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What is the vagus nerve? -

The vagus nerve is a cranial nerve that sends signals between your brain and different parts of your neck, head, and torso.

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Where in the body? -

There is one vagus nerve on each side of the body. It starts at the brainstem and then passes through the neck to the chest and abdomen.

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Vagus nerve stimulation -

Vagus nerve stimulation (VNS) is a neuromodulation treatment, which means it alters the activity of the nerves.

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Implanted device -

It involves implanting a device that sends regular and mild pulses of electrical energy through the vagus nerve to the brainstem.

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Neuromodulation -

Once it reaches the brain, the electrical charge is sent out to different areas of the brain to alter the ways the cells work.

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Treating epilepsy -

The U.S. Food and Drug Administration (FDA) has approved VNS to treat three separate medical conditions. The first is epilepsy.

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Treating epilepsy -

VNS is used as an add-on therapy for treatment-resistant epilepsy in adults and children older than four years old.

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Treating depression -

VNS is also an approved treatment for adults who have long-term or recurrent major depression.

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Treating depression -

In order to qualify for VNS, a patient with depression must have tried four or more antidepressant treatments without success.

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Stroke rehabilitation -

More recently, VNS has also been approved as an add-on to rehabilitation therapy for people who have suffered an ischemic stroke.

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Stroke rehabilitation -

In stroke rehabilitation, VNS is used to help people recover after moderate to severe loss of arm and hand function.

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How does it work? -

Scientists do not know precisely how VNS works, but they do have a general idea. As a seizure treatment, VNS is believed to improve blood flow to critical areas of the brain.

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As an epilepsy treatment -

It is also thought to alter the chaotic electrical pattern that happens during a seizure, as well as increase the level of neurotransmitters in the brain that may control seizure development.

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As a depression treatment -

In the context of depression treatment, VNS is thought to alter the level of specific neurotransmitters in the brain that help with regulating mood.

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For stroke rehabilitation -

And for stroke rehabilitation, VNS is thought to stimulate the motor cortex area in the brain. This is the area that controls the ability to move the arms and hands.

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What it feels like -

In general, people who have a VNS device fitted are unaware when the device is turned on, and they do not feel the stimulation.

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Side effects -

However, there are some possible side effects, including a tickling feeling in the throat or neck.

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Side effects -

There is also the possibility of becoming hoarse or suffering from a mild cough when the stimulation is on.

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Risks -

In addition to the side effects once the device is fitted, there are also some risks associated with the implantation surgery.

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Risks -

Those risks include infection, pain and inflammation at the incision site, and damage to the vagus nerve or surrounding structures.

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People who can't have VNS -

There are certain people who do not qualify for VNS treatment, including those who are pregnant, have breathing problems, or have heart abnormalities.

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Outcome -

In terms of the expected outcome for VNS, it depends on the problem it is being used to treat. In the case of epilepsy, VNS cannot be considered a cure.

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In epilepsy patients -

In fact, it probably will not stop the seizures completely either. Rather, the aim is to reduce the number, length, and severity of the seizures.

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In epilepsy patients -

According to one study that looked at 454 patients, there was a 50% or greater reduction in seizures in 37% of patients after one year. That percentage rose to 43% after two years, and stayed at 43% after three years.

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In depression patients -

So far, research has not established how effective VNS can be for treating depression. This is why it is used as a last-resort treatment.

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In depression patients -

According to one study that looked at 200 patients with treatment-resistant depression, 20% to 30% of participants reported significant improvement after one year.

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In depression patients -

However, the other participants in the study either did not improve at all, or their symptoms worsened.

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In stroke patients -

As a treatment for stroke rehabilitation, the FDA based its approval on the results of a study that looked at 108 patients.

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In stroke patients -

The study results showed that the patients who received VNS treatment saw more improvement in limb mobility than those who did not receive it.

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The future of VNS -

Going forward, researchers are investigating whether VNS could be used to treat long-term inflammatory disorders, such as rheumatoid arthritis, diabetes, and inflammatory bowel disease (IBS).

Sources: (Cleveland Clinic) (Mayo Clinic)

See also: Recognizing the understated signs of depression

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