Magnetic resonance imaging and epilepsy

What does an MRI scan do?

When a magnetic resonance imaging (MRI) scanner is used to investigate epilepsy, it takes detailed pictures of your head. It can help to find if there is an abnormality that might be causing epilepsy, for example, scar tissue due to a brain injury. 

What does it involve?

The MRI will send images of your brain to a computer, which will show different types of brain tissue in different colours. The person who does the test is a radiographer. The radiographer may need to inject you in your hand or arm, with a harmless dye, to make the tissue show up more clearly. This could make you feel hot and flushed, but it will not hurt. 

Who is usually offered an MRI?

The MRI is a common scan used for individuals with epilepsy, particularly if any of the following applies to you: 

• you developed epilepsy before the age of two years or in adulthood; or
• you could have damage in your brain which may be causing the seizures; or
• you continue to have seizures despite taking medication.

The MRI will look for an anything unusual in a specific area of the brain, which may be the cause of the seizures. 

An MRI is not always used for people who have generalised seizures. This is because epilepsy is unlikely to be caused by damage to a part of the brain’s structure, when epileptic activity starts in both sides of the brain. In this situation the scan is unlikely to add anything to the diagnosis. 

Also, an MRI is not usually needed for people with some epilepsy syndromes, such as benign rolandic epilepsy. Again, this is because some epilepsy syndromes are not linked to with damage to the structure of the brain. 

MRI scans may not be suitable for people who have had a vagus nerve stimulator (VNS) or metallic clips implanted in their brain. There is a risk that the MRI scan could heat up the wires in the VNS or the metallic clips and cause damage to the surrounding tissue. 

Some people with a VNS or metallic clips choose to wear identity jewellery, so medical professionals would be aware of this, if the person ever needed to have an MRI scan. 

What happens during an MRI scan?

The MRI scan can take up to an hour and is very noisy. In the middle of the scanner is a hollow tube. You will be asked to lie on a table which is then moved inside the tube. This will scan your head and take pictures. Some people do not like being in the confined space of the tube and may be worried about the banging noises made by the machine. If this is the case for you, you may be offered medication to help you relax during the scan. 

The scanner is worked from behind a window by a radiographer. After the scan a radiologist will interpret the pictures taken by the MRI. These results will then be sent to the doctor who arranged your scan. This will usually be the epilepsy specialist. 

How do I get an MRI scan?

If you are concerned that there may be a cause for your epilepsy and think that an MRI scan could be helpful, talk to your GP or specialist about this. 

The NICE Guideline recommends that a person who needs an MRI should have the test carried out within four weeks of the doctor requesting it. Epilepsy Action supports this recommendation but knows that currently, due to the lack of MRI scanners and specialist staff, this does not always happen. We are actively campaigning for better services for epilepsy and hope that in the future, waiting times for MRI scans will meet the NICE recommendations.