Vagal nerve stimulator how does it work

Surgical complications with vagal nerve stimulation implant are rare and are similar to the dangers of having other types of surgery. They include:. Vagal nerve stimulation is considered safe.

Mild side effects occur in some people when the device stimulates the nerve, which is approximately 30 seconds. The most common side effects include:.

For most people, the side effects are tolerable. They may lessen over time, but some side effects may be bothersome for as long as you use vagal nerve stimulation. Adjusting the electrical impulses can help minimize these effects. After the vagal nerve stimulator is implanted, the battery powered device can be programmed from outside your body by your doctor. It will be programmed to deliver electrical impulses to the vagus nerve at various durations, frequencies and currents.

You can also use a handheld magnet to turn the device on if you feel a seizure about to start, and turn it off if it is causing unpleasant side effects. It may also shorten a seizure already in progress.

It is usually performed on an outpatient basis. As with all surgeries, there is a small risk of infection. Other surgical risks of VNS include inflammation or pain at the incision site, damage to nearby nerves and nerve constriction. The procedure requires two small incisions. The first one is made on the upper left side of the chest where the pulse generator is implanted Pulse Generator, Figure 1. A second incision is made horizontally on the left side of the lower neck, along a crease of skin.

This is where the thin, flexible wires that connect the pulse generator to the vagus nerve are inserted Lead, Figure 2. The device or implant is a flat, round piece of metal that measures about an inch and a half 4 centimeters across and mm thick, depending on the model used Pulse Generator, Figure 1. Newer models may be somewhat smaller. The stimulator contains a battery, which can last from one to 15 years.

When the battery is low, the stimulator is replaced with a less invasive procedure which requires only opening the chest wall incision. The stimulator is most commonly activated two to four weeks after implantation, although in some cases it may be activated in the operating room at the time of implantation. The treating neurologist programs the stimulator in his or her office with a small hand-held computer, programming software and a programming wand Programming Wand, Figure 3. The strength and duration of the electrical impulses are programmed.

The amount of stimulation varies by case but is usually initiated at a low level and slowly increased to a suitable level for the individual. The pulse generator is about the size of a stopwatch and runs on battery power. A lead wire is connected to the pulse generator. The lead wire is guided under your skin from your chest up to your neck, where it's attached to the left vagus nerve through the second incision. Surgeons implant a device near the collarbone and run a wire to the vagus nerve.

When the device fires it stimulates that nerve to send signals to the brain. This increases activity in areas that control mood. The pulse generator is turned on during a visit to your doctor's office a few weeks after surgery. Then it can be programmed to deliver electrical impulses to the vagus nerve at various durations, frequencies and currents. Vagus nerve stimulation usually starts at a low level and is gradually increased, depending on your symptoms and side effects.

Stimulation is programmed to turn on and off in specific cycles — such as 30 seconds on, five minutes off. You may have some tingling sensations or slight pain in your neck and temporary hoarseness when the nerve stimulation is on. The stimulator doesn't detect seizure activity or depression symptoms. When it's turned on, the stimulator turns on and off at the intervals selected by your doctor. You can use a hand-held magnet to initiate stimulation at a different time, for example, if you sense an impending seizure.

The magnet can also be used to temporarily turn off the vagus nerve stimulation, which may be necessary when you do certain activities such as public speaking, singing or exercising, or when you're eating if you have swallowing problems.

You'll need to visit your doctor periodically to make sure that the pulse generator is working correctly and that it hasn't shifted out of position. Check with your doctor before having any medical tests, such as magnetic resonance imaging MRI , which might interfere with your device. Implanted vagus nerve stimulation isn't a cure for epilepsy. Most people with epilepsy won't stop having seizures or taking epilepsy medication altogether after the procedure.

But many will have fewer seizures, up to 20 to 50 percent fewer. Seizure intensity may lessen as well. It can take months or even a year or longer of stimulation before you notice any significant reduction in seizures.

Vagus nerve stimulation may also shorten the recovery time after a seizure. People who've had vagus nerve stimulation to treat epilepsy may also experience improvements in mood and quality of life. Research is still mixed on the benefits of implanted vagus nerve stimulation for the treatment of depression. Some studies suggest the benefits of vagus nerve stimulation for depression accrue over time, and it may take at least several months of treatment before you notice any improvements in your depression symptoms.

Implanted vagus nerve stimulation doesn't work for everybody, and it isn't intended to replace traditional treatments. Studies of implanted vagus nerve stimulation as a treatment for conditions such as Alzheimer's disease, headaches and rheumatoid arthritis have been too small to draw any definitive conclusions about how well it may work for those problems.

Because of the size of the stimulator there will be a small lump where it lies, and a small scar where it was put in. A lead connects the stimulator in the chest to the vagus nerve in the left side of the neck. Because the electrodes are coiled around the nerve in the neck, there will also be a small scar where they are inserted, usually in the fold of the neck. The stimulator is usually switched on within four weeks of it being implanted.

The neurologist or nurse will programme the stimulator and set the amount strength and length of the electrical stimulation given. The amount of stimulation varies from person to person, but is usually started at a low level and slowly increased to a suitable level for each person. Usually it is set at 30 seconds of stimulation every five minutes through the day and night. The stimulator has a battery inside it which can last up to ten years. When the battery is low, the stimulator needs to be replaced, during an operation similar to the one when it was put in.

Some people have a warning or aura which is a focal aware seizure that tells them that they are going to have a further seizure. When this happens, a special magnet can be passed over the stimulator to give stronger stimulation for a slightly longer period of time. This may stop the aura from developing into another seizure, or may reduce how long it takes the person to recover after a seizure.

Keep the magnet close by - it can be worn on the wrist like a watch, or on a belt, or attached to a wheelchair. For people who have no warning before a seizure, someone else could use the magnet for them when a seizure happens. Some people may experience an increase in heart rate during their seizures. VNS therapy can cause side effects but usually only during the time that the nerve is being stimulated.

Side effects may not happen for everyone but can include discomfort in the throat, a cough, difficulty swallowing, and a hoarse voice.

Side effects may reduce over time and do not usually mean that the stimulator has to be switched off. If side effects are a problem, the neurologist or nurse can adjust the settings, or the magnet can be held over the stimulator for a few seconds to briefly stop the stimulation.