Nerve stimulation system reduces epileptic seizures
December 1, 2000 2 minutes read
Nerve stimulation system reduces epileptic seizures
Results improve over time
A new treatment option holds great promise for patients with refractory epilepsy who have not successfully controlled their seizures with available medications. The largest prospective long-term study to date of vagus nerve stimulation (VNS) indicates that it is not only an effective long-term treatment for reducing seizure frequency in patients with refractory epilepsy but that it actually increases in effectiveness over time.
Researchers lead by Christopher DeGiorgio, MD, professor of neurology at the University of California, Los Angeles, followed 195 patients over a 15-month period. The study, recently published in the journal Epilepsia,1 consisted of an initial three-month randomized and double-blind phase during which patients received a high or active level of stimulation.
At the conclusion of the double-blind phase of the study, results included:
• The median reduction in seizure frequency was 34%.
• After 12 months of stimulation, the participant median seizure reduction increased to 45%.
• 20% of patients involved in the study sustained a greater than 75% reduction in seizure occurrence at 12 months.
"This is the largest long-term prospective study of vagus nerve stimulation ever published," says DeGiorgio. "It shows that the effectiveness of VNS, modest after three months, is substantially improved after one year of long-term follow-up. Twenty percent of patients sustained a 75% to 100% reduction in seizures, increased from only 11% at three months. The median reduction was a very robust 45%. The population chosen had extremely severe epilepsy and had failed multiple medications in the past. VNS does not cause all the drug side effects that medicines cause."
VNS was delivered by the NeuroCybernetic Prosthesis (NCP) System developed by Cyberonics in Houston. Often called the "pacemaker of the brain," the system consists of a pocket watch generator implanted under the skin in a patient’s chest. A lead wire from the device is tunneled up the neck, and coils at the end of the wire are wrapped around the vagus nerve in the neck. Using a laptop computer and a programming wand, the neurologist programs the NCP System to deliver regular, mild electrical stimulation to the vagus nerve.
The system has been clinically proven to decrease, and in some patients, completely eliminate, seizures by conditioning the brain to react better to the interruptions in the brain function common in epilepsy. In addition, patients may pass a magnet over the device when they sense a seizure coming for an extra dose of stimulation to decrease the severity or stop a seizure in its tracks.
Reference
1. DeGiorgio CM, Schacter SC, Handforth A, et al. Prospective long-term study of vagus nerve stimulation for the treatment of refractory seizures. Epilepsia 2000; 41:1,195-1,200.
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