Serious head injuries may cause injuries to the brain. Head injuries are classified as either open or closed.

Open head injuries:

• Break or crush the bones of the skull.
• Can injure the brain and allow germs to come in contact with the brain.
• Are emergencies and require immediate medical care.

Closed head injuries:

• Do not break through the bones of the skull. The skull may have fractured, but the scalp is not cut or scraped.
• Are caused by a hard blow or impact that jars the brain within the skull. The rapid movement of the brain within the skull can:
  • Cause bruising, swelling, or tearing of the brain tissue.
  • Stretch, pull apart, or tear nerves or blood vessels, causing bleeding within or around the brain.
• Can be hard to identify. You might not be able to see an injury, because of bleeding or deformity near the injury.

Both open and closed head injuries may cause:

• An interruption in the way the brain normally works (concussion).
• Bruising and swelling of the brain tissue (brain bruise [contusion]).
• Bleeding within or around the brain, a life-threatening injury. Symptoms of this type of injury may be the same as those of a concussion. More serious symptoms usually develop within 24 hours after the injury. In rare cases, if the bleeding is slow, symptoms take longer to develop.