Diagnosis of a head injury can be made by a physician or paramedics, depending on the circumstances of the injury. In some cases, the evidence of a head injury is obvious – the person is unconscious and has clear signs of external injuries, for example.

If paramedics are called to the scene of an accident of a potential head injury, they will assess the extent of the injury using a standardized scale called the Glasgow Coma Scale. This is a three-part, 15-point physical assessment that tests the patient’s ability to open the eyes, speak coherently and move the arms and legs. A score of three to eight on the scale means that the patient has sustained a severe head injury, nine to 12 indicates a moderate head injury and 13 to 15 means that the head injury is mild. Depending on the severity of the injury, the patient will be transported to a hospital where further tests will be performed.

In cases of apparently mild head injuries, a person can seek medical attention, during which a physical examination and a medical history will be conducted. The patient will be asked questions related to the circumstances of the head injury and on the nature of their symptoms. It is important that the patient discuss any and all symptoms that could be related to the head injury. The possible symptoms include headaches, mood swings, irritability, vomiting or disturbances in vision or other senses.

A physician may recommend the following tests to assess the extent of the head injury:

• X-ray. A painless test in which an image is created of part of the body by using low doses of electromagnetic radiation that are reflected on film paper or fluorescent screens. An x-ray is effective at diagnosing skull fractures, although it is less effective at diagnosing specific problems within the brain. For this purpose, a computed axial tomography (CAT) scan or magnetic resonance imaging (MRI) may be used.
  
  
• CAT scan. A noninvasive or minimally invasive test that uses a rotating x-ray device to create three-dimensional, cross-sectional images (or slices) of different body parts, including the brain and skull. CAT scans can be used to diagnose numerous conditions and complications which may arise from a head injury, such as blood clots, hematomas and skull fractures. They can also be used to guide a biopsy.
  
  
• MRI. A noninvasive procedure that uses powerful magnets and radio waves to produce clear, cross-sectional or three-dimensional images of many bodily tissues. MRIs are particularly useful in cases of head injuries because they can assess how the brain is functioning. This type of MRI is called a functional MRI (fMRI). During an fMRI, the patient may be asked to perform a task while the machine scans the brain and records brain activity. This information can then be used to determine which parts of the brain may be damaged.