When would an MRI, CT or EEG be the right test for my child?
When we look for physical (organic) causes, we do certain tests. Imaging of the head is a medical way to take pictures, or images, of the brain. There are several types of imaging. The two tests used the most for headache are a CT scan (computed tomography) and an MRI (magnetic resonance imaging).
An MRI shows better detail than a CT scan. An MRI does not expose the child to radiation. An MRI can take over an hour to complete. Some children may require sedation or anesthesia to be still that long. In an emergency, CT scans are readily available and can be performed quickly. Some children have other health problems that may keep them from having an MRI, while a CT would be safe.
We do not recommend an EEG (electroencephalogram) as part of the headache evaluation. This test looks for abnormal brain waves. It is useful if seizures are suspected. It is not a useful test for a regular headache.
The doctor or nurse practitioner may order a test if your child has:
- Sudden, worst headache of his or her life (go to the emergency room)
- Sudden change in headache quality or pattern (drastic worsening or increase in frequency)
- Headache often beginning during sleep
- Seizure with headache
- Headache that started with a high fever or severe illness and is getting worse
- Recent, severe head injury with headache
- Headache triggered by exercise, certain positions or strain during coughing, sneezing or toileting
- Worrisome symptoms with headache (altered consciousness or speech, confusion, weakness, numbness or coordination problems)
- Headaches that begin in the back of the head and have other characteristics listed above.
Your provider will help decide what testing is right for your child. There is no lab test or imaging that “proves” a migraine diagnosis. Blood work and imaging are usually normal.
The doctor or nurse practitioner may not order a test. Reasons may include:
- At your visit, you and your provider will talk about the headaches. The provider will also do a physical and neurologic exam. This is usually all the information needed to treat most headaches.
- A CT or MRI rarely gives us information on how to treat headaches. The discussion of your headaches gives us the right information.
- It is reassuring if headaches are the same for months or years, without worsening or changes. Imaging is not likely to give any new information.
- If headaches are well controlled by medicines, imaging is not usually needed.
Other factors your provider will consider before ordering a study:
- Sedation — Young children often need sedation (a medicine to make them sleepy or calm) in order to lie still for long enough to get the MRI. There are always risks with sedation. Your provider must decide if getting the MRI is worth putting your child at increased risks by using sedation.
- Contrast — Sometimes your provider may want further details from the MRI. If so, a medicine called contrast is added to the blood to show more information about the brain. Children and adults can have reactions or allergies to contrast. Your provider will consider the risks of contrast when deciding whether or not to image your child’s brain.
- Radiation — X-rays and CT scans involve radiation. Radiation includes the transfer of energy to the body. This could cause injury to normal cells in the body. An X-ray or CT scan can be a very important medical tool, but when possible we avoid radiation to avoid this increased risk.