Title: RFNS: Improves vagus nerve stimulation?
Birdbomb - February 16, 2006 09:30 PM (GMT)
LINK TO ARTICLERFNS: Improves vagus nerve stimulation?
Wed 25 Jan 2006 09:19 AM CST
WASHINGTON DC (myDNA News)
Those suffering from seizures associated with epilepsy will soon be offered a new variation on a standard procedure.
First approved by the U.S. Federal Drug Administration (FDA) in the late 1990s as a treatment for epileptics - estimated at around 1 percent to 2 percent of the American population - vagus nerve stimulation, or VNS, was meant as an alternative to help the approximately 425,000 individuals with the most common type of seizure who couldn't tolerate the side effects of drugs or keep their seizures under control.
VNS targets the vagus nerve, which runs from the stem of the brain to the colon and carries information from the neck, head, abdomen and thorax regarding sensory, motor and autonomic functions in the body.
The VNS device is a pulse generator that is implanted in the chest and has a wire that extends through the left side of the neck and wraps around the nerve. Although the device can be turned on and off as needed, additional surgery to change the battery is usually required every three to eight years.
Research from Baylor College of Medicine in Houston, Texas, suggests that electrical stimulation of the vagus nerve produces "inhibition of neural processes, which can alter brain electrical activity," and, consequently, aid those with epilepsy and treatment-resistant depression.
So, last year, the FDA also approved VNS as an additional treatment for people suffering from depression who don't respond to drug treatment. This can occur up to 50 percent of the time with first-treatment programs.
Studies indicate that VNS can help decrease the occurrence of seizures by 10 percent to 20 percent. While not very many patients become seizure-free, the occurrence of seizures may decrease by 50 percent or more over time.
"While relatively few patients become completely seizure-free, there are some patients who have a dramatic improvement in seizures," said Michael Wong, M.D., an assistant professor in the departments of pediatrics, and neurology, anatomy and neurobiology at Washington University in St. Louis. "Patients may also benefit in other ways by reducing the doses of anti-epileptic drugs, which have side effects, and using the magnet to activate the VNS to potentially abort a seizure after it starts."
With surgery, however, comes the risk of infection. The wire implanted in the neck may cause painful adhesions and restrict movement. And hoarseness, shortness of breath and voice alteration have been reported as side effects of the device, according to researchers.
As a treatment for depression, VNS has also raised red flags. Peter Lurie, M.D., M.P.H., the deputy director of Public Citizen's Health Research Group, said: "The data are simply lacking. If this were a drug, it would never have been approved for depression by such third-rate data."
Researchers at the University of Pittsburgh (UP) believe they may have come up with a solution in eliminating detrimental side effects.
A new radio-frequency neural stimulator (RFNS) device has been developed that makes use of a modified type of deep brain stimulation currently used as a treatment in some people with Parkinson's disease. Rather than implanting a wire attached to the vagus nerve, the RFNS consists of a receiver that's placed under the skin of the neck and a powering device that's placed in a collar or other piece of apparel worn near the implant site. Because the battery is external, as are the wires, the risk of infection from surgery is decreased. The side effects caused by the wire, such as hoarseness, also no longer exist.
Milan Mickle, Ph.D., professor of electrical and computer engineering at UP and leader of the RFNS project said: "This will work, if not identically, then pretty close to how VNS works, except it's a much simpler operation." Bernard - February 16, 2006 11:10 PM (GMT)