Quick GuideEpilepsy: Symptoms, Causes and Treatment
When Is VNS Used?
Brain cells communicate by sending electrical signals in an orderly pattern. In people with epilepsy, this pattern is sometimes disrupted due either to an injury or the person's genetic make-up, causing brain cells to emit signals in an uncontrolled fashion. This creates over-excitement, somewhat like an electrical overload in the brain, leading to seizures. Seizures can be produced by electrical impulses from throughout the brain, called generalized seizures, or from a small area of the brain, called partial seizures.
Most people with epilepsy can control their seizures with medications called anti-convulsant or anti-seizure drugs. About 20% of people with epilepsy do not respond to anti-seizure medications. In some cases, surgery to remove the part of the brain causing the seizures may be used. VNS may be a treatment option for people whose seizures are not controlled by anti-seizure medications and who are not considered good candidates for surgery; for example, if their seizures are produced throughout the brain (generalized).
How Does VNS Work?
It is not known exactly how VNS works. It is known, however, that the vagus nerve is an important pathway to the brain. It is thought that by stimulating the vagus nerve, electrical energy is discharged upward into a wide area of the brain, disrupting the abnormal brain activity responsible for seizures. Another theory suggests that stimulating the vagus nerve causes the release of special brain chemicals that decrease seizure activity.
What Are the Risks of VNS?
The risks of VNS include injury to the vagus nerve or nearby blood vessels, including the carotid artery and jugular vein. In addition, there are risks associated with any surgical procedure, such as infection, bleeding and an allergic reaction to the anesthesia.
What Are the Benefits of VNS?
VNS is not a cure, and the total elimination of seizures is rare. However, many people who undergo VNS experience a significant (more than 50%) reduction in the frequency of seizures, as well as a decrease in seizure severity. This can greatly improve the quality of life for people with epilepsy.