Experiences of different tests to diagnose epilepsy

There is no single conclusive diagnostic test for epilepsy. An important part of epilepsy diagnosis is a description of the seizure by the person who experiences it and someone who has seen it (because the person themselves might have been unconscious for all or part of it). The main diagnostic tests are EEG (ElectroEncephaloGram) and MRI (Magnetic Resonance Imaging). These tests can support a diagnosis of epilepsy but even if the results are normal, a diagnosis of epilepsy is not necessarily excluded. Other tests can also be used to aid the diagnosis. 

Here young people describe how they experienced the different tests they had for diagnosing epilepsy.

EEG records the electrical activity of the brain by picking up the electrical signals from the brain cells. Electrodes placed on the head record these signals on a computer. They only record electrical activity so the test is painless.

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Almost all of the young people we spoke with had had an EEG. Only one person hadn't and was still, five years after diagnosis, waiting for an appointment to have one. Quite a few people said they were scared before having an EEG because they didn't have much information about what it involved. A few did get more information and found this reassuring. One woman said that trying to relax and focusing on her breathing really helped during the EEG.

Sometimes during the EEG, a light is flashed in front of the person's face. Many people found the flashing light uncomfortable but this is a very important test to do to see if the person is 'photosensitive'. This is when seizures are triggered by flashing lights, or sometimes by certain geometric shapes or patterns. If the EEG changes during the flashing of a light, the technician will stop the flashing before a seizure develops.

Many young people said having an EEG was no big deal. One man said he was first scared of it but, in the end, it 'was a laugh'. Another said he looked like 'something out of Star Trek' with the electrodes on his head.

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The top tip young people wanted to give others going for an EEG was to take a hat to wear on the way home after the test because the sticky 'glue-like' material used to attach the electrodes will be all over your hair!

For a few people, the EEG results together with the eye-witness account of their seizures were conclusive to diagnose epilepsy. For some, the EEG results were absolutely normal and they needed other tests done or the EEG repeated later on. One man had an experimental EEG to find out more about the type of epilepsy he had. The experimental EEG lasted 2½ hours and he also had an MRI scan at the same time, but even that didn't detect what was wrong.

Sleep deprived EEG

The EEG is more likely to record abnormal brain activity if a person is tired or dropping off to sleep. 'Sleep deprived EEG' means having an EEG test while the person is sleeping. To help people sleep during the test, they may be asked to stay awake the night before. A mild sedative might also be used. One young woman who had normal results in the standard EEG was told she would need to have sleep-deprived EEG which showed abnormal activity.

Video telemetry

Video telemetry means having the EEG and being videoed at the same time. This usually lasts for a few days and requires a stay in hospital for this period of time. The electrodes are portable so that the person can move around the room. With video telemetry, the EEG can be compared with the video recording of possible seizures. This can give important information about whether seizures are caused by epilepsy and if so, whereabouts in the brain the seizure starts.


MRI (Magnetic Resonance Imaging) is a scanner that uses magnetic fields to take detailed images of the brain. It can find scars or other structural causes of epilepsy. MRI makes a loud noise but it is a painless test.

Because an MRI scan uses strong magnetic fields, metal objects in or near the machine can affect the scanner. Before having an MRI scan, all metal objects such as jewellery, piercings, coins, keys or hearing aids must be removed. 

Most young people had had an MRI scan. They described the scanner as a 'Smarties tube' and 'a tunnel'. Most had been worried about feeling claustrophobic inside the MRI scanner and described 'dreading it' and being scared beforehand.

Some people did feel claustrophobic in the MRI. Some said it was difficult to stay still and as soon as they were told to be still, they felt the urge to move. One man who had an MRI when he was a small child had got scared and got out of the scanner during the test.

Some people said that the two-way mirror inside the MRI scan was helpful because they could see the staff. Many were given headphones and the music played through them helped during this loud test. One young man, though, described feeling a bit panicky in the test and even more so because they played Spice Girls through his headphones!

Two women explained how the nurses had been joking with them during the test, and this had helped them to relax.

Young people's top tip for having an MRI scan was to ask to have headphones with music on during the scan, and to bring along a favourite CD!

For some, the MRI scan helped support a diagnosis of epilepsy. For others, however, the MRI tests came back as normal. One woman was told that, even though the results were normal, she might still have epilepsy because she was still having seizures.


A CT-scan (Computerised axial tomography) uses X-rays to take images of the brain. It is not painful and, unlike MRI, it doesn't make loud noises.

Young people who'd had a CT-scan described the machine as 'a giant polo' or 'a big washing machine'. Some were worried about feeling claustrophobic in the scan but one woman pointed out it was OK as you only go partway into the machine. Another described the CT scan as 'painless and quick'. During this test, when the X-rays are taken the person needs to be completely still, which some people found difficult.

Other tests

People we spoke with had also had other tests when their epilepsy was diagnosed. Many had blood tests (to exclude other problems) and a couple had ECG (electrocardiogram, to exclude heart problems). The doctors also tested their reflexes and eye-coordination.

Last reviewed May 2016.

Last updated May 2016.


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