Vagus Nerve Stimulation: When Medications don’t Control Seizures
Vagus nerve stimulation, or VNS, is one of the latest epilepsy treatment techniques. It’s been available since 1997. The vagus nerve is part of the nervous system that affects body functions that we can’t control. This nerve goes from the brain stem through the neck and into the chest and abdomen. Stimulating the vagus nerve can decrease seizure activity in some people, although nobody knows for sure exactly how or why it works.
Candidates for VNS are people with “defined” epilepsy (those who have been diagnosed with actual epilepsy, not just seizures) that’s sufficiently severe. Additionally, candidates are not able to control their seizures with medication.
During the VNS procedure, a stimulator that looks very much like a pacemaker is implanted in the patient’s chest. “A wire from the stimulator wraps around the vagus nerve in the neck and stimulates it every 5 minutes,” explains Dr. Mark Bej, a neurologist in private practice in northern Ohio.
There are some effects of the stimulator that the patient can feel. “There can be some hoarseness during stimulation, because it affects the voice box, and there may be some coughing during stimulation, but for most people, these side effects are mild,” says Dr. Bej. “And you can manually control the stimulator with a magnet. For people who can tell when a seizure is coming on, they can sweep the magnet across the chest where the stimulator is. This turns the stimulator on, and can often stop or decrease the severity of the seizure. People who might want to turn the stimulator off for a brief period of time, say if they’re about to give a speech, can tape the magnet on their chest and the stimulator goes off.”
Results of the VNS technique vary widely. Dr. Bej says, “I have one patient who was on two medications but she was having one or two seizures per month. She had the VNS procedure, her seizures went to zero, and I was eventually able to take her off one of her medications. So now she’s on one drug plus the stimulator, and it’s been like this for her for several years.”
At the other extreme, “Some people have the stimulator placed and they have absolutely no change.
But for people who do respond, VNS is very helpful. “Putting people on the stimulator is about as effective as adding an additional medication. This can be helpful because epilepsy medication can cause side effects like drowsiness or dizziness, and the VNS doesn’t have those types of symptoms,” Dr. Bej says.
According to Dr. Bej, “For now, the stimulator is used only for people who can’t control their seizures on their current medication. In a few years, we might see a clinical trial to determine whether people who do control their seizures with medication are good candidates for the stimulator.”
The procedure is performed under general anesthesia. Patients typically go home that day with pain medication, and they’re usually back at work in a few days.
O. Devinsky. Epilepsy Patient & Family Guide. F.A. Davis Company, Philadelphia, Pennsylvania, 2002; Dr. Mark Bej, Northern Ohio Neurologist.