Doctors do not use a CT scan to diagnose migraine. However, they may order a CT scan to help identify any underlying conditions that may be causing a person’s headache.

A computerized tomography (CT) scan is a medical imaging technique that combines a series of X-rays to produce cross-sectional images of body parts.

This article discusses what conditions CT scans can help diagnose, what people can expect from a CT scan, and how they can prepare for one. We also outline the potential risks of CT scans.

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Migraine is a neurological condition that causes moderate to severe headaches. Experts do not know the cause of migraine, though genetic and environmental factors likely play a role.

Medical professionals will not use a CT scan to diagnose migraine headaches. If a person is experiencing migraine, a CT scan will rarely show the cause of the pain.

However, a doctor may order a CT scan or similar imaging test to rule out other causes of a person’s headaches. The Radiological Society of North America (RSNA) states that a CT scan of the brain may help identify bleeding caused by the following conditions:

According to The Migraine Trust, there is no single test to diagnose migraine. To make a diagnosis, a doctor will likely:

  • ask about a person’s symptoms, including the type and severity of the headache pain
  • ask about a person’s medical history
  • ask whether there is any family history of migraine
  • perform a thorough neurological examination
  • consider other possible causes of the headaches to help rule out other conditions

A CT scan is a quick and painless test that medical professionals can perform on an outpatient basis. This means that a person can leave the hospital immediately following the procedure.

A CT scanner is a large, circular machine with an opening in the center for a bed or “table” to slide in and out. During the scan, a person may hear buzzing, whirring, or clicking noises as the machine rotates around the body, taking multiple images. Typically, the technician operating the machine will work in a separate room.

When a person is receiving a CT scan of their head, the machine will take a series of X-ray images of their head and combine them to give a full picture of their brain, blood vessels, and skull.

In some cases, medical professionals may inject a contrast dye into a person’s vein. The dye gives a better image of the blood vessels and other structures.

The RSNA provides general guidelines for people preparing for a CT scan and recommends the following:

  • wearing loose-fitting, comfortable clothing
  • removing jewelry, eyeglasses, or other metal objects
  • avoiding eating or drinking for several hours beforehand if receiving a contrast dye

A person should also notify their doctor or nurse of the following:

  • any medical conditions they have
  • any medications they are taking
  • whether they are pregnant or could be pregnant

When reviewing the results of a person’s head CT scan, the doctor will typically assess the following:

  • Various aspects of the brain:
    • Symmetry: Symmetry between the right and left sides.
    • Differentiation: A distinction between the white matter inside the brain and the grey matter on the surface.
    • Hypodensity: Less dense or “hypodense” areas that appear darker in comparison to surrounding tissues. These may indicate the presence of air, fat, or tumors.
  • Ventricles: Spaces within the brain that are filled with cerebrospinal fluid (CSF). A doctor will examine the ventricles for signs of dilation or contraction. Either may indicate disease.
  • Cisterns: Pools of CSF in the brain. A doctor will examine these for signs of blood.
  • Skull: A doctor will look for signs of fracture. Bone has the highest density on a CT scan, so will appear white.
  • Blood: This appears as bright white spots or areas in the brain.

After analyzing the person’s CT scan, the doctor will communicate the results. The doctor may do this during a face-to-face or telephone consultation.

A CT scan of the head exposes a person to a low dose of radiation. Having one or two scans may not cause any harm. However, repeated scans will expose a person to increasing amounts of radiation. Overexposure to radiation can damage cells and may increase the risk of cancer. As such, a person should not receive a CT scan unless it is necessary.

Since CT scans cannot help diagnose the cause of migraines, a person should not receive one for this purpose.

Although not a health risk, it is worth noting that CT scans can be expensive without insurance. The tests can cost between $500–1,000. A person should check with their insurance to make sure they will cover the costs of the test.

A doctor may recommend a CT scan if they suspect there may be an underlying medical condition triggering a person’s headache. Specifically, they may recommend a head CT scan if a person experiences one or more of the following:

  • headache pain that is sudden or severe, or accompanied by a feeling of something bursting inside the head
  • headache pain that differs from a person’s usual headache pain, particularly if the person is aged 50 years or above
  • headaches that occur after physical activity
  • headaches accompanied by additional symptoms, such as:
    • seizures
    • a loss of control
    • changes to speech or comprehension

Learn about Medicare coverage of CT scans here.

The following could help to alleviate a person’s migraine headaches:

Dietary changes and exercise may also help with migraine prevention.

A person should talk with their treatment team before making any changes to their treatment plan. They should also speak with their doctor about how their current treatment is working so that the doctor can make any necessary adjustments.

Learn more about migraine relief tips here.

CT scans are not a diagnostic tool for migraine. However, a doctor may recommend a CT scan to rule out underlying conditions that could cause migraine-like headaches.

CT scans are generally safe, though they do expose a person to low doses of radiation. Repeated CT scans could lead to radiation overexposure, which increases the risk of cell damage and cancer. As such, a person should talk with their doctor about whether they need a CT scan before receiving one.