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NEW TECHNIQUE HELPS CONTROL EPILEPSY IN CHILDREN WHO HAVE FAILED ALL OTHER TREATMENTS
SAN ANTONIO (Sept. 25, 2000) -- A technique which has shown some promise in controlling epileptic seizures in adults may be even more successful in children, according to research presented here today during the 50th Annual Meeting of the Congress of Neurological Surgeons (CNS). This technique, called vagal nerve stimulation (VNS), was approved by the FDA for use in adults in 1997.
"Nearly two-thirds of the 38 children treated with vagal nerve stimulation experienced a reduction in seizures of 50 percent or more," said Ravish V. Patwardhan, M.D., Division of Neurosurgery, University of Alabama, Birmingham, the principal author of the study reported at CNS. Marked or moderate improvement in quality of life was reported in 86 percent of patients. All of the children had either failed, or were not suitable candidates for, conventional treatments for epilepsy prior to the VNS procedure. "Although VNS is not a cure in most cases, it can significantly reduce the number of seizures and improve the quality of life for these children -- some of whom had experienced up to 100 or more seizures a day before they were treated with VNS," he said.
In the technique, a spiral electrode is placed around the vagus nerve through a small incision in the neck, and a wire connects this to a "generator" which is placed underneath the skin of the chest. This generator sends a small current, usually set for every five minutes, to the vagus nerve. It is theorized that this current controls the brain's seizure activity. The stimulator's settings are programmable and adjustable. Also, the child's caretakers are provided with a magnet which, when brought near the stimulator, can send a current immediately and often stop an ongoing seizure.
During the procedure, attempts are made to create two incisions in pre-existing natural skin creases to minimize obvious future scar. The average procedure time was less than one hour in the 38 cases. Procedures were performed primarily by study co-author Paul Grabb, M.D., a neurosurgeon at The Children's Hospital of Alabama.
Patients have usually gone home within 24 hours, often the same day. Patients have then seen their neurologists for follow-up, who are able to turn the stimulator on and adjust settings as needed for an individual child. The patients were followed by neurologists Martina Bebin, M.D. and Jan Mathisen, M.D., co-authors of the study presented at CNS. "This team approach, with careful follow-up between patients' families, the neurosurgeons, and the neurologists, has resulted in some of the successes noted in our study," Dr. Patwardhan said.
The device was placed successfully in all 38 patients without serious complications or adverse effects during the procedure. Some of the more common side effects included hoarseness, cough or swallowing discomfort, but most of these were temporary and went away over time.
An estimated 2.3 million Americans have epilepsy, including 300,000 children. Of these, approximately 25 percent cannot adequately be controlled by medications. Standard treatments for epilepsy have included anti-seizure medications, as well as cerebral surgery to remove seizure- causing portions of the brain if possible. "Surgery sometimes cannot be performed if the seizure activity originates from multiple areas in the brain or is in an area where surgery might result in an unacceptable loss of brain function," Dr. Patwardhan said.
Children in the study included 21 males and 17 females ranging in age from 11 months to 17 years. Results were better in children whose epilepsy began when they were older than 1 year of age. Of the 38 patients studied by Dr. Patwardhan and his co-investigators, 26 percent reported a 90 percent or greater reduction in seizure frequency, 37 percent had a 50 percent to 90 percent reduction and 37 percent had less than 50 percent reduction in seizure activity. No change in seizure frequency was seen in 18 percent. Overall, the mean reduction in seizure frequency was 61 percent at six months follow-up. Reduction in seizure frequency also improved as more time passed following VNS implantation. "These results are better than those seen in most VNS studies in adults, and suggest that this technique may improve quality of life if used earlier than later, according to our data. Several of the patients in our population had suffered uncontrolled seizures for well over five years; traditionally, seizur medications have been tried for two years before declaring a patient to be poorly controlled by medications alone. Multiple years of seizure activity may do serious damage to the brain that may be avoided in some cases if VNS is initiated sooner." Dr. Patwardhan said.
New Directions in VNS
Also at the CNS meeting, Dr. Patwardhan reported on an experimental technique in which cadavers and animal models were used to test the effectiveness of stimulating a branch of the ninthcranial nerve, known as Hering's nerve, to treat seizures. "According to our preliminary research, Hering's nerve stimulation (HNS) can successfully control the majority of focal seizures. This technique may be superior to VNS since, according to our data, either left- or right-sided HNS can be performed, as opposed to only left-sided VNS being presently approved (due to potentially dangerous heart-related side effects with right-sided VNS). With no apparent dangerous side effects, our preliminary study showed seizure control rate of 75 percent in our model. We hope to advance this technique to human Phase I trials," Dr. Patwardhan said.
"In talking with the families of patients who dramatically improved following VNS, the excitement in a mother's voice was clear. In contrast but equally important, the disappointment in the voice of a mother whose child still suffered uncontrollable seizures (despite all possible presently available treatments, including VNS) was disheartening. By introducing the technique of Hering's nerve stimulation, we hope we can offer hope to those patients and their families who cannot benefit from presently available therapy for seizure control."
Co-authors of a paper on VNS in children presented by Dr. Patwardhan at the CNS meeting are Benjamin Stong, B.S.; Martina Bebin, M.D.; Jan Mathisen, M.D.; and Paul A. Grabb, M.D.
Co-authors of the research on HNS are Shane Tubbs, M.S.; Cheryl Killingsworth, D.V.M.; Dennis Rollins, M.S.; William M. Smith, Ph.D.; and Raymond Ideker, M.D., Ph.D.
The Congress of Neurological Surgeons is a professional medical association devoted to the advancement of neurological surgery, with nearly 4,200 members in the United States and Canada. The mission of CNS is to promote the public welfare through the advancement of neurosurgery, commitment to excellence in education and dedication to research and scientific knowledge. Neurological surgery is the medical specialty concerned with the diagnosis and treatment of disorders affecting the nervous system, brain, spinal cord and spinal column. For more information, visit the CNS Web site at http://www.neurosurgery.org.
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