Vagal Nerve Stimulation

Vagal nerve stimulation (VNS) is the use of pulses of electric currents applied through your vagus nerve to stimulate a portion of your brain. This procedure is used to treat certain medical conditions.

The vagus nerve has 2 branches, which run from your brain stem down each side of your neck and connect with organs and involuntary muscles in your chest and abdomen, such as your stomach, intestines, airways, lungs, and heart. Signals from your brain (efferent signals) travel down your vagus nerves and control swallowing, vocal sounds, coughing, heart rate, intestinal function, and glandular secretion. Signals also travel to your brain (afferent signals) through the vagus nerve and inform your brain how these involuntary muscles and organs are working and if anything needs to be adjusted.

Vagal nerve stimulation was used first to help control seizures in people with epilepsy. It was used for people whose seizures could not be controlled by medication. It was also discovered that VNS seemed to have an affect on the mood of patients, although the reason remains unclear. After several studies, it was approved for use in patients with treatment-resistant depression. Improvement in condition may not be seen until after several months of treatment. Medical studies also are being done to see if VNS might help treat other physical and mental conditions.

WHEN VAGAL NERVE STIMULATION IS USED

The U.S. Food and Drug Administration sets rules on the use of VNS. The rules for use in the treatment of epileptic seizures are as follows:

  • You must be older than 12 years of age.

  • You must have seizures that are not controlled by epilepsy medications.

The rules for use in cases of treatment-resistant depression are as follows:

  • You must be 18 years old or older.

  • You must have treatment-resistant depression that has not responded to 4 or more types of treatment. Treatments may include different types of antidepressant medication and electroconvulsive therapy.

VAGAL NERVE STIMULATION DEVICE

The vagus nerve is stimulated with a device that is implanted in your body. The device is made up of a pulse generator and a lead. The pulse generator, which produces the electric pulse, is about the size of a large watch and is powered by a battery that will last 10 to 12 years. It is placed under the skin of the left upper chest. The lead is a thin wire that connects the generator to your vagus nerve and delivers the electric pulses to your vagus nerve. It is threaded under the skin to the neck and connected to the left vagus nerve.

Placement of the device requires surgery. The operation usually takes 1 to 2 hours and usually takes place on an outpatient basis. Your caregiver will start the pulse generator about 10 days after your surgery. The VNS system will have to be frequently checked by your caregiver to make sure it is working right.

The pulse generator cannot be damaged by cell phones or microwaves. Likewise, airport security systems cannot harm the pulse generator.

HOW THE VAGAL NERVE STIMULATION DEVICE IS USED

The device is activated during a visit to your caregiver a few weeks after surgery. Your caregiver will set the pulse generator to send electronic pulses according to your specific treatment. As therapy for treatment-resistant depression, the pulse generator often is set to give 30-second pulses every 5 minutes. As treatment for epileptic seizures, it often is set to give 30-second pulses every 3 minutes. The duration, frequency, and strength of pulses are usually started low and increased gradually, depending on symptoms and side effects. You can expect periodic follow-up with your provider to ensure that the device is working properly and has not shifted out of position.

You will be given a remote control. This will turn the pulse generator on and off. If the device causes difficulty swallowing during certain activities, such as public speaking, eating, singing, or exercising, it may be necessary to turn the pulse generator off. Only your caregiver will be able to change the duration, frequency, and strength of the electrical pulses. The magnet in the remote control can harm items such as credit cards, cell phones, computer discs, and televisions.

BENEFITS, RISKS, AND SIDE EFFECTS

There are benefits, risks, and side effects associated with the use of VNS stimulation:

  • Benefits include:

  • It is an option when other treatments have not worked.

  • For epilepsy, the number of seizures is cut in half for about half of those who use it.

  • For treatment-resistant depression, results from research indicate that it helps about 1 of every 4 people who use it.

  • Risks are associated with both the surgery to install the stimulation device as well as use of the device. These risks include:

  • Infection.

  • Bleeding.

  • Nerve damage.

  • Scarring.

  • Throat, neck, or chest pain.

  • Numbness or tingling sensation.

  • Side effects include:

  • Hoarseness or voice changes

  • Coughing.

  • Difficulty breathing, especially during exercise.

  • Moments during sleep when your breathing briefly stops (sleep apnea).

  • Headache.

  • Worsening depression and suicidal thoughts. (This is rare.)

  • Pulse generator malfunction or movement requiring additional surgery. (This is rare.)

Side effects associated with use of the device are generally mild and tend to decrease over time. Adjusting the duration, frequency, and strength of the electrical pulses can help minimize side effects. If side effects become intolerable, the device can be shut off temporarily or permanently.