A vagus nerve stimulator (VNS) is a device that can help prevent seizures. It has 2 parts, a pulse generator and leads. The pulse generator sits in your chest under your skin. The leads run from the generator to the vagus nerve in your neck.
The VNS is similar to a pacemaker. The pulse generator creates low-energy electrical signals, and the leads carry those signals to the vagus nerve. The pulse generator is programmable though the skin, so you can change the strength, duration, and frequency of the pulses as needed.
The vagus nerve is a long nerve that travels from your brain, through your neck, and into your chest and belly. It has branches that go to your vocal cords, to some of the muscles of your throat, and to other organs inside your body. You have one vagus nerve on the left and one on the right. The ends of the VNS leads wrap around your left vagus nerve.
Most of the vagus nerve fibers carry signals to your brain. Once the signals get to the brain, they travel through both of its sides. A smaller number of vagus nerve fibers carry signals away from the brain.
In addition to helping prevent seizures, a VNS can improve mood. The FDA has approved these devices for recurrent or chronic depression that has not responded to antidepressants.
If you have seizures due to epilepsy, your healthcare provider may recommend medicines to help control your symptoms. If you continue to have seizures even when you take the medicines, or if you have significant side effects, it might make sense to consider other treatment choices. These may include eating a ketogenic diet (a diet high in fat and low in carbohydrates), having brain surgery, or getting a VNS.
There are some reasons why you might need to get a VNS, such as:
- Your medicines do not control your seizures
- You are unable to follow a ketogenic diet
- You continue to have seizures while on a ketogenic diet
- You do not want to have surgery
- You are not a candidate for surgery
- You had surgery, but you still have seizures
Getting a VNS also makes sense for some people who have depression. If you have depression, your healthcare provider may recommend a combination of lifestyle changes, medicines, and therapy. Your healthcare provider may also refer you to a psychiatrist. If you have tried multiple types of treatment choices and still have severe depression, you may benefit from a VNS.
Most people do very well when they get a VNS. However, as with any treatment, getting a VNS does have some risks. Complications due to placement of the VNS are not common, but may include:
- Temporary paralysis of one vocal cord (rare)
The most common complication of a VNS once it is in use is hoarseness. Other, less frequent complications may include:
- Sore throat
- Difficulty swallowing
- Shortness of breath
- Nausea and vomiting
- Worsening sleep apnea in people who already have it
- New sleep apnea in people at risk for it
Most VNS side effects will improve or resolve with adjustment of the VNS settings. If you have sleep apnea, using a continuous positive airway pressure (CPAP) machine while you sleep may help.
There are a few other potential risks related to the device. It may not work properly if one of the leads breaks, if the leads are not in the correct position, or if the pulse generator malfunctions. These are rare complications, however.
Over time, the battery's power will drain. It is important to replace the battery before it loses power.
Placing a VNS is a surgical procedure. Talk to your healthcare provider about what to do to prepare for its placement.
Tell your healthcare provider about all the medicines you take, including over-the-counter medicines like aspirin. Ask whether you should stop taking any of them ahead of time. Let your heathcare provider know if you have any medicine allergies. Also discuss your health history, including if you have had recent problems such as a fever or if you think you might be pregnant.
In some cases, you may need additional tests before your procedure. These might include:
- Monitoring with a video electroencephalogram to characterize and localize seizures
- Chest X-rays and electrocardiogram (ECG), to make sure your lungs and heart are normal
- Blood tests, to make sure you are healthy
You’ll need to avoid food and drink after midnight the night before your procedure. You will also need to arrange to have someone drive you home from the hospital or surgery center.
Your healthcare provider can help explain the details of your surgery. A neurosurgeon, a vascular surgeon, or an otolaryngologist (a healthcare provider specializing in ear, nose, and throat conditions) and a team of other healthcare professionals will place the VNS. You will probably have general anesthesia (numbing medicine), which will make you sleep so that you feel no pain or discomfort during the procedure. You will likely be able to go home the same day.
- You may receive antibiotics to help prevent infection.
- Your healthcare team will carefully monitor your vital signs, like your heart rate and blood pressure, before, during, and after the procedure.
- After cleaning the left side your neck and chest, your surgeon will make a small incision in each spot.
- Your surgeon will move your neck tissues and muscles out of the way to find your left vagus nerve.
- Your surgeon will also create a pocket between the muscles and skin of your chest.
- Your surgeon will create a tunnel, pass the leads through the tunnel, and wrap the ends around your vagus nerve.
- Once the team has attached the leads to the pulse generator, they will test the VNS.
- The surgeon will place the pulse generator in the pocket in your chest and surgically close your skin.
- Your healthcare team will take you from the operating room to the recovery room for further monitoring.
Talk to your healthcare provider about what you can expect after your surgery. Your medical team will continue to watch you closely as you recover. When you wake up, you may have some pain or nausea. If so, medicines can help it go away. You can resume a normal diet as soon as you are able. After you are feeling more awake and doing well, someone can take you home. Your surgeon may give you a prescription for pain medicines.
Keep an eye on your incisions as they heal. You might notice a small amount of drainage from them. This is normal during the first few days. Let your healthcare provider know right away if you have increased redness, swelling, or draining from your incision, high fever, or severe pain.
Make sure to keep all your follow-up appointments so that your healthcare provider can monitor your progress. About 2 weeks after your surgery, your healthcare provider will turn on your VNS. Once your healthcare provider has turned it on, he or she can change its settings during your follow-up visits if needed.
Talk to your healthcare provider about how best to use your VNS. If you have auras before your seizures, you may be able to use a magnet to activate your VNS. This may alter or prevent a seizure from happening. (Auras are symptoms that happen before a seizure.) You should also talk to your healthcare provider about what to avoid once your VNS is in place. For example, you may not be able to have some types of magnetic resonance imaging (MRI) studies or certain heat treatments involving shortwave or microwave. You will continue to need medicines to control your seizures, but if you respond very well to VNS, your healthcare provider may lower your doses or stop some of them. You may notice that your seizure control continues to improve over the next several years. You may also notice improvements in your mood. You may feel more alert and less sleepy during the day
Eventually, you will need to have the battery of your VNS replaced. This can usually be done as an outpatient procedure using the existing leads.Before you agree to the test or the procedure make sure you know:
- The name of the test or procedure
- The reason you are having the test or procedure
- What results to expect and what they mean
- The risks and benefits of the test or procedure
- What the possible side effects or complications are
- When and where you are to have the test or procedure
- Who will do the test or procedure and what that person’s qualifications are
- What would happen if you did not have the test or procedure
- Any alternative tests or procedures to think about
- When and how will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure
January 16, 2018
Vagus nerve stimulation therapy for the treatment of epilepsy. UpToDate
Shelat, Amit, MD,Turley, Ray, BSN, MSN