Q & A Chat on Vagus Nerve Stimulation: What's it all about?

On March 24, 2008 Dr.Steven Schachter was our guest expert to answer questions about VNS Therapy or vagus nerve stimulation. The answers provided by Dr. Schachter and the content on epilepsy.com are intended for general educational purposes. People should direct specific questions about their situation to their treating doctor.

We are pleased to welcome Dr. Steven Schachter, Professor of Neurology at Harvard Medical School and an epileptologist at Beth Israel Deaconess Medical Center. He is Editor in Chief of the scientific journal, Epilepsy & Behavior and the Editor in Chief of epilepsy.com.

Question: When is VNS considered and how does it work?
Answer – Dr. Schachter: VNS should be talked about with the doctor if the first two or three medications tried do not stop seizures, and the medications were taken as prescribed.

VNS provides electrical stimulation to a nerve in the neck, called the vagus nerve, which in turn sends the signals up to the brain. This is effective at reducing seizures in many people with epilepsy.

For more information:

Question: Can the VNS work for people with partial seizures?
Answer- Dr. Schachter: Yes - in fact VNS is approved by the Food and Drug Administration (FDA) for partial seizures. Details of the clinical research involving persons with partial seizures can be found at www.epilepsy.com/epilepsy/vns.

VNS has been shown to work for partial seizures. There is some evidence that VNS may work for other seizure types, but this evidence is not as strong as for partial seizures.

VNS stands for Vagus Nerve Stimulation. This is an electrical form of therapy that was approved by the FDA for partial seizures in 1997. In fact, it's the only form of non-drug therapy approved by the FDA for the treatment of epilepsy. The treatment involves a surgical operation to implant a battery in the left upper chest and to connect the battery via a wire to the vagus nerve in the left side of the neck. The battery is controlled by the doctor or nurse and sends intermittent electrical signals to the vagus nerve by the wire that connects it to the battery.

Question: Can VNS be used for generalized forms of epilepsy?
Answer - Dr. Schachter: VNS is not approved by the FDA for generalized seizures. There is some evidence in the medical literature that VNS might be effective for some patients with generalized seizures. Your doctor can evaluate that evidence and your situation to see if he or she would recommend VNS for you.

Question: What is the length of time that a person should wait before considering a vagus nerve stimulator?
Answer - Dr. Schachter: There's no particular length of time but rather enough time to show that at least two different seizure medicines, taken consistently at appropriate doses and which are appropriate for a person's type of seizures, are not adequate to control seizures satisfactorily. This determination is best made between each individual patient and their doctor. Under these circumstances, VNS should be discussed along with other options, such as other seizure medicines, the possibility of epilepsy surgery, a special diet, investigational medicines or devices, or lifestyle modifications.

Question: Is surgery to place a VNS risky?
Answer – Dr. Schachter: The surgery for VNS involves two incisions - one in the left upper chest and the other along the left side of the neck. There is a small risk of infection and trauma to other nerves in the neck. There are other possible side effects that occur very infrequently.
Epi_help: Before having a VNS implanted, people should read the Patient Manual provided by Cyberonics and have a thorough discussion of potential risks from surgery as compared to side effects that may be associated with programming of the device. The programming side effects are usually temporary and can be lessened or eliminated by adjusting program parameters, or the dose of stimulation that is delivered to the vagus nerve and brain. People should also be aware of practical safety issues with use of any implanted device and the use of a magnet that may affect daily activities or traveling. Before any medical procedures or tests are done, people with an implanted device should talk to their VNS team. For example, MRIs of the head may be done but only with a special MR machine that uses a transmit and receive head coil. The VNS device is also turned off before the MRI is done to lessen the change of any side effects. Body MRIs are not recommended nor are other procedures that may cause excessive heating of the coils around the vagus nerve or that can interfere with the electronic stimulation. For a full review of safety issues, people are encouraged to view the Cyberonics Patient Manual found at www.vnstherapy.com

For more information:

Question: If someone had partial seizures originating in only one temporal lobe, is there ever a time when having a VNS would be better treatment than having a lobectomy?
Answer - Dr. Schachter: That's a good question, and one that is difficult to answer without knowing all the details. The answer depends on which side of the brain is involved, whether there is any evidence of damage to the temporal lobe that causes the seizures, which part of the temporal lobe is involved, and how you feel about brain surgery and the possible risks of both types of operations. For some patients, brain surgery has an excellent chance of eliminating seizures - for those patients, if they are willing to have brain surgery, the chances of a good outcome are much higher than they would be with VNS.

Question: When the VNS is adjusted, is a person free to go anywhere they want? How often is a visit to the doctor needed? Could a vagus nerve stimulator be implanted abroard and then return to their own country?
Answer – Dr. Schachter: It is important to have access to someone for programming the VNS, though this is not usually necessary after the first few months.
Epi_help: Once the right dose or level of vagus nerve stimulation is reached, a person may still need to see a person periodically who can test the device to make sure it is working properly. Also, many times the level of stimulation is adjusted to improve seizure control or limit side effects over time.

Question: Is there any ‘best hospital’ to go to for help with epilepsy?
Answer – Dr. Schachter: While any neurologist can diagnose and treat seizures, there are also many hospitals and doctors who specialize in treating epilepsy.

Question: What can you tell us about NeuroPace and the responsive neurostimulator?
Answer – Dr. Schachter: NeuroPace makes and is currently testing an electrical stimulation device that is implanted inside the skull. It senses the beginning of a seizure and then delivers an electrical impulse. A clinical study is currently underway and we won't have results for some months.

For more information:

Question: Is there any type of epilepsy that vagus nerve stimulation does not help?
Answer - Dr. Schachter: It's only been definitely shown to help partial seizures. It has not been definitively shown to help or not to help other seizure types.

Question: What are the chances that VNS may be successful and would the results be seen right away, or do people need to wait a while before seeing changes?
Answer – Dr. Schachter: Overall, about 1 in 3 people have a reduction in the number of their seizures, another 1 in 3 have a reduction in the severity of their seizures, and 1 in 3 may not have any change. The after effects of seizures, called the postictal state, may be shorter. It may take weeks to months for an effect to be seen. This is unlike medications, which usually start to work much quicker.

Question: When you refer to ‘other seizures’, do you mean grand mal seizures?
Answer - Dr. Schachter: The overall statistics I have used refer to partial seizures.

Question: In comparison to the past five years, do you estimate that the number of VNS procedures will increase or decrease over the next five years in the USA?
Answer - Dr. Schachter: Good question! Let’s regroup in 2013.

Question: Do you mean will seizures go away completely with VNS therapy?
Answer – Dr. Schachter: It is possible for seizures to stop entirely for someone who has VNS, but this is unusual - perhaps in 1 in 20 people or less. This is possibly because people who tend to be referred for VNS often have very frequent and very difficult-to-control seizures.

Question: What are the most common side effects that a person may have with VNS?
Answer - Dr. Schachter: Other than the side effects of the surgery and incisions, the most common side effects are related to the times that the stimulation is being delivered or is ‘on’. These include hoarseness, sore throat, a tingling sensation in the face and neck, or discomfort. These side effects usually go away in time, and can be reduced by programming the battery.

Question: How often does infection occur from the surgery?
Answer – Dr. Schachter: It's unusual, but I don't know the overall figure. Check the links at the end of this chat.

Question: If a seizure comes on, can VNS help prevent it?
Answer – Dr. Schachter: For some people, use of the magnet to trigger an extra burst of stimulation when a seizure is beginning might stop or reduce the seizure. The magnet is given to the patient after the VNS is implanted. How often this happens to prevent a seizure isn’t clear.

For more information:

Question: Does VNS affect a person's mood? I hear that it is being used to treat depression too. Can you comment on this?
Answer - Dr. Schachter: VNS is approved by the FDA for treatment-resistant depression.

Question: Can people come off their medicines once VNS is put in?
Answer - Dr. Schachter: For the vast majority of people, seizure meds are continued after the VNS is implanted. For the small number of people whose seizures become much improved from VNS, it might be possible to reduce or stop one or more seizure meds without loss of seizure control, but this needs to be discussed thoroughly with the doctor. There is no way to know in advance whether seizures might worsen once medicines are reduced or stopped.

Question: Is VNS considered a treatment of last resort?
Answer – Dr. Schachter: Not necessarily, and should be considered along with the other options I mentioned earlier when the first 2 or 3 medications are not working to stop seizures. The risks and benefits should be compared to the other options.

Question: How long should a person wait to see if the VNS will work?
Answer – Dr. Schachter: I would recommend waiting at least a year. Some of my colleagues recommend waiting 18 months. If after that time there does not seem to have been any benefit, then the VNS can be turned off. If seizures worsen, then it was helping and can be turned back on. If seizures don't worsen, then whether to remove the battery and the wire should be discussed with the doctor.

Question: What are the cost comparisons between VNS surgery and a temporal lobectomy?
Answer – Dr. Schachter: Not sure. There are costs to the insurance company, and costs to the patient or family. There are also costs to ongoing seizures. All of these need to be considered along with the risks and benefits.

Question: What is RNS which was mentioned earlier?
Answer – Dr. Schachter: RNS stands for Responsive NeuroStimulation. This is the NeuroPace device that is currently being tested.

For more information:

Question: Do people ever get VNS put in after they have had surgery?
Answer – Dr. Schachter: Yes - and it can go the other direction too.

Summary: I’d like to thank everyone for their time and excellent questions. Thank you also to Dr. Schachter for his expertise and time. This chat covered a range of issues about vagus nerve stimulation that I hope will be helpful to our readers. For additional information about VNS, please see the following links:

Edited by Steven C. Schachter, MD

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