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

Closed head injuries:

1. Do not penetrate the bones of the skull
2. Occur from 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
3. Can be more difficult to identify because there may not be visible signs of injury, such as bleeding or deformity

Serious symptoms usually develop within 24 hours after the injury. These may include:

1. Behavior changes
2. Difficulty paying attention
3. Personality changes
4. Restlessness
5. Slurred speech
6. Visual impairments, including blurred vision
7. Vomiting
8. Changes in the size of the pupils of the eyes, or in their response to light
9. Sleep disorders, including insomnia
10. Persistent fatigue or lethargy