The second of the secondary injuries possible as the result of a traumatic injury and after the primary brain injury has occurred, is brain swelling.
Brain Swelling is: The brain, like any other part of the body, swells after severe trauma. Because the brain is encased in the hard, unexpandable skull, however, brain swelling can have more serious effects than swelling in, say, an arm or a leg. In fact swelling is a major cause of damage to the brain after injury. Direct pressure can harm brain cells, or pressure may impair blood flow, cutting off oxygen. If the swelling is extensive it can squeeze the brain stem, disrupting normal life functions and leading to death.