Vagus Nerve Stimulation: What You Should Know
Epilepsy is a common neurological condition suffered by millions of people around the world. A myriad of medications has been introduced to battle the illness, however, still around a quarter of the patients do not respond to them. This condition is known as drug-resistant epilepsy. However, there are multiple treatment options available for these patients one such option being Vagus Nerve Stimulation (VNS).
What is Vagus Nerve Stimulation?
As the name implies this is a device that will be implanted in the neck and will provide constant electrical stimulation to the vagus nerve, which is the 10th cranial nerve arising from the brainstem and traversing through the neck, chest, and abdomen. The device will be powered by a small battery implanted beneath the skin just below the left clavicle. The VNS first came in 1997. VNS is FDA (Food and Drug Administration) approved for epilepsy in children 4 years and older and adults, and in Europe there is no age limit.
How is Vagus Nerve Stimulation Implanted?
The procedure is simple and most neuro-, cardiac and ENT surgeons perform it as a one-day surgery. Here via a small incision, a wire is wrapped around your left vagus nerve and then passed just beneath the skin and connected to the device which is placed below your left clavicle on your chest.
How Does Vagus Nerve Stimulation Work?
The exact way the VNS work is still not fully understood, however, it is thought that it interacts with the brain through the connections with the brainstem, which receives signals from the vagus nerve. Then connects to the Thalamus and the brain cortex which provides soothing neurotransmitters which inhibits the brain's excess electrical activity which causes epileptic activity, preventing seizures. In the event of a seizure, the device will detect it and provide extra stimulation to stop the seizure.
To do this, the VNS needs multiple sessions of programming to reach the target settings which takes a few months to achieve. We program the device manually to deliver the small pulses of electricity and increase slowly to reach our goal. It was done manually but now advanced programming is available, so the device does so on its own.
Therefore, it will take a few months to get the full effect. So do not be surprised if you continue to have seizures right after the surgery. It takes a little bit of time to be optimized.
How Long does the VNS Battery Last?
The battery life depends a lot on the settings of the device and how much electricity it is giving and the frequency of stimulation. The typical battery life is between 4 to 10 years, so in the regular settings, usually lasts for about 7 years.
Once low it can easily be replaced via a simple procedure done under local anesthesia where the device on your chest is taken out and the battery replaced, without touching the wires in the neck.
How Effective is Vagus Nerve Stimulation?
VNS gets better with time. It is expected to cut seizures by 50% in 50% of the cases, this is the usual initial response, however, this improved with time to 70% or more over the following year or two.
The chances of complete seizure freedom vary it is fair to say based on many studies that the seizure freedom rate is about 10%.
Moreover, it helps reduce the effects of the seizure so the seizures might be less intense and the recovery is faster allowing you to get back on track faster and feel better even after having a seizure. VNS can even lower the chances of dying from epilepsy called Sudden Unexpected Death in Epilepsy (SUDEP).
However, as it’s not a cure so the user may not feel that it helps until they stop using it.
How Much Does Vagus Nerve Stimulation Cost?
The cost of VNS varies dramatically from one place to another so it is almost impossible to predict the cost, however, you can find out by reaching out to your neurologist and hospital and they should be able to provide the exact cost.
Are you a Candidate for VNS?
As mentioned, this is one treatment option for drug-resistant epilepsy. The best option is surgery to resect an epileptic focus most probably a scar in your brain. However, in some cases, it may not be possible. There may be multiple foci or the scar may be at an unresectable location of your brain or we may simply not know where the scar is. For these people, VNS remains a viable option.
The vagus nerve stimulation works for any type of epilepsy, although best for focal epilepsy it may be used for multifocal or even generalized epilepsy.
Like any procedure, there are some concerns. One is those suffering from heart conduction issues like heart block or arrhythmia, as the vagus supplies the heart but it’s mostly the right nerve which is why we use the left. Another group is the people suffering from sleep apnea, however, the device can be calibrated to change its discharge from day to night. Therefore, these are just concerns to be worried about on an individual basis rather than contraindications.
What Are the Side Effects of Vagus Nerve Stimulation?
The side effects of VNS can include local effects on the vagus nerve like cough, hoarseness of voice, throat and neck pain, worsening of sleep apnea and rarely procedure related complications like nerve damage, bleeding and infection. Usually the side effects improve with time or with adjusting the settings of the VNS decide like lowering the frequency of stimulation and the pulse width.
How to know whether it’s the device with a normal cold is to see the frequency you get the cough or hoarseness, as VNS works in pulses mostly lasting 30 seconds every 5 minutes, or you can place a magnet on the device to switch it off and see if the cough persists meaning it's not the VNS causing it.
If unbearable or ineffective the VNS can always be removed however it's worthwhile to allow a trial period of 1 to 2 years to see positive effects. Here we remove only the device leaving behind 1 to 2 centimeters of wire which will stick to the vagus after the initial surgery.
Can You Stop Taking Your Drugs after Vagus Nerve Stimulation?
Unfortunately, no! VNS is a palliative therapy and not a cure for your epilepsy. There is a chance to reduce the dose and the number of medications you use but VNS will not replace them, but work together with them.
How To Live and Travel With VNS?
Know that all security devices and metal detectors do interfere with the VNS, so you should tell security that you have a medical device, and they will do a patting test.
Regarding medical scans CT scans or X-rays can be done without an issue. But MRI needs care, as you cannot scan the area (neck and upper chest) the device is located in and the device needs to be switched off before the scan.
Phones with charging magnets such as the iPhone 12 and above can interfere if it comes close to the VNS device.
And you should understand that the device can’t control you, or be tracked by others and can only be programmed by the programmer at your doctor’s office.
What’s in the Future of Vagus Nerve Stimulation?
Transcutaneous vagus nerve stimulation (tVNS) is a noninvasive stimulator that is placed on the ear lobe and stimulates the auricular branch of the vagus nerve via a small earphone-like stimulator. It’s been approved for use in Europe and works over your skin without the need for surgery.