The vagus nerve is the longest and most complex of the 12 pairs of cranial nerves that originate from the brain. It transmits information to and from the brain to tissues and organs throughout the body.

The name “vagus” comes from the Latin term for “wandering.” This is because the vagus nerve wanders from the brain into organs in the neck, chest, and abdomen.

It is also known as the 10th cranial nerve or cranial nerve X.

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The vagus nerve has two bunches of sensory nerve cell bodies, and it connects the brainstem to the body. It allows the brain to monitor and receive information about several of the body’s different functions.

The nerve and its related parts provide multiple functions within the nervous system. The vagus nerve contributes to the autonomic nervous system, which comprises the parasympathetic and sympathetic divisions.

The vagus nerve is responsible for certain sensory activities and motor information for movement within the body.

Essentially, it is part of a circuit that links the neck, heart, lungs, and the abdomen to the brain.

The vagus nerve has a number of different functions. The four key functions of the vagus nerve are:

  • Sensory: From the throat, heart, lungs, and abdomen.
  • Special sensory: Provides taste sensation behind the tongue.
  • Motor: Provides movement functions for the muscles in the neck responsible for swallowing and speech.
  • Parasympathetic: Responsible for the digestive tract, respiration, and heart rate functioning.

The nerve also helps to balance the autonomic nervous system, which is divided into two areas: sympathetic and parasympathetic. The sympathetic side increases alertness, energy, blood pressure, heart rate, and breathing rate. People may describe it as the “fight or flight” component.

The parasympathetic side, which the vagus nerve is heavily involved in, decreases alertness, blood pressure, and heart rate, and helps with calmness, relaxation, and digestion. As a result, the vagus nerve also helps with defecation, urination, and sexual arousal. People may describe the parasympathetic side as the “rest and digest” component.

Other vagus nerve effects include:

  • Communication between the brain and the gut: The vagus nerve delivers information from the gut to the brain.
  • Relaxation with deep breathing: The vagus nerve communicates with the diaphragm. With deep breaths, a person often feels more relaxed.
  • Lowering the heart rate and blood pressure: If the vagus nerve is overactive, it can lead to the heart being unable to pump enough blood around the body. In some cases, excessive vagus nerve activity can cause loss of consciousness and organ damage.
  • Fear management: The vagus nerve sends information from the gut to the brain, which is linked to dealing with stress, anxiety, and fear – hence the saying, “gut feeling.” These signals may help a person to recover from stressful and scary situations.

Stimulation of the vagus nerve is a medical procedure that is used to try to treat a variety of conditions. It can be done either manually or through electrical pulses.

The effectiveness of vagus nerve stimulation has been tested through clinical trials. Consequently, the FDA has approved its use to treat two different conditions.

Epilepsy

In 1997, the FDA allowed the use of vagus nerve stimulation for refractory epilepsy.

This involves a surgeon placing a small, electrical device, similar to a pacemaker, in a person’s chest. A thin wire known as a lead runs from the device to the vagus nerve.

The surgeon places the device in the body through surgery under general anesthesia. The device then sends electrical impulses at regular intervals, throughout the day, to the brain via the vagus nerve to reduce the severity, or even stop, seizures.

Side effects of vagus nerve stimulation for epilepsy include:

  • hoarseness or changes in voice
  • sore throat
  • shortness of breath
  • coughing
  • slow heart rate
  • difficulty swallowing
  • stomach discomfort or nausea

People using this form of treatment should always tell their doctor if they are having any problems, as there may be ways to reduce or stop these.

Depression

In 2005, the FDA approved the use of vagus nerve stimulation as a treatment for depression that has not responded to other forms of treatment.

This treatment may work by activating the noradrenaline pathway and anti-convulsant system in the brain.

Headache disorders

In 2017, the FDA approved gammaCore, which is a handheld, noninvasive vagus nerve stimulator, for treating episodic cluster headache.

Research from 2023 suggests that this device also shows promise for managing migraine attacks.

With the vagus nerve having pathways to almost every organ in the body, researchers are looking to see if stimulation can help other conditions.

Some conditions that vagus nerve stimulation may help with include:

Additionally, scientists are researching a noninvasive form of vagus nerve stimulation called transcutaneous auricular vagus nerve stimulation (taVNS). Research from 2017 indicated that taVNS may have potential for treating migraine, while research from 2020 may help with neurorehabilitation, such as after a stroke, and motor learning in neonates (newborn infants).

However, more research into the safety and efficacy of vagus nerve stimulation for all of these conditions is necessary.

The vagus nerve has a range of functions, including sensory, motor, and parasympathetic functions.

Vagus nerve stimulation has been approved by the FDA to treat epilepsy and depression. Research into its efficacy and safety for treating other conditions, such as rheumatoid arthritis, inflammatory bowel disease, and Alzheimer’s disease, is ongoing.