Epilepsy: navigated transcranial magnetic stimulation (nTMS)

Information about navigated transcranial magnetic stimulation (nTMS) and how it can be used in people with epilepsy.

It explains how nTMS works, how it is used to help plan treatment, and who it may be suitable for. It also describes what to expect when you come to GOSH for assessment.

When you have epilepsy, your brain waves can get mixed up, which causes fits or seizures. Sometimes these seizures start in one bit of the brain.

nTMS is a non-invasive procedure that uses short magnetic pulses to work out which areas of the brain control movement and language. nTMS can help doctors to see if these parts of the brain are near to where the seizures start.

This is helpful when working out whether surgery might be a suitable and safe option to help treat your epilepsy. It helps make sure that any potential surgery will minimise damage to the areas of the brain that control the body’s movement and language.

You will sit in our special nTMS chair*. This can be adjusted so you’re comfortable. We will give you earplugs to put in as the test makes a loud clicking noise.

We will stick several small special stickers called electrodes to your arms and legs. These will be used to work out which part of your brain controls movement. We will also put a small plastic sticker on to your forehead. This is to track the position of your head relative to the coil which delivers the magnetic pulse.

This coil is held over the top of your head.  We will only touch your head to steady the coil to make sure the pulse is delivered to the right spot.

We will then deliver short magnetic pulses through the coil, which travel through the skin and skull to the brain. This does not hurt, but you might feel some tingling in your face. Your hands and legs might move in response to the pulses. The stickers on your arms and legs will pick up this movement.

The pulses are mapped onto your latest MRI scan. This allows us to see the area of the brain we have stimulated as a ‘hot spot’.

We may then ask you to do some tasks such as naming simple pictures while the pulses are being delivered. This is to work out which areas of the brain control speech.

Once the test is completed, the doctor will remove the electrodes and head-tracker. You can then go home if you have no other tests planned.

*If you are a parent or carer of a baby or smaller child, you can sit in the chair and hold them during this procedure. We can also give you earplugs.

The whole test will take around one to two hours. Please feel free to bring toys, books, or your favourite comforter, as well as any snacks or drinks.

The main benefit of nTMS is that it is non-invasive. However, it is not suitable for everyone.

nTMS sends a magnetic pulse, so it may not be safe for people with certain types of metalwork in their head or neck, such as surgical clips or orthodontic braces. Dental fillings and implants are usually okay. It is also not suitable for anyone with a pacemaker or cochlear implants.

Before each session, we will ask some ‘metal check’ questions – these are similar to the checks done before an MRI scan. These checks only apply to the person having nTMS, as the range of the magnetic pulses is very small.

You will have to sit quietly for short periods but will be able to move around between pulses. If you are worried that you might not be able to sit still enough, please discuss this when we call to arrange the appointment.

The clinical team will meet at the Epilepsy Surgery Meeting to discuss all the information we have about your epilepsy and to see what else we need to find out to get as full a picture as possible. If the team feel that nTMS would be helpful, they will contact you to explain more about the procedure and offer you an appointment.

As you have epilepsy, there is a possibility that the pulse could trigger a seizure.  You can discuss this with the clinical team when they contact you and again when you come for the appointment.

nTMS is widely used for several medical conditions. It is low-risk and side effects are uncommon. It can cause a tingling feeling where the pulse is delivered, along with light-headedness and muscle contraction. Headaches and tinnitus (ringing in the ears) have also been commonly reported. We give you earplugs to reduce any effects of the noise of the nTMS device. These side effects are usually temporary.

A functional magnetic resonance imaging (fMRI) scan is an alternative to nTMS.

Whereas a normal MRI scan gives still pictures of the structure of the brain, an fMRI scan shows which parts of the brain are activated when certain tasks are carried out, such as movement or talking.

The information gained from this test is not exactly the same as from nTMS however, so both tests may be needed.

Take all your medications, including anti-epileptic medicines, as normal.

Please come to the Clinical Neurophysiology (EEG) Department at the time stated on your appointment letter. If you are running late, please call us on 020 7813 8471.

The person bringing you to your appointment should have ‘Parental Responsibility’ for you.

Parental Responsibility refers to the individual who has legal rights, responsibilities, duties, power, and authority to make decisions for a child. This is because the person may need to give consent for you to have the test. If the person with Parental Responsibility is unable to attend, we will still need them to give consent – we might need to telephone them during the test.

The Neurophysiology consultants will review the results of the nTMS. Once they have been reviewed, the results will be added to the information from other tests and shared with the wider Neurology Team.

This will help them to plan whether surgery would be suitable and safe, reducing your seizure activity while maintaining as much function as possible.

They will discuss the outcomes of all the assessments at your next appointment.

If you require more information about the test or have any questions, please call the Department of Clinical Neurophysiology on 020 7813 8471. We are open Monday to Friday, 9am to 5pm.

If you are unable to make your appointment, please call us as soon as possible as we may be able to offer the appointment to another child on the waiting list.

• The NCYPE - National Centre for Young People with Epilepsy – can offer support and advice to young people on all aspects of living with epilepsy.
• Epilepsy Action also offers support and advice to anyone affected by epilepsy.