The Vagus is one of the major nerves in the body. It runs up from the abdomen into the brain and controls many functions. The vagus nerve on the right side of the body can't be treated because it helps to control the way the heart works. Vagal Nerve Stimulator (VNS) involves a small operation to insert a wire electrode into the patient's neck. The advantage of VNS is that it isn't associated with the common side effects seen with anti-epileptic drugs, such as sedation, light-headedness or tremors.