Vagus Nerve Stimulation Proves to be
an Effective Treatment in Children with Difficult-to-Treat Epilepsy
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," according to Sandra Helmers, M.D., associate professor of
neurology, Emory University School of Medicine and principal investigator
of the one-year trial. 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," Dr. Helmers reports. "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 received the vagus nerve stimulator implant. This is the largest
group of children to receive the VNS in a study. The age of participants
ranged from three to 18. About one-third of the participants were younger
than 12 years of age. The typical participant, aged 12 years, started
having seizures at the age of two 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,"
Dr. Helmers explains. "Evaluating effective seizure control treatments
such as VNS earlier, rather than later, may help children avoid these
Treatment with VNS therapy not only resulted in a decrease in seizure
frequency, but also in a striking improvement in various aspects of
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.
The vagus nerve stimulator, similar to a cardiac pacemaker, is implanted
just under the skin in the left chest area. It stimulates the left vagus
nerve in the neck through pre-programmed, mild, intermittent electrical
pulses 24 hours a day. The implantation procedure takes approximately
one hour and usually requires no overnight hospitalization. The device
is manufactured by Cyberonics out of Houston, Texas. In 1997, the Food
and Drug Administration (FDA) approved use of the VNS for patients,
12 years of age and older, with partial seizures. Partial seizures only
affect one side of the brain.
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 aged 18 years and
Dr. Helmers lead the six-center study, funded by Cyberonics, 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 this trial. Dr.
Helmers now works in the Department of Neurology at Emory University
School of Medicine, specializing in epileptic treatments in children