CT scan for seizures: everything you need to know

  • November 1, 2023
  • 4
In this article
A doctor monitoring a CT scan for seizures

Do you have a CT scan for seizures coming up? Your doctor might have recommended you have this test to help understand more about your seizures and what is causing them. CT scans are one of the more common tests that are used to diagnose epilepsy. 

If you’ve never had a CT scan before, you might feel a little uncertain about what to expect. Let’s learn more about CT scans for seizures, what they show, and why they’re useful. 

What is a CT scan?

A computerized tomography (CT) scan is a kind of advanced X-ray that has been used in the United States since the 1970s. The machine looks like a big doughnut. You lie on a bed, and you’re then moved inside. It uses X-rays to build up an image of the inside of your body. 

If your doctor suspects that you have epilepsy, the CT scan will mainly focus on your head and be used to create an image of your brain. 

Sometimes, a special dye will be injected into your body at the start of the test. This means blood in your veins stand out more clearly in the CT scan image. 

MRI scans - an alternative

Magnetic Resonance Imaging (MRI) is another way that doctors can create an image of your brain. MRI scans may create a more detailed image of your brain. But they also take more time and aren’t suitable for some people (including people who have metal implants or devices like pacemakers).

Why do we use a CT scan for seizure diagnosis?

A CT scan is a powerful way of seeing inside the brain. It can help identify possible causes of your seizures, including things like:

  • Brain damage
  • Malformed blood vessels
  • Tumors
  • Any physical abnormalities
  • Scar tissue
  • Problems with the circulation of blood or spinal fluid

CT scans might also be used if you are going to have brain surgery to treat your seizures. They can help the surgeons see exactly where in your brain they need to focus on. 

Do seizures show up on CT scans?

No, a CT scan won’t show a seizure happening. It can only show the physical structure of your brain - it doesn’t record electrical discharges when you have a seizure. 

A CT scan may be able to show where in the brain your seizures happen, based on blood flow. After a seizure, more blood may flow to where the seizure happened. So, if you were injected with a dye shortly after having a seizure then went to have a CT scan, the image might show that more blood has gone to one particular area in the brain. 

Suggested: What happens in your brain during a seizure?

But you may also have a completely normal CT scan after a seizure. People whose epilepsy is not caused by a physical abnormality in their brain will not have an unusual CT scan. 

This is why doctors normally recommend that you have a few different kinds of tests before diagnosing epilepsy - some tests won’t show anything unusual, but others will help identify the cause of the problem. 

Getting ready for a CT scan for seizures

If you have a CT scan for your seizures coming up, the team at the hospital will walk you through the steps and how to prepare. They might tell you to:

  • Avoid eating or drinking for a few hours before the test
  • Remove any metal objects you’re wearing
  • Wear loose fitting clothes (you may need to change into a hospital gown)

The procedure itself is normally fairly quick, and the whole process rarely takes more than 30 minutes. A technician at the hospital will be operating the machine from a room next door, and they can hear and see you, and you’ll be able to speak with them if you need. The Mayo Clinic has a great guide on what to expect from your CT scan. 

Are there any dangers with CT scans?

Hospitals have been using CT scans in the United States for around 50 years and they are seen as safe. As part of the process, you will be exposed to a small amount of radiation. If you are regularly exposed to radiation, this can have health consequences, but the amounts used in a single CT scan is safe for most people. 

If you are pregnant, then you must tell your doctor before having a CT scan for seizures as the radiation could affect your baby. Again, the risk is low, but it’s better to discuss it with them. 

Testing: Introduction to epilepsy tests

Another step toward diagnosis

After you’ve had your CT scan for seizures, a specialist will analyze the images and contact your doctor. Sometimes, the image will show a physical abnormality that could help with diagnosing epilepsy. But you could also have a normal CT scan after a seizure, so your doctor may decide to use another kind of test to learn more. 

If you have any doubts about your CT scan, don’t hesitate to ask your doctor or the technician at the hospital. They’ll be able to answer all your questions and make sure you feel comfortable having the test.

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