Head injuries are a common type of injury. They can be either blunt or penetrating types of trauma. Head injuries can be external, internal or both. External head injuries often look severe because they may bleed heavily. However, internal head injuries (also known as traumatic brain injuries) are typically more serious than external head injuries because they can affect the way the brain functions.

Types of internal head injury include:

• Concussion. A loss of consciousness.
  
• Skull fracture. A break or crack in the skull.
  
• Contusion. Bruising of the brain.
  
• Diffuse axonal injury. Damage to the nerve cells in the brain.
  
• Hematoma. Bleeding or blood clot in the brain.

Head injuries are most often caused by accidents involving vehicles. However, many of these injuries can be prevented by taking proper safety precautions, such as wearing a seatbelt in an automobile or using protective helmets and face shields on a motorcycle or bicycle. Other causes of head injuries include falls, gun-shot wounds and injuries sustained while playing contact sports.

The signs and symptoms of head injury range from external bleeding and bruising to paralysis and changes in personality. The most common symptoms of a head injury include headache, short-term confusion, dizziness or lightheadedness, nausea and blurred vision, among many other possible symptoms.

These symptoms can go away after a short period of time, or they can become progressively worse. People who have a head injury and experience any of the following severe symptoms should contact emergency services immediately:

• Increasing sleepiness or confusion
  
• Persistent vomiting
  
• Paralysis of one or more limbs
  
• Inability to speak coherently
  
• Lack of coordination
  
• Clear fluid (cerebrospinal fluid) draining from nose or mouth

Physicians use imaging tests, such as x-rays, computed axial tomography (CAT) scans and magnetic resonance imaging (MRI), to assess the extent of a head injury. These can help physicians identify any damage that may have been sustained to the skull or brain.

Most people who have moderate to severe head injuries require some type of rehabilitation. Rehabilitation is designed to enable the patient to return to daily activities as soon as possible. It may involve help with the recovery of speech and movement. Many rehabilitation programs also aid patients with any psychiatric problems that may have developed as a result of their injury.