Vagal Nerve Stimulation

The vagus nerve, which lies in the neck, serves as one of the many highways of information carrying messages to and from the brain and it has many connections to areas in the brain instrumental in producing seizures. Research suggests that stimulation, or electrical activation, of the vagus nerve can disrupt the abnormal brain activity responsible for seizures. Treatment with an implantable vagus nerve stimulator may help reduce the frequency or severity of seizures in some patients.

Assessment
To determine if treatment involving the vagus nerve is appropriate, physicians will conduct a thorough physical history, as well as diagnostic tests such as encephalograms (EEGs), magnetic resonance imaging (MRI), and positron emission tomography (PET). The treatment may be recommended for patients who no longer respond well to medication and are not likely to respond to surgery.

Treatment
Vagus nerve stimulation involves the implantation of a small pacemaker-like device under the skin of the upper left chest. The implant is connected to a wire that leads to a delicate coil that attaches to the vagus nerve in the left side of the neck. Periodically, usually for 30 seconds every 5 minutes, the implant stimulates the vagus nerve with a gentle electrical current. Although the mechanism by which vagal nerve stimulation works is not entirely clear, it appears to decrease the frequency and severity of seizures in some patients.

While the procedure to implant the stimulator takes only two hours, the effects of vagal nerve stimulation may take up to three months to appear. The stimulator will be programmed in the office in the days after surgery and it can be reprogrammed if necessary. Vagal nerve stimulation does not provide a cure, and many patients may still have to take antieplileptic medication after the procedure. It may, however, reduce the amount of medication necessary or make the medication work better.

Guidelines for ideal stimulation frequency and level are under development. While most of the initial research was conducted with patients with partial (focal) seizures, it also may be useful for patients with generalized seizures.