This information is relevant to people who live in the UK.
- Diagnosing epilepsy
- EEG (electroencephalogram) tests
- CT scans (computerised tomography)
- MRI scans (magnetic resonance imaging)
- Blood tests
There are a number of medical conditions that can cause symptoms similar to epilepsy, which can make it difficult to diagnose. So, an epilepsy specialist will make a diagnosis based mainly on your symptoms.
You can help the specialist to make a diagnosis by:
- Taking a detailed diary of your seizures to your appointments, with dates, times and a description of what happened, and how you were feeling before and after
- Taking someone who has seen your seizures, or a written description from someone who has seen your seizures, to your appointments
- Taking some video clips of your seizures to the appointment, if this is possible
Tests used in the diagnosis of epilepsy
The epilepsy specialist may arrange for you to have some tests at the hospital. These include EEG tests and CT or MRI scans. None of these tests can prove that you do or do not have epilepsy. However, they can sometimes give useful information, such as the cause of your epilepsy and the type of seizures you have.
An EEG test measures the electrical activity that is happening in your brain. During the test, an EEG specialist places harmless electrodes on your scalp, using a special glue or sticky tape. The electrodes are connected to the EEG machine, which records the electrical signals in your brain onto a computer.
An EEG only shows what is happening in your brain at the time the test is being done. It is not able to show what has already happened or what is going to happen in the future. So, if there is no epileptic activity in your brain at the time the test is done, the EEG will show clear results. However, EEG tests can sometimes provide useful information to doctors
A CT scan is a type of X-ray that shows the physical structure of the brain. During the scan, you'll usually lie on your back on a flat bed. The CT scanner, which looks like a giant thick ring, will rotate around your head, taking X-rays.
A CT scan doesn’t show if you have epilepsy. However it may show if there is anything in your brain, such as a scar, or damaged area, that could cause epilepsy. Not everyone will need to have a CT scan.
An MRI scanner uses radio waves and a magnetic field to show the physical structure of the brain. During the scan, you lie inside the MRI machine, which is a very large tube.
An MRI scanner is more powerful than a CT scanner. It has a higher chance of showing something in your brain that could cause epilepsy. Not everyone will need to have an MRI scan.
These are used to check your general health, and to look for any medical conditions that might be causing epilepsy. They can also be used to find out if your seizures are not caused by epilepsy, but another medical condition, such as diabetes.
Epilepsy Action would like to thank thank Dr John Paul Leach, consultant neurologist, Southern General Hospital, Glasgow for his contribution.
Dr John Paul Leach has declared no conflict of interest.
This information has been produced under the terms of The Information Standard.
Updated April 2014To be reviewed April 2017