A head injury is any trauma that leads to injury of the scalp, skull, or brain. These injuries can range from a minor bump on the skull to a devastating brain injury.

Head injury can be classified as either closed or penetrating. In a closed head injury, the head sustains a blunt force by striking against an object. A concussion is a type of closed head injury that involves the brain.

In a penetrating head injury, an object breaks through the skull and enters the brain. (This object is usually moving at a high speed like a windshield or another part of a motor vehicle.)

Every year, approximately two million people sustain a head injury. Most of these injuries are minor because the skull provides the brain with considerable protection. The symptoms of minor head injuries usually go away on their own. More than half a million head injuries a year, however, are severe enough to require hospitalization.

Learning to recognize a serious head injury, and implementing basic first aid, can make the difference in saving someone's life. Medical advances in detecting and treating these injuries have improved the outlook for many people who injure their heads.

In patients who have suffered a severe head injury, there is often one or more other organ systems injured. For example, a head injury is sometimes accompanied by a spinal injury.

Accidents are the leading cause of death or disability in men under age 35, and over 70% of accidents involve head injuries and/or spinal cord injuries.

Common causes of head injury include traffic accidents, falls, physical assault, and accidents at home, work, outdoors, or while playing sports.

Some head injuries result in prolonged or non-reversible brain damage. This can occur as a result of bleeding inside the brain or forces that damage the brain directly. These more serious head injuries may cause:

• Changes in personality, emotions, or mental abilities
• Speech and language problems
• Loss of sensation, hearing, vision, taste, or smell
• Seizures
• Paralysis
• Coma