Tearing - The sudden impact of the body colliding with another object (such as a car or baseball bat) may cause very delicate tissue in the brain to tear apart. Unfortunately, modern medical devices (x-ray, CT scan, MRI) often do not detect torn brain tissue. As a result, the injured patient may be given a clean bill of health when in fact there has been significant brain damage.
Bruising - Bruising, like tearing, is caused by impact to the skull. The impact forces the soft tissue of the brain into the much harder skull. The collision between the tissue and the skull may rupture small blood vessels allowing blood to escape into areas of the brain unsuitable for such blood. The unconfined blood places additional pressure on the brain tissue.
This Pressure May Cause Parts of the Brain to Stop Functioning
This pressure may cause parts of the brain to stop functioning. As the brain is responsible for operating the most basic bodily functions (such as breathing), it can be quite perilous for any part of the brain to shut down. Swelling - While swelling in most other body parts is not typically considered life threatening, swelling of the brain can be. When swelling occurs in other parts of the body, the tissue surrounding the injured area expands to relieve the pressure. The brain however is surrounded by the hard bone of the skull and therefore cannot expand to accommodate the swelling occurring inside. When the brain swells, the pressure inside the skull increases along with the likelihood of severe consequences as a result thereof.