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Tests before epilepsy brain surgery for children

These pages are about surgery in the UK. If you are looking for information about surgery in another country, please contact your local epilepsy organisation.

To find out if your child will be suitable for surgery, the epilepsy team at the CESS centre will thoroughly assess them and advise whether surgery is possible. They will also recommend where it should take place.

As part of the assessment, the CESS team will ask for your child to have a number of tests, which could include:

Information about the tests

Electroencephalogram (EEG)/video telemetry

The EEG machine records the electrical signals from the brain on a computer. During the EEG, a technician places harmless electrodes on your child’s scalp, using a special glue or sticky tape. The electrodes are then connected to the EEG machine. 

In video telemetry, a video recording is done at the same time as the EEG. This means that if your child has a seizure, doctors can see exactly what happens. It is important all children that may benefit from surgery have video telemetry. This is to find out exactly where in the brain your child’s seizures are coming from. An EEG/video telemetry can be done while your child is awake or asleep, or both.

Magnetic resonance imaging (MRI scan)

An MRI scan uses a strong magnetic field and radio waves to create pictures on a computer of tissues, organs and other structures inside the body. It can show if there’s a structural cause for your child’s epilepsy.

Functional MRI scan (fMRI scan)

This is similar to the MRI scan but, during the scan, your child will be asked to do something, such as:

  • Tap their thumb against their fingers or do other more difficult finger movements
  • Look at pictures
  • Answer questions on a computer screen

These activities increase the flow of oxygen-rich blood to a particular part of the brain. From these activities it will be possible to see which part of the brain manages important tasks such as thought, speech and language, movement and sensation.

Positron emission tomography (PET scan)

This scan uses a radioactive substance, called a tracer, to look for information about how the brain is working. It can also show if there’s a structural cause for the epilepsy.

Single-photon emission computed tomography (SPECT scan)

This scan shows different parts of the brain in different colours. Your child will be given an injection of a radioactive dye, which will go to their brain. The different colours show how much blood flow is in each part of the brain. Usually, blood flow is highest in the part of the brain where seizures start.

There are 2 sorts of SPECT scans: one is the inter-ictal and the other is the ictal. ‘Inter’ means between and so the inter-ictal SPECT scan is done between seizures. Ictal means seizure, so the ictal SPECT scan is done just after a child has had a seizure.

Magnetoencephalography (MEG scan)

This is a newer type of scan, and is only available in very special circumstances. The scanner sits outside your child’s head and measures their brain activity. It can tell which parts of your child’s brain are active during a certain task.

Neuropsychology tests

These are tests that show if your child has any memory or learning problems. They can take up to 6 or sometimes 8 hours, split into 2 or 3 different sessions, and involve a number of games and puzzles. The results of the tests may help the surgeon in planning the type of surgery your child might need. The results can also show whether the part of the brain that will be operated on is responsible for any functions that other parts of their brain can’t take over. This is to try to make sure your child will not have any problems after surgery that they didn’t have before.

Neuropsychiatry assessment

A psychiatrist with experience of epilepsy brain surgery will see you and your child as part of the initial assessment. As emotional and behaviour problems are common in children with epilepsy, the psychiatrist will check to see if your child has these problems. They will also be able to suggest any treatment your child might need. The treatment will be available, whether or not your child goes on to have surgery. The psychiatrist will also be one of the people who checks with you and your child what your aims and expectations are for surgery.

Other assessments

Other types of assessment might be done, depending on the type of epilepsy, and the type of problems, your child has. These assessments might include some of the following:

  • Speech and language
  • Development
  • Vision, particularly peripheral vision
  • The need for occupational therapy
  • The need for physiotherapy

Invasive EEG telemetry

In a very small number of situations, your child might need to undergo more detailed EEG telemetry. This is called invasive EEG telemetry. This should only be done in a CESS centre, and not locally. The neurosurgeon will do an operation to place the EEG electrodes directly on-to the surface of the brain or into the brain. The electrodes are called ‘strip’ or ‘grid’ or ‘stereo’ electrodes. The reason for invasive EEG telemetry is to find out where exactly your child’s seizures are coming from. Another part of this test is called ‘cortical mapping’. This is to reduce the risk of any post-operative complications if and when the neurosurgeon removes the part of the brain causing the seizures. These complications can include a loss of speech or paralysis down one side of the body. 

If you would like to see this information with references, visit the Advice and Information references section of our website. If you are unable to access the internet, please contact our Epilepsy Action Helpline freephone on 0808 800 5050.



Epilepsy Action wishes to thank Dr Richard Appleton, consultant paediatric neurologist at Alder Hey Children’s Hospital, Liverpool, UK, for his contribution.

Dr Richard Appleton has no conflict of interest.

This information has been produced under the terms of The Information Standard.

  • Updated May 2016
    To be reviewed May 2019

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