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Return to Vagus Nerve Stimulation Calms Epilepsy Overview

More on Vagus Nerve Stimulation Calms Epilepsy

Vagus Nerve Stimulation Calms Epilepsy

Device functions as "pacemaker for the brain." Calms epilepsy but not "miracle cure" - patients still need medication.

New York (Jun 28, 2010)

Illustration of human head with gears to represent brain working

According to the World Health Organization, epilepsy affects approximately 50 million people worldwide, with 2.4 million new cases diagnosed each year. The condition, generally attributed to people who have had two or more unexplained seizures, is typically chronic and lifelong.

Medication First Line of Treatment

Medication, which has proven successful for about two-thirds of epilepsy patients, continues to be the primary treatment. "The newer epilepsy drugs developed over the last decade or so are more targeted and less harsh than some of the older drugs like phenobarbitol," says Douglas R. Labar, M.D., Ph.D., Director of the Division of Clinical Neurophysiology at NewYork-Presbyterian Hospital/Weill Cornell Medical Center. "But as effective as the new drugs can be, they still often come with side effects that range from annoying to debilitating. Those can include drowsiness, dizziness, memory problems, and poor concentration, or even rare and specific ailments like anemia, sodium deficiency, allergies and kidney stones."

For patients who experience side effects with medication, for those whom medication is ineffective, or for those with non-localized seizures where doctors are unable to locate the seizure source in the brain and remove it, an electrical device known as the Vagus Nerve Stimulator (VNS) may be an appropriate treatment option.

History of VNS

As early as the 1950s, epilepsy researchers noticed that stimulating the vagus nerve, located in the neck and stretching from the brain stem down to the abdomen, changed a person's brain wave pattern. Those early researchers theorized that if they could alter function and change patterns, they might be able to control seizures. Animal testing eventually led to clinical trials, which were conducted at NewYork-Presbyterian in the mid-1990s. The device known as the Vagus Nerve Stimulator was approved by the FDA in 1997.

Douglas R. Labar, M.D., Ph.D.
Douglas R. Labar, M.D.,
Ph.D.

Sometimes called "a pacemaker for the brain," the device itself is flat and round, slightly larger than a quarter, and implanted under the skin, near the armpit. A wire from the device is run (under the skin) over the shoulder, and wound around the vagus nerve in the neck. The device is programmed to deliver an electronic pulse, in continuous cycles, typically 30 seconds on followed by five minutes off, at a predetermined pulse strength. The settings – both timing and pulse strength – can be adjusted without surgery, by using a wand connected to a computer.

Not "Miracle Cure" But Improved Results Over Time

"VNS is not a miracle cure, but it sure beats repeated experimentation with drug combinations," says Dr. Labar, who was involved in the initial clinical trials about 13 years ago when the device was being tested. In fact, VNS reduces the seizure rate by more than 45-50%, even in people with refractory epilepsy (epilepsy not responsive to medication).

Steven Karceski, M.D., an Associate Attending Neurologist at The Neurological Institute of NewYork-Presbyterian Hospital/Columbia University Medical Center, echoes the sentiments of Dr. Labar. "By now, I have met 200 - 300 people who are using the device. In my experience, the longer a person uses the VNS, the better it seems to work. Many of my patients are receptive to VNS because their medicines are not working, or are causing side effects, and they are looking for something else," he says.

Steven Karceski, M.D.
Steven Karceski, M.D.

It is important to note that VNS is not without its own side effects. Although it has no medical effects or drug interactions, it stimulates a nerve that goes to the voice box, often causing a deepening of the voice that lasts several seconds, and occurs with each stimulation. For most people, this side effect goes away, or diminishes over time. Nor does VNS treatment mean an end to medication, although the number of drugs as well as the dosage can usually be significantly reduced. The battery that powers the device also needs to be replaced every five to ten years, requiring surgery each time.

The Future

Over the years it has been in use, VNS hasn't changed dramatically, but has undergone incremental improvements. The device has become smaller and the low battery indicator functions have improved. Special magnets can now be waved (by the patient or a bystander) near the device that cause the stimulator to become more active between intervals, often averting an oncoming seizure or reducing its severity in patients who have pre-seizure warnings, known as auras. Says Dr. Labar, "We're learning that the longer the device is in place, the better it seems to work."

The future seems to lie with using VNS for applications beyond epilepsy. Up to 50% of people with refractory epilepsy also suffer from depression and/or migraine headaches. Dr. Labar, along with other researchers in Germany, has conducted clinical trials and found VNS to be somewhat successful at treating such patients.

Researchers are also designing devices that treat epilepsy with direct stimulation to the brain rather than through the vagus nerve. One machine, a continuous thalamic (or deep brain) stimulator, is in the final stages of FDA review. Another, a responsive nerve stimulator that works closer to the skull, is in development and has the added advantage of recording brain activity, which will provide researchers with potentially important data. Neither of these stimulators would replace VNS, but would provide additional methods of seizure reduction.

"As a doctor, I'm always aiming for seizure-freedom. The VNS does this about 5% of the time," says Dr. Karceski. "But as with any research, one idea leads to another. I think that VNS is the first step on a journey that hopefully will end with a treatment that stops seizures and prevents epilepsy."

Related Video

Dr. Labar discusses surgical treatments for epilepsy, including VNS, on NewYork-Presbyterian's YouTube channel.

Contributing faculty for this article:

Douglas R. Labar, M.D., Ph.D., is the Director of the Division of Clinical Neurophysiology at NewYork-Presbyterian Hospital/Weill Cornell Medical Center and a Professor of Neurology and Neuroscience at Weill Cornell Medical College.

Steven Karceski, M.D., is an Associate Attending Neurologist at The Neurological Institute of NewYork-Presbyterian Hospital/Columbia University Medical Center and an Associate Clinical Professor of Neurology at Columbia University College of Physicians and Surgeons.

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