MRI tests and epilepsy

Magnetic resonance imaging (MRI) is a type of scan that can be used to check for any damage or problems in your brain that could cause seizures.

This page explains who might be offered an MRI scan, what information it gives and what to expect if you have one.

What is an MRI scan used for?

Some people have epilepsy because they have some damage or other problems in their brain. Damage to the brain may have been caused by scar tissue from an illness or a brain injury.

Some people can also have problems in their brain that they are born with. An MRI scan is used to find out if you have any type of damage to your brain.

How does an MRI scan show the damage?

The MRI scan uses a strong magnetic field and radio waves to create pictures on a computer of tissues, organs and other structures inside your body. These pictures can show up any damage in your brain.

Will I be offered an MRI scan?

If you have been diagnosed with epilepsy, the National Institute for Health and Care Excellence (NICE) says you should be offered an MRI scan, unless you have one of the following types of epilepsy:

You won’t usually need an MRI scan if you have one of these types of epilepsy, as they are not caused by damage to the brain.

You might be offered another MRI scan if:

  • The orginal scan results were unclear
  • Your epilepsy has changed
  • You have one of the epilepsy types above and your seizures have not stopped with the recommended treatment
  • You are being considered for epilepsy surgery

How can I get an MRI scan?

If you believe an MRI scan would help get the best treatment for your epilepsy, ask your GP, epilepsy nurse or specialist to arrange one for you. If they agree, NICE recommends an MRI scan should be done within 6 weeks of the doctor requesting it.

What does it involve?

The MRI scanner is like a tunnel. It’s about 1.5 metres (5 feet) long and is surrounded by a large circular magnet. You lie on a bed, which then slides into the open-ended scanner. During the MRI scan, images of your brain will be sent to a computer, which shows different types of brain tissue in different colours.

The MRI scan doesn’t hurt. The radiographer who does the scan might need to inject you in your hand or arm, with a harmless dye. This is to make the tissue show up as clearly as possible. A few people have had allergies to the dye, so the radiographer will ask if you have any allergies first.

The MRI scan can last between 15 and 90 minutes.

Is an MRI scan safe?

MRI scans are one of the safest medical procedures and there is no evidence that they cause harm to the human body. However, the powerful magnets used can affect metal implants and devices. For example, if you have a vagal nerve stimulator (VNS), pacemaker, or any other metal parts in your body, you may not be able to have an MRI scan.

Having a metal implant or device doesn’t always mean that you won’t be able to have an MRI scan. Medical staff decide on a case by case basis, if there are any risks. Sometimes further measures can be taken to ensure the scan is safe. For example, if you have a VNS fitted, your epilepsy specialist may switch it off before you have the scan.

If you are unable to have an MRI scan, your epilepsy specialist nurse or doctor may be able to arrange for you to have a different type of scan. MRI scans are also not usually recommended during pregnancy.

How will I feel during my MRI scan?

The MRI is noisy when it is scanning, but you will be given earplugs or headphones to protect your hearing. The inside of the scanner is like a hollow open-ended tube.

You might find this worrying if you are uncomfortable in confined spaces. You might be given a buzzer to hold, so that you can let the radiographer know if you feel uncomfortable while the scan is being done.

You might be able to listen to music, or watch a DVD while the scan is done, to help you to relax. A relative or friend might be able to go into the room with you.

If you feel nervous, or can’t keep still while the scan is being done, you could be offered medicine to help you relax or sleep. Young children and people with learning disabilities may need a very light general anaesthetic to make sure that they keep completely still during the scan. This is to avoid the scan pictures being blurred.

What will happen after my scan?

After your scan, a radiologist will study the pictures taken by the MRI. They will then send your results to the doctor who arranged your scan. This will generally be your epilepsy specialist. It usually takes a week or two for your MRI results to come through.

Find out more about MRI scans on

Published: May 2022
Last modified: October 2023
To be reviewed: September 2023
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