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November 26, 2001

Implanted device effective in controlling epilepsy

By Janet Christenbury


New study results show that an implantable device, called the vagus nerve stimulator (VNS), can help reduce seizure frequency and improve quality of life in children with treatment-resistant epilepsy. The results are published in this month’s edition of the Journal of Child Neurology.

“This is a very promising therapy for children with medically refractory epilepsy,” said Sandra Helmers, associate professor of neurology and principal investigator of the one-year trial.
Epilepsy is a chronic neurological disorder characterized by recurrent, unprovoked seizures. Nearly 2.3 million Americans are affected by the condition, including approximately 422,000 children age 18 and younger. Medically refractory epilepsy is described as a condition that, despite adequate medical therapy, cannot be controlled.

“Through this study, we found that VNS therapy is safe, well tolerated and highly effective in reducing seizure frequency over time in these children,” Helmers said. “Six months after the VNS was implanted, seizures were reduced in the average participant by nearly 45 percent.”

Six centers in the United States enrolled 125 participants in the study, all of whom received the VNS implant. This is the largest group of children to receive the VNS in a study. The participants’ ages ranged from 3 to 18; about a third were younger than 12. The typical participant, aged 12 years, started having seizures at the age of 2 and had already tried nine anti-epileptic drugs before turning to
VNS therapy.

“Uncontrolled seizures can put children at a greater risk of brain damage and increased mortality,” Helmers said. “Evaluating effective seizure-control treatments such as VNS earlier, rather than later, may help children avoid these negative outcomes.”

VNS therapy not only resulted in a decrease in seizure frequency, but also a striking improvement in quality of life. Participants in this study were re-examined at three and six months following implantation; at those times, improvements were reported in alertness, verbal communication, school performance, clustering of seizures and post-seizure periods.

Similar to a cardiac pacemaker, the VNS device is implanted just under the skin in the left chest area. It stimulates the vagus nerve in the neck through pre-programmed, mild, intermittent electrical pulses given 24 hours a day. The implantation procedure takes approximately one hour and usually requires no overnight hospitalization.

The device is manufactured by Cyberonics. In 1997, the Food and Drug Administration (FDA) approved use of the VNS for patients 12 years and older with partial seizures. (Partial seizures affect only one side of the brain.)

Helmers led the six-center study during her tenure at Children’s Hospital in Boston, Harvard Medical School. That hospital, along with University of Texas Medical School in Houston, Minnesota Epilepsy Group, The Children’s Hospital in Denver, Children’s National Medical Center and Louisiana State University Comprehensive Epilepsy Center, were the six centers participating in the trial.


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