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