Do I need an imaging study for my headache?

By Abraham J Nagy, M.D., FAHS

Key Points

  • Most people with headache do not need to get an imaging study.
  • There are certain situations when imaging studies are important to perform.
  • There are many different types of imaging studies that are used to look for different types of medical problems.

One of the most common reasons why people see their doctor for headache is because they are concerned that something is causing the pain. People are often worried about serious problems like brain tumors, infections, aneurysms, or blood clots. Fortunately, the majority of headaches are rarely ever caused by dangerous medical problems. In fact, studies show that most people who ever see a doctor for their headaches actually have migraine.

Migraine is caused by a complicated interaction between the brain and blood vessels in the face and head. The changes in the brain that happen during migraine cannot be seen by imaging studies, so for most people, an imaging study will not show anything and will look like the scan of someone who does not have headache. However, there are some situations when is important for doctors to make sure that dangerous problems are not causing the headaches.

Some reasons why your doctor would order a study?

  • You suddenly develop the worst headache of your life.
  • Your headache pattern suddenly changes.
  • You are over 50 and you have not had this kind of headache before.
  • You had a seizure with your headache.
  • Your headache started when you had a fever or other illness.
  • Your headaches are worse early in the morning or wake you from sleep.
  • You hear a funny “whooshing” or pulsating sound inside your head with your headache.
  • Your headaches started after a head injury.
  • Your headache occurs with exercise, sex, coughing, sneezing or going to the bathroom.
  • You have other symptoms with your headache like weakness, numbness, confusion, altered consciousness, coordination problems or difficulty speaking.
  • You have other medical problems like cancer or HIV.
  • Your headaches are not responding to medications.
  • You are overwhelmed with worry or fear about your headaches.

What kinds of studies are used to examine headache?

To evaluate if there are serious medical problems, there are basically two different ways to get an image of the brain. They both have their advantages and disadvantages.

A CT, or CAT, scan stands for computerized axial tomography. It takes pictures of your brain and skull with x-rays. It is a very quick study and takes only a few minutes. It is good at looking at very dense objects like bone or blood. Although it does give a good picture of the brain, it is not very detailed. CT’s are often used in the emergency room to see if a broken bone or a bleed in the brain is causing problems. CT scans do expose people to radiation, but it’s only a little bit more than a chest x-ray. If you are pregnant though, you should not have a CT, unless if circumstance are absolutely necessary.

An MRI, or magnetic resonance imaging, uses magnets and radio waves to create very detailed pictures of the brain. It takes much longer than a CT scan, about 30 to 60 minutes, but it provides a lot more information about the brain. People with pacemakers, metal heart valve. or certain brain clips cannot have an MRI because of the magnets used by the machine. If it is difficult for you to be in tight spaces, you should let your doctor know because during an MRI, you have to lie still in a narrow tunnel for the entire study. Sometimes it gets very noisy during the test and you may need earplugs.

Your doctor may want to give you contrast during these studies. This will give even more information about your brain—like if there is a tumor, an infection or a leak of fluid surrounding the brain. The contrast is injected through a vein in the arm. If you are having a CT, then the contrast contains iodine. You should tell your doctor if you are allergic to iodine or shellfish because you might have a bad reaction to the contrast. With MRI, the contrast contains a metal called gadolinium. If you have kidney problems, you should remind your doctor because the gadolinium may affect your kidney function.

In some situations, it’s helpful to look at the blood vessel in the brain. There are two types of blood vessels, arteries, and veins. Arteries bring blood into the brain and veins remove it. Both CTs and MRIs can exam these blood vessels by doing an angiogram (for arteries) and venogram (for veins). These studies are abbreviated as CTA/CTV and MRA/MRV. Angiograms are useful for looking for things like aneurysms or narrowing of arteries. Venograms help identify if there are clots which can cause a backup of blood flow in the brain.

CTA’s and MRA’s can be very useful, but cannot see things smaller than two to three millimeters (about the thickness of two dimes). In cases when doctors are very worried about an aneurysm or other blood vessel problem, they can order a conventional angiogram. This involves giving an injection of contrast through the groin and then following the contrast as moves through the brain using a fluoroscope which uses x-rays. There are some risks to doing this procedure—some people have had strokes during the exam, but this is very rare. If your doctor recommends this study, you should talk about the risks of doing the test. People can develop bruises around the groin and sometimes the study can even trigger a headache.

Are the reasons to not get a study?

  • 4% of people who go to doctors for headaches have migraine and imaging studies are unable to show what’s causing the headaches.
  • Doctors are usually able to diagnose and recommend medications by examining you and asking question.
  • CT’s or MRI’s will not be able to help manage the symptoms of headache. Nor are they likely to change your treatment for headache.
  • If your headache pattern has remained the same for months or years, then it is very unlikely that you headaches are caused by a serious medical condition. If you headache was cause by something dangerous, your symptoms would not remain the same for a long period of time.
  • If your headaches are well controlled by medications, then imaging is often unnecessary.
  • The cost of these studies must be taken into account. If you do not have insurance or your insurance will not cover the cost, you will be responsible and many of these studies are expensive.

Headache conditions can be severe and very painful, and imaging studies are helpful at diagnosing serious problem. Fortunately, most headaches are not caused by dangerous conditions. Although there are a lot of different ways to image the brain to find out what is causing the pain, imaging studies are usually unnecessary for most people.