In epilepsy

Vagus nerve stimulation doesn’t cure epilepsy. It probably won’t completely stop your seizures, either, and you’ll need to continue taking anticonvulsant medication. The goal of VNS is to reduce the number, length and severity of your seizures.

A 454-patient study showed a 50% or greater reduction in seizures in 37% of patients at one year, 43% at two years and 43% at three years.

In depression

Research remains unclear on how well VNS works to treat depression. So, it’s usually not recommended until medications, in combination with psychotherapy, have first been tried.

The FDA based its approval on studies involving more than 200 people with treatment-resistant depression. After one year, 20% to 30% of people with depression reported significant improvement. But other people with depression didn’t improve or their symptoms worsened.

In stroke rehabilitation

The FDA based its approval on the results of a 108-patient study. Patients, split into a 53-patient study group and a 55-patient control group, were asked to complete 300 to 400 physical therapy exercises for 90 minutes a day, three times a week for six weeks. The study group received VNS throughout the 90-minute sessions. People in the treatment group had an average limb mobility score increase of 5 points compared to a 2.4 point increase in people in the control group. About 47% of those in the treatment group saw a 6 point or more improvement in limb mobility score 90 days post-therapy compared with a 24% improvement in people in the control group.

Common side effects of vagus nerve stimulation include:

• Coughing.
• Hoarseness.
• Change in voice.
• Neck pain or throat pain or tickling.
• Shortness of breath/trouble breathing (dyspnea).
• Trouble speaking (dysphonia).
• Trouble swallowing (dysphagia).
• Headache.

If you experience these side effects, they may lessen, or you may become less bothered by them over time. If you can’t tolerate the side effects, it might be possible to adjust the electrical impulses or the device may be temporarily or permanently turned off.

Serious side effects include:

• Vocal cord paralysis.
• Infection.
• Horner’s syndrome.
• Muscle weakness in your lower face (facial muscle paresis).
• Your heart may stop beating (cardiac arrest).
• Sudden unexplained death. This doesn’t happen at a higher rate than naturally seen in a population of people who have epilepsy.
• Mechanical complications like a break in the lead wire or device malfunction.

Device adjustment and operation

You’ll return to your healthcare provider’s office in two to four weeks to turn on the stimulator device (or increase the stimulation if it’s already been turned on). The device is programmed by your healthcare provider using a computer, programming software and programming wand. The device will be set to deliver electrical impulses (measured as strength of current) to your vagus nerve at a certain pulse frequency (measured in Hertz), for a certain length of time (measured in microseconds to seconds) and on a specific time on/time off cycle (measured in seconds to minutes). Settings usually start at low levels to see how your symptoms respond and to check for side effects.

The device’s on/off cycle is selected by your healthcare provider. But you’ll also be given a hand-held magnet that can be swiped over the device to send extra stimulation to your brain if you sense a seizure is about to happen. When used during home rehabilitation exercises following a stroke, swiping the magnet over the device activates it to begin 30 minutes of stimulation. Holding the magnet over the device turns the stimulator off. Removing the magnet will resume your healthcare provider’s programmed stimulation cycle. In some batteries for epilepsy, an increase in your heart rate can also trigger activation.

You’ll need to see your healthcare provider as directed to ensure the device has remained in the correct position in your chest and is working properly. Adjustments can be made in device programming if needed.

You may not be a candidate for vagus nerve stimulation if:

• You’re pregnant.
• Have breathing problems, including asthma, sleep apnea, chronic obstructive pulmonary disease or other lung diseases and disorders.
• Have active peptic ulcer disease.
• Have insulin-dependent diabetes mellitus.
• Have only one vagus nerve.
• Have dysautonomias, which involves abnormal functioning of your autonomic nervous system.
• Are receiving other forms of brain stimulation.
• Have heart arrhythmias or other heart abnormalities.
• Have a history of schizophrenia, schizoaffective disorder, delusional disorders or rapid cycling bipolar disorder.
• Have previous surgery to your left neck involving removing part of your vagus nerve.

You’re usually unaware when the device is on or feel the stimulation. However, you may have a tickling feeling in your throat or neck, your voice may become hoarse or you may have a mild cough when the stimulation is on.

If the stimulation bothers you in any way, call your healthcare provider. They can adjust the programming to lower the amount of stimulation.

Vagus nerve stimulation (VNS) to treat three medical conditions.

For use in epilepsy

• VNS is approved as add-on therapy for focal (partial) seizures in adults and children four years of age and older when medications haven’t controlled their seizures.

For use in depression

• VNS is approved for adults 18 years of age or older who have long-term or recurrent (repeating) major depression that hasn’t responded to four or more antidepressant treatments.

For use in stroke rehabilitation

• VNS is approved as an add-on to rehabilitation therapy for people who have moderate to severe loss of arm and hand function due to ischemic (blocked blood flow) stroke.

Nerve damage

Damage to the vagus nerve can result in a range of symptoms because the nerve is so long and affects many areas.

Potential symptoms of damage to the vagus nerve include:

• difficulty speaking
• loss or change of voice
• difficulty swallowing
• loss of the gag reflex
• low blood pressure
• slow or fast heart rate
• changes in the digestive process
• nausea or vomiting
• abdominal bloating or pain
• depression and anxiety in people with breathing problems or heart disease

The symptoms someone might have depend on what part of the nerve is damaged.

Your vagus nerve is one of 12 pairs of cranial nerves that send electrical signals between your brain and different parts of your neck, head and torso. They control many of your body's functions.

Your vagus nerve is cranial nerve X (10) and is the longest cranial nerve. You have one vagus nerve on each side of your body. Both start at your brainstem and pass through your neck to your chest and abdomen.

Your vagus nerve is part of a circuit that links your neck, heart, lungs and abdomen to your brain.

Vagus nerve stimulation (VNS) is a type of neuromodulation, which is a treatment that alters the activity of nerves. Vagus nerve stimulation involves implanting a device that sends regular, mild pulses of electrical energy to your brainstem through your vagus nerve in your neck. After reaching your brainstem, the electrical charge is discharged to different areas of your brain to change the way brain cells work.

Vagus nerve stimulation works like a pacemaker for your heart. In fact, VNS is sometimes called a “pacemaker for the brain.”

VNS is a treatment option that you and your healthcare professional might consider after other traditional treatments haven’t been successful. The use of VNS is limited to a select group of individuals who have treatment-resistant epilepsy or treatment-resistant depression. More recently, VNS has been approved as a rehabilitation aid for select people who’ve had a stroke.

You can return to your everyday activities 48 hours after your device is implanted. Your stitches are self-absorbing, so they don't need to be removed.

Common risks of vagus nerve stimulation include:

• Infection.
• Pain and inflammation at the incision sites.
• Damage to your vagus nerve or surrounding structures.

Tell all of your healthcare providers that you have a vagus nerve stimulator device before having any medical procedures or imaging tests, such as magnetic resonance imaging (MRI). This test can interfere with your device.

Before your surgery, your healthcare provider will perform a physical exam. You may have blood drawn to ensure you don’t have any health problems that could cause concern.

Surgery to implant the device can be done as an outpatient procedure. Some surgeons might recommend that you stay overnight, though.

You’ll need to have the battery replaced about every six years (some batteries last as short as one year to as long as 15 years). When the battery level is low, the entire stimulator is replaced. This is done in a short procedure that only requires a small incision in your chest wall.

Researchers don’t know precisely how vagus nerve stimulation (VNS) works.

As an aid to control seizures, VNS is thought to:

• Improve blood flow to critical areas of your brain.
• Alter the chaotic electrical pattern that happens during a seizure.
• Increase the level of neurotransmitters (specifically norepinephrine and serotonin) in your brain that may control seizure development.

As an aid to manage depression, VNS is thought to:

• Alter the level of specific neurotransmitters in your brain that play a role in regulating mood.

As an aid for stroke rehabilitation, VNS is thought to:

• Stimulate the motor cortex area in your brain, which controls your ability to move your arms and hands.

No. There are external or commercial VNS devices. However, these external products can’t match the frequencies and voltages used in implanted devices. The electrical signals they produce have to pass through your skin and neck muscles. They’re not precise enough to access and regulate the specific activity of your vagus nerve, as an external device isn’t attached to your actual nerve.

The long-term side effects of commercial VNS devices are yet to be fully known. If you’re interested in commercial VNS devices, it’s best to talk with a healthcare provider specializing in this area.