VNS therapy involves a small electrical device, like a pacemaker, which is implanted under the skin of your chest. The device sends electrical impulses to your brain through a nerve in your neck called the vagus nerve. The aim is to reduce the number of seizures you have and make them less severe.
How does VNS therapy work?
Image courtesy of LivaNova
VNS therapy uses the VNS system, which is made up of 3 parts:
- A small pacemaker-like device, called a generator
- A thin, flexible wire, called a lead
- A hand-held magnet
The vagus nerve sends messages between the brain and other parts of the body. In VNS therapy, a generator is connected to the vagus nerve by a lead. The generator is programmed to send electrical impulses to the vagus nerve at regular intervals, all day, every day. These impulses are then carried by the vagus nerve to the brain. This regular stimulation can help to reduce the number of seizures you have and make them less severe.
You can also sweep the hand-held magnet over the generator to send more impulses to the vagus nerve. This could be if you have an aura (warning) before a seizure, if you feel a seizure starting, or when you are having a seizure. Some people find that using the magnet stops a seizure happening, shortens the seizure or makes the seizure less severe. A carer, or family member, can also use the magnet, if they see you having a seizure. The magnet can also be used to stop the stimulation for a short time.
Newer models of the VNS generator can also detect increases in heart-rate. In some people with epilepsy an increase in heart-rate can be a sign that they are having a seizure. When the generator detects an increase in heart-rate, it automatically sends more impulses to the vagus nerve. This may help to stop a seizure happening or make it less severe. So with newer models you may not need to use the magnet so much.
Can I have VNS therapy?
The NHS have guidelines about who should or shouldn’t be offered VNS. Only some people with epilepsy are able to have it. It is restricted for adults and children with epilepsy when other treatments have not worked or are not suitable. To be eligible for VNS therapy you must still be having seizures despite trying a number of different epilepsy medicines, or your epilepsy medicine causes you too many side-effects. You must also be unsuitable for epilepsy brain surgery, or you have had brain surgery but are still having seizures.
This is the NHS document describing all the guidance. If you think VNS therapy might help you, you could talk to your epilepsy specialist.
Surgery to implant the VNS system is carried out by a neurosurgeon, usually under general anaesthetic. The operation takes between 1 and 2 hours and you usually go home the same day, or the next day. The neurosurgeon makes 2 small cuts, 1 in a natural crease on the left of your neck, and 1 in the left-hand side of your chest, below your collarbone. The generator is placed under the skin in your chest. A lead is inserted under the skin to connect the generator to the left vagus nerve in the neck.
As with any operation, there is a slight risk of reaction to the anaesthetic. There is also a small risk of bleeding and infection. Your surgeon will give you more information before the operation takes place.
You might have some pain for a while from the area of the implant after VNS surgery. Your doctor can prescribe something for this.
What happens after VNS surgery?
The generator is usually left switched off for two weeks after surgery. This is to help your body heal. After that, it is usually switched on by a specialist nurse in a clinic. They will gradually increase the settings over a number of weeks. This gives you a chance to get used to the stimulation over time.
Will I still need to take epilepsy medicine after the VNS has been fitted?
VNS is designed to be used in addition to epilepsy medicine, not to replace it. Most people need to keep taking epilepsy medicine after they have had a VNS system fitted. Some people are able to reduce the amount of epilepsy medicine they take over time. You will be able to talk to your epilepsy specialist about any possible changes to your medicine.
How long does the generator last?
At some point, the generator will need replacing when the battery runs low. The generator battery can last between 3 and 8 years, depending on the model and settings used. Your doctor or nurse can tell when the battery is running down during your follow up appointments. They will then arrange for a new generator to be fitted. This involves a small operation, which lasts less than an hour.
How do I get a replacement magnet?
If you need a replacement magnet, contact your epilepsy specialist nurse. They should be able to provide you with a new magnet free of charge.
What are the benefits of VNS?
The benefits of VNS can include the following:
- Having fewer seizures
- Having less severe seizures or shorter seizures
- Possibly less epilepsy medicine
- Having improved quality of life
You might find that your seizure control slowly improves over time.
6 out of 10 people who have VNS fitted find that the number of seizures they have is halved.
Between 3 and 6 in a 100 people who have had VNS fitted experienced complications. These were usually related to infection and sorted with a second operation.
Will I get side-effects from VNS?
The most common side-effect reported from VNS is hoarseness/a change in voice. Other common side effects include:
- Sore throat
- Shortness of breath
- Prickling feeling in the skin
Other possible side-effects include palpitations, difficulty swallowing and stomach discomfort. The side-effects of VNS usually happen during stimulation periods, and may improve over time. If you find the side-effects uncomfortable talk to your epilepsy nurse. They may be able to help by altering the level of stimulation. These are becoming less common as the technology improves. Also it is possible to turn the VNS off for a short while using the magnet. If it causes major problems it can be removed.
You can find a list of possible side-effects in the VNS Patient Manual.
If an MRI is recommended for you it’s important that everyone involved in the scan knows about your VNS system. They may need to take precautions to carry out the scan safely. You should have a Patient MRI form from your neurologist to show the people doing the MRI scan. The VNS Therapy website has more information about MRI safety.
Airport security scanners
Airport security scanners should not affect the device or be affected by it. The makers of the VNS therapy system recommend that, to be safe, you should provide the airport security with your VNS Therapy ID card. You can request a pat down check instead.
Other devices to be aware of
Being close to certain types of equipment can affect your generator.
- You will need advice from your doctor about whether it is safe for you to be where there are pacemaker warning signs.This is because the equipment that could affect a pace-maker could also affect your VNS generator
- Stay at least 60 centimetres or 2 feet away from Electronic Article Surveillance System tag deactivators found in shops. This will avoid having your generator activated. The deactivators are mostly found in shop entrances
- Tablet computers and their covers, hair clippers, vibrators and loudspeakers can all have electromagnetic field that you need to keep at least 20 cms or 8 inches away from your chest. If your generator does become activated just move away from the device which is causing the problem
You can find a full list of VNS system precautions in the VNS Patient Manual.
How can I find out more?
You can get more information about VNS therapy from the website of Livanova, who make the VNS therapy system.
Information about children
If you’re thinking about VNS therapy for your child, this site may help them understand more. This includes a video you could watch with your child.
Information with references
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 would like to thank Gnanamurthy Sivakumar, consultant neurosurgeon at Leeds General Infirmary, for reviewing this information.
Gnanamurthy Sivakumar has no conflict of interest to declare.
This information has been produced under the terms of Epilepsy Action's information quality standards.
- Updated August 2019To be reviewed August 2022