Your doctor can often obtain all the necessary information to diagnose and treat a headache from a detailed series of questions and a careful physical exam. Occasionally, other diagnostic tests are helpful. These include: a CT scan of the head, brain MRI, sinus x-rays, or a lumbar puncture. Concerning features of a headache that may prompt your physician to order one of these tests include:

  • Sudden onset of the worst headache of your life
  • Acute change in your typical pattern of headaches
  • New severe headache in someone over the age of 50
  • Headache that is associated with a seizure or recent head traumax
  • Headache that occurs in the context of a fever, neck stiffness, confusion, weakness, numbness, sensitivity to light, or problems with coordination
  • "Whooshing" or pulsating sounds that are heard with a headache
  • Headaches that vary with changes in head or body position
  • Headaches that occur in people with medical problems such as cancer or AIDS
  • Headaches that are not responding to proper types and amounts of medications
  • Diagnostic tests that may be performed include the following:

    • A head CT scan is a quick and painless test in which X-rays are passed through the body at various angles to produce images of the skull and brain. It is sometimes used to look for an area of bleeding, swelling, mass, or abnormalities in the skull and sinuses. Although a CT scan can provide a quick and useful assessment of the brain's overall anatomy, it is not a very detailed test. People with claustrophobia usually do not mind undergoing a head CT. This test involves a relatively low level of exposure to radiation, slightly more than a chest x-ray.
    • A brain MRI, or magnetic resonance imaging, uses magnets and radio waves to create highly detailed pictures of the brain. Significantly more information is revealed than with a CT scan. An MRI takes much longer than a CT scan, sometimes up to an hour. It is necessary to lie still in a narrow tunnel during the entire study. For people with claustrophobia, this may be difficult. If available, "open MRI's"are a good alternative. If an open MRI is unavailable, a sedating medication may be helpful. People with pacemakers, some metal heart valves, and brain clips need special consideration before undergoing an MRIviii.
    • Sinus x-rays are useful to identify fluid or inflammation of the maxillary (cheek) and frontal (forehead) sinuses, a condition known as sinusitis that can sometimes cause headaches.
    • A lumbar puncture, or spinal tap, is a procedure in which a small needle is inserted between two bones of the lower spine (lumbar vertebrae) to remove a sample of the fluid that surrounds the brain and spinal cord. A lumbar puncture can help determine if a headache is the result of an infection, such as meningitis, bleeding, or increased pressure in the brain.

Sourced from:
viiiMRI Safety Update 2008:Part 2, Screening Patients for MRI
Shellock FG, Spinazzi A
AJR 2008; 191:1140-1149