Vagus nerve stimulation (VNS)

Vagus nerve stimulation (VNS) is a type of neuromodulation that uses an implanted device, similar to a heart pacemaker, to deliver regular electrical impulses to the brain through the vagus nerve. VNS is approved to treat conditions including epilepsy and depression. 

What is the vagus nerve? 

The 12 cranial nerves occur in pairs, one on each side of the body. They begin in the brain and travel downward to the head, neck, and torso. Cranial nerves deliver information to and from the brain about smell, vision, hearing, and taste as well as digestion and other important body functions. 

The vagus nerve is the tenth cranial nerve and the longest nerve in the body. It is nicknamed the “wandering nerve” because of the long path it takes from the brain down to the intestines. 

The vagus nerve controls digestion, heart rate, breathing, swallowing, speaking, and the immune system. This nerve functions as a major part of the parasympathetic nervous system, also known as the “rest-and-digest” system. The parasympathetic nervous system calms down a stimulated sympathetic nervous system, also known as the “fight-or-flight” system. 

The vagus nerve stimulator is a small, flat, battery-operated device. When the device is on, it sends electrical impulses through a wire to the vagus nerve in the neck.  

These electrical impulses stimulate the vagus nerve to send signals to the lower part of the brain (brainstem). The brainstem then delivers the signals to the rest of the brain. 

An active vagus nerve promotes calm and relaxation, so vagus nerve stimulation helps calm areas of abnormal electrical hyperactivity in the brain. VNS may also raise the level of chemical messengers (neurotransmitters) in the brain and increase blood flow to specific brain regions. 

The battery for the VNS unit typically lasts five to 10 years before requiring a quick outpatient procedure to replace it. 

People with epilepsy who have tried two or more anti-seizure medications without good seizure control may benefit from VNS. VNS is often used along with anti-seizure medications to further improve seizure control. 

VNS may not be recommended in people with: 

• Breathing problems 
• Heart problems 
• Sleep apnea 

Surgery to place the vagus nerve stimulator is an outpatient procedure that usually takes between 45 and 90 minutes. Most people receive general anesthesia to put them to sleep for the procedure. 

During the VNS surgery, your neurosurgeon: 

1. Makes two small incisions—one underneath the collarbone on the left side of your chest for the stimulator device and one on the left side of your lower neck. 
2. Creates a small pocket of space underneath the skin below the incision in your chest for the stimulator device. 
3. Threads a thin, flexible wire through your neck to the vagus nerve. 
4. Connects the other end of the wire to the stimulator device in your chest. 
5. Closes the incisions. 

Most people go home the same day as the procedure and can resume most of their normal activities within one week. 

About two to four weeks after surgery, you have an appointment with your neurologist to activate the stimulator device. You begin with the stimulator at a low level of intensity. Your doctor gradually increases this intensity based on how you feel and how your symptoms respond. 

Your neurologist will give you a handheld magnet, which you or your family members can use to control the stimulator at home. Sweeping the magnet over the stimulator in your chest activates it to deliver an extra burst of electrical impulses during a seizure. 

VNS surgery may cause some temporary side effects as your body gets used to the device, including: 

• Muscle twitching or involuntary movements from the stimulation 
• Pain (neck, throat, or general pain) at the incision site 
• Problems with sensation, such as decreased sense of touch, prickling, or tingling 
• Shortness of breath 
• Vocal or speech changes, coughing, hoarseness, or throat spasms 

Let your doctor know if you notice any of these side effects. 

VNS reduces seizure frequency by about 50 percent in around half of patients. VNS may also help decrease the duration and severity of seizures. People who experience auras (warning signs) before a seizure may be able to stop or shorten the seizure by activating the VNS with the external magnet. 

While complications during VNS surgery are very rare, all procedures carry some risk. Risks of VNS surgery may include: 

• Infection 
• Inflammation or pain at the incision site 
• Vagus nerve damage, causing hoarseness and difficulty swallowing

Penn Medicine’s Comprehensive Epilepsy Center is home to epileptologists and neurosurgeons with decades of experience treating even the most rare and complex seizures. 

People who come to us for care find: 

• Surgical expertise: Our skilled neurosurgery team has decades of experience with vagus nerve stimulation and other implantable devices for epilepsy. Their experience leads to safer surgeries and better results for you. 
• Tailored Treatment: Our collaborative care is focused on creating a treatment plan that’s right for your individual needs. We meet as a team to understand how epilepsy affects you, physically and personally, and use our experience to recommend the most effective treatment options. 
• Long-term follow-up: Our goal is to reduce your seizures and improve your quality of life. Your care doesn’t end when your VNS device is activated. We schedule regular appointments where we make sure the device is controlling your symptoms as effectively as possible.