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

Head injury is classified as either closed or open (penetrating).

• A closed head injury means you received a hard blow to the head from striking an object, but the object did not break the skull.
• An open, or penetrating, head injury means you were hit with an object that broke the skull and entered the brain. This usually happens when you move at high speed, such as going through the windshield during a car accident. It can also happen from a gunshot to the head.

There are several types of brain injuries, including:

• Concussion, the most common type of traumatic brain injury, in which the brain is shaken
• Contusion, which is a bruise on the brain

See also:

• Subarachnoid hemorrhage
• Subdural hematoma

Every year, millions of people have 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.

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

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 nonreversible 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:

• Coma
• Chronic headaches
• Loss of or change in sensation, hearing, vision, taste, or smell
• Paralysis
• Seizures
• Speech and language problems