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.
Who Uses VNS
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.