Vagus Nerve Stimulator (VNS)
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The Vagus Nerve Stimulator (VNS) is an exciting development in the treatment of epilepsy. VNS electrically stimulates the left vagus nerve in the neck, reducing the severity and frequency of seizures in people who have epilepsy.
About the size of a hockey puck, the VNS generator is implanted below the left collarbone. It stimulates two spring-shaped electrodes which are wrapped around the vagus nerve in the left side of the neck. A doctor then programs the device to provide a special cyclical stimulation sequence.
A VNS doesn’t sense seizures. Instead, it sends a programmed, repetitive sequence of stimulation to the brain through the vagus nerve and brain stem. Although we don’t yet understand how this technique inhibits seizures, it clearly scrambles some of the brain’s synchronous discharges, which mark clinically recognizable seizures.
The VNS also emits a special sequence when a magnet passes over the device. If patients can sense the onset of a seizure, they can use this feature to minimize or abort an episode. Caretakers of a patient experiencing a seizure can likewise shorten the seizure, allowing for faster recovery. A VNS is used as adjunct therapy in patients whose epilepsy is poorly controlled through medication. The device is manufactured by Cyberonics Corporation of Houston, Texas.
