Study: Device Prevents Epileptic Seizures, Doesn't Damage Hearts

August 13, 1997

CHAPEL HILL -- Clinical studies show a promising new device for treating intractable epilepsy works well in preventing seizures and has no ill effects on patients' hearts, according to University of North Carolina at Chapel Hill medical scientists.

"About 1.5 percent of the population suffers from epilepsy, and about 25 percent of patients do not respond to medication," said Dr. Bradley Vaughn, assistant professor of neurology at the UNC-CH School of Medicine. "We were part of a multicenter study involving 20 sites around the country that evaluated the implant device in more than 200 patients. We were very pleased with the results because this is going to be a useful tool for treating epilepsy."

About 30 percent of patients studied nationwide had a greater than 50 percent reduction in the number of seizures they suffered, Vaughn said. A few have become free of seizures since the device was implanted, and some who had the same number as before reported their seizures were shorter or less severe.

The battery-operated device, called a vagus nerve stimulator, is about the size and shape of a small compact for women's face powder or a pocket watch, Vaughn said. Surgeons bury it beneath the skin just below the left collarbone, and it is programmed to send electric current every few minutes through a wire that wraps around the vagus nerve in the neck. After extensive clinical trials, the U.S. Food and Drug Administration approved the stimulator July 16. Cyberonics Inc. manufactures it.

By studying the device's effect on the vagus nerve, the UNC-CH team was able to show no changes in patients' heart rates, or cardiac cycles. That revealed no impairment of the body's control of heart rate, which could be dangerous.

The team will present some of its findings next month at an American Clinical Neurophysiology Society meeting in Los Angeles. A report on the research also will appear in an upcoming issue of the journal Seizure, a medical journal specializing in epilepsy.

"This device is neither a cure for epilepsy nor a substitute for medication or epilepsy surgery, but it is useful for otherwise healthy people with no heart or lung problems who have not responded to medication and have frequent seizures," Vaughn said. "It may be applicable to thousands people in the United States."

Possible side effects include slight voice alterations and occasional tight feelings in the throat, Vaughn said. Some patients report a tingling sensation when the device discharges, but most patients stop noticing side effects with time. Battery life is about three years, and no one knows for sure how the device stops seizures.

Drugs most often prescribed for epilepsy include phenytoin, phenobarbital and carbamazepine, said Vaughn, who testified before the FDA panel that recommended approving the stimulator.

Others involved in the research at UNC-CH include Drs. John Messenheimer, Estrada J. Bernard Jr., O'Neill D'Cruz, Albert Hinn and Robert Greenwood.

"To me the most remarkable thing about this type work is that we are venturing into a completely new way of treating epilepsy," Vaughn said. "Always before, we have given medicine and tried to change the environment in the brain around where seizures start by flooding the body with drugs. Now we are trying to change the environment by stimulating nerves upstream toward the brain. This is a very different philosophy of treatment."

Much confusion surrounds how to give first aid safely to a person experiencing epileptic seizure, he said.

"In the majority of cases, you don't need to call 911," Vaughn said. "Turn them on their side, and stay with them until the seizure is over. Only call an ambulance if a seizure is prolonged, if a patient has two seizures without waking up in between them or if the person has hurt himself. You should also call if it was a person's first seizure or if he or she asks to go to the hospital."

"Don't put a spoon or anything else in their mouth," he cautioned. "I knew a man once whose wife had a seizure while they were out fishing. He thought he was supposed to put something in her mouth, but didn't have anything handy. He put his finger in her mouth, and she bit it off."

An X-ray showing the man's finger in his wife's stomach confirmed his story. She was luckier than he was because if the finger had entered her lungs, she could have choked to death.

Note: Vaughn can be reached at (919) 966-3707 or by calling (919) 966-4131 and asking the UNC Hospitals operator to page him at 110-2028.

University of North Carolina at Chapel Hill

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