deprivation to the brain.
A diffuse axonal injury frequently results from traumatic deceleration injuries, even when there is no direct impact on the head. A serious diffuse axonal injury is more likely to occur when there is an actual impact, such as the head hitting a windshield. Sudden acceleration and deceleration can create rotational forces that impact the brain, and the forces are greater when the head hits something and suddenly stops. Many different layers of matter make up the brain, with the layers varying in density and weight. When the brain is subjected to sudden acceleration or deceleration, the different layers of the brain accelerate/decelerate at different rates. Injury to nerve fibers (axons) can occur during the acceleration/deceleration and result in disruption to the regular communication and chemical processes in the brain.
Direct blows to the head, gunshot wounds, violent shaking of the head, or force from a whiplash-type injury are all causes of concussions. A concussion is the most common type of traumatic brain injury. Concussions may or may not cause a brief loss of consciousness.
A contusion is a bruising of the brain that may cause bleeding (hemorrhage) and can result from a direct impact to the head. Large contusions may require surgical removal.
A coup-countrecoup injury involves contusions both at the site of impact and at the opposite side of the brain. This type of injury frequently occurs when a moving head hits a stationary object such as a dashboard. At impact, the brain is injured on the opposite side of the point of impact.