Vagus Nerve Stimulation therapy is another form of treatment that may be tried when medications fail to stop seizures. It is currently approved for use in adults and children over the age of 12 who have partial seizures that resist control by other methods. The therapy is designed to prevent seizures by sending regular small pulses of electrical energy to the brain via the vagus nerve, a large nerve in the neck.

The energy is delivered by a flat, round battery, about the size of a silver dollar, which is surgically implanted in the chest wall. Thin wires (electrodes) are threaded under the skin and wound around the vagus nerve in the neck. The battery is programmed by the health team to send a few seconds of electrical energy to the vagus nerve every few minutes. If the person with the system feels a seizure coming on, he or she can activate the discharge by passing a small magnet over the battery. In some people, this has the effect of stopping the seizure. It is also possible to turn the device off by holding the magnet over it.

Side effects of VNS therapy are mostly hoarseness and, sometimes, discomfort in the throat. There may be a change in voice quality during the actual stimulation. Although complete seizure control is seldom achieved, the majority of people who use VNS therapy experience fewer seizures. In some its effectiveness increases with time, and patients report an improved quality of life. As with surgery and the ketogenic diet, it will almost always be necessary to continue anti-epileptic medication although the patient should be able to take less medication than in the past.

Currently, about 32,000 people have received the VNS system.

The VNS system was approved for people with partial onset seizures — seizures that begin in one part of the brain.

It is intended for people whose seizures do not respond to medications and who are either not good candidates for brain surgery or don’t want to have brain surgery.

Also, they must not have any other medical conditions that might be affected by the device. For example, VNS should not be used in people who have had certain other throat operations or disorders affecting the throat.

Currently, about 32,000 people have received the VNS system. A registry system that tracks about 5,000 people living with VNS includes about 60 percent with partial seizures; 15 percent with the Lennox-Gastaut syndrome (mixed seizures); and 25 percent with generalized seizures.

Implanting the VNS battery in a patient and connecting it to the vagus nerve takes about an hour. It is usually done under general anesthesia, though local anesthesia is sometimes used. The operation can be done on an in-patient or out-patient basis.

The surgeon makes two small incisions — one in the neck to gain access to the vagus nerve, and one below the collarbone in the chest wall or armpit.

The surgeon places the VNS pulse generator into a surgically-made “pocket” under the skin of the patient’s chest and threads a plastic tube containing the electrodes from the neck to the generator in the chest. He or she then gently wraps the flexible ends of silicone-coated electrodes around the vagus nerve.

Programming the Device

Some doctors turn on the VNS device immediately after surgery. Others prefer to start the stimulation during the check up visit afterwards. Doctors program the device to deliver pulses of electrical stimulation automatically, 24 hours a day.

A typical “dose” is about 30 seconds on and five minutes off, but settings may vary. The device continues the cycle until the neurologist re-programs it or until the battery runs out — usually in about six years.

At that time another surgical procedure (which only involves the chest) can be done to replace the battery, usually with a local anesthetic.

It’s hard to know in advance how someone with epilepsy will respond to VNS therapy.

Successful VNS therapy reduces the number of seizures people have and, sometimes, how long they last. It’s unlikely to stop seizures completely.

Studies show that about one-third of people treated with VNS experience a major improvement in seizure control. One-third experience some improvement, and one-third continue to have seizures as before.

Even when people respond well, improvement usually takes time. It isn’t likely to happen immediately after the doctor implants the device. Several months may go by before there’s any change, followed by a slow but steady improvement.

However, seizure control is not the whole story for this type of treatment. For reasons that are still not well understood, VNS therapy appears to have some other effects as well.

Studies find that many people who have had the implant say they feel better, even if their seizures continue. They say they feel better after a seizure, are in a better mood, feel more alert, have better memory and fewer emergency room visits.