Vagus Nerve Stimulation (VNS)
Treatment of seizures when medications are ineffective and surgery is not an option
“This next generation of neuromodulation therapy allows for much more precise monitoring of when patients are having seizures and may also allow for the identification of patients at higher risk for sudden unexpected death in epilepsy (SUDEP).” — Angus Wilfong, MD, Associate Director of Barrow Neurological Institute at Phoenix Children’s Hospital and Chief of Pediatric Neurology at Phoenix Children’s
What is Vagus Nerve Stimulation (VNS)?
A VNS is a device used to treat seizures when medicines are not effective and surgery is not possible for a cure. VNS consists of a pacemaker-like generator placed underneath the skin on the chest and is attached to thin wires threaded up to, and wrapped around, the vagus nerve in the neck. It is programmed by the physician to stimulate the vagus nerve regularly with the goal of reducing the abnormal electrical activity and frequency of seizures occurring in the brain. The VNS can also be activated by a patient or caregiver to stop seizures just as they are beginning.
When to consider VNS for your child?
Many children with seizures do not have a single, focused area of seizure onset. Others may have a seizure onset zone in a critical area of the brain. When medications fail to control seizures in these children, treatment options are limited and the child should be considered for VNS.
Is VNS the right choice for your child?
If your child loses consciousness during seizures, and if those seizures are not being controlled by medication, they may benefit from vagal nerve stimulation.
While not all children see improvement, VNS can result in fewer or less severe seizures. In all cases, however, children need to continue to take anti-epileptic medication as they did before the stimulator was inserted. In some cases, your pediatric neurologist may recommend the use of medication be reduced a few months after vagal nerve stimulation has begun if there is a very positive result. This can reduce the side effects of some of the medications on energy level and thinking.
The procedure is performed on children as young 4 years old. It is not an option for children with severe asthma or severe heart disease, particularly those with an irregular heartbeat.
Implantation of the VNS by our pediatric neurosurgeons requires two small incisions on the left side: one in the neck in order to access to vagus nerve between the carotid artery and the internal jugular vein, and one on the chest wall just above the nipple where the battery-operated generator (which is the size of a silver dollar) is placed.
In the neck, the electrode leads are wrapped around the vagus nerve, and the wires are tunneled beneath the skin to the chest incision being connected to the generator or “pacemaker”. The surgery takes 45 minutes to an hour and is performed under general anesthesia. In general, VNS implantation surgery is an outpatient procedure, and patients are observed for 2-3 hours post-op, prior to discharge.
In many cases, the VNS is activated at low settings in the operating room at the time of implantation or at the first post-surgical visit.
How effective is VNS?
A reasonable goal for VNS is seizure reduction, rather than seizure-freedom. Indeed, not every child benefits significantly from VNS, but those who do, may experience 50% or more reduction in their seizure frequency. The VNS device often becomes more effective the longer it is in, and physicians typically know within six months if the VNS is helping to control the child's seizures.
Follow-up for the VNS Procedure
We will assess your child in 10 – 14 days for a wound check, and may turn on or adjust the generator at that time. Parents will be shown how to use a magnet to control a seizure. Waving the magnet over the generator will start a new cycle at higher parameters which may stop or shorten a seizure.
Are there any side effects to VNS?
Side effects of VNS therapy include alterations in voice or throat sensation, throat pain and a mild cough have been observed in children with VNS; however, these symptoms tend to improve over time. Additionally, a hoarseness and discomfort can occur in the neck when the generator is on. This indicates the VNS is functioning. Overall, the incidence of children experiencing serious complications or unanticipated outcomes has been rare and outcomes have been excellent.
Diana Larocque, Neurology Nurse Program Coordinator