The recurrent laryngeal nerve (RLN) branches off the vagus nerve in the neck. The RLN is critical for speech as it provides nerve function to muscles in the larynx, our voice box.

People have two RLNs, one on each side of the neck. Instead of following the direction of the vagus nerve down to the chest, the RLN curves back up in the neck. Because it branches off the vagus nerve near the heart, on the left side of the chest rather than in its center, the RLN has an asymmetrical shape.

The RLN supplies most of the muscle groups of the larynx and some parts of the throat. An injury on one side can cause a person to experience hoarseness. Injuries on both sides can cause noisy breathing or airway obstruction.

This article will explain the structure and function of the RLN. It will also explore injuries or conditions that can affect this nerve, their symptoms, and how doctors can treat them.

The recurrent laryngeal nerve.Share on Pinterest
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The RLN branches off the vagus nerve near the heart, on the left side of the chest. This is why the RLN is one of the few nerve pairs that are asymmetrical.

After the RLN separates from the vagus nerve it continues to branch out. The major branches of the RLN include the following:

  • Inferior laryngeal branch: This serves most of the muscles of the larynx.
  • Motor branches: The RLN sends branches to some muscles in the throat — the inferior constrictor and cricopharyngeus — before entering the larynx.
  • General visceral sensory fibers: These are present in the area below the larynx.

The RLN supplies nerve function to the larynx muscles that control the tension of the vocal cords, including their opening and closing.

Without the RLN and the muscles connected to it, a person would not be able to speak. The RLN works closely with these muscles, including the posterior cricoarytenoid muscles, which open the vocal cords, and the interarytenoid muscle, which holds the vocal cords in a closed position.

The RLN also has sensory functions. It delivers information to the brain from the membranes below the larynx and sends sensory fibers to the trachea and esophagus.

People can experience problems with their RLN due to the following:

  • surgery
  • injuries
  • tumors
  • medical conditions

Surgery

A 2017 report states that the RLN can sustain injuries during surgery.

In particular, this can occur in people undergoing thyroid or parathyroid surgery. A cohort study on 648 people undergoing thyroidectomies and parathyroidectomies found injury rates to be 14% and 7%, respectively.

This is because the thyroid gland sits close to the RLN. However, permanent paralysis is rare, occurring in just 1.1% of cases.

Surgery can damage one or both sides of the RLN. If both sides of the RLN have damage, the symptoms may appear immediately.

However, symptoms of severe damage to the RLN, called axonotmesis, usually appear around 3 weeks after the injury. Axonotmesis may lead to a poor outlook.

Injury

Trauma to the throat or surrounding area of the RLN can cause an injury.

Symptoms include a change in voice pitch or noisy breathing. Severe damage or injuring both sides of the RLN may result in a total inability to speak.

If the injury causes paralysis of both RLNs, a person may also experience the following:

Tumors

Tumors in the neck can compress the RLN. This can cause hoarseness, which may be a sign of the advanced status of the tumor.

Sometimes, the surgeon may need to cut off the RLN to access and remove a tumor. However, doctors have developed ways to monitor the integrity of the RLN during surgery and reconstruct it in case of damage.

This can help reduce the risk of permanent paralysis of the vocal cords.

Other conditions

Another condition that can affect the nerve is a cardiovocal syndrome known as Ortner’s syndrome. This can cause paralysis and involuntary tremors in the RLN. People with Ortner’s syndrome often experience hoarseness.

A person may also have symptoms if a part of their body is compressing their RLN.

Trauma can lead to RLN injury. Symptoms of a damaged RLN include:

  • a hoarse or weakened voice
  • loss of voice
  • noisy breathing
  • difficulty swallowing
  • difficulty breathing

A person with RLN injury may also experience paralysis of their posterior cricoarytenoid muscle, which is responsible for opening the vocal cords.

This paralysis can lead to breathing problems. Severe damage to both sides of the posterior cricoarytenoid muscle can lead to the inability to speak.

People should contact a doctor if they notice any change in their voice, swallowing, or speaking ability.

If they experience difficulty breathing or their voice sounds different after a trauma involving their neck, this may be a symptom of RLN injury.

The doctor will perform a physical examination to assess the potential injury and functionality of vocal cords. If the doctor suspects a tumor or nerve injury, they may recommend an imaging test, such as a CT scan.

Treatment for an RLN injury includes voice therapy or surgery. Doctors may also use reinnervation techniques to try and repair the nerve, depending on the extent of the injury.

Other types of surgical treatment for RLN injury include:

  • Type 1 thyroplasty: During this procedure, the surgeon will make an external incision and place an implant that will permanently move the injured vocal cord.
  • Arytenoid adduction: The surgeon will make a permanent suture, a type of stitch, through the muscles of the arytenoid cartilage. This will pull the injured vocal cord where paralysis has occurred after the RLN injury.
  • Injection laryngoplasty: The surgeon will inject a material into the injured vocal cord during this procedure. Doctors can use different types of material to fill and move the vocal cord, including hyaluronic acid derivatives and collagen derivatives.

The outlook for RLN injury may vary depending on the severity of the damage.

Damage can be permanent or temporary. Whether a person can completely recover from their injury will depend on the complexity of the RLN injury.

After a mild injury, a person should be able to recover in 6–8 weeks.

Because recovery will differ for each individual, a person with an RLN injury will need to consult a doctor about their specific case.

The RLN provides nerve function for the larynx and throat muscles, which control swallowing, breathing, and the movement of the vocal cords. Surgery, trauma, and other medical conditions can affect the function of the RLN, causing changes in the voice pitch.

In severe cases, a person may have difficulty breathing and swallowing due to changes in the movement of the larynx muscles or paralysis of their vocal cords.

Doctors can assess the condition of the RLN through a physical examination and imaging tests. After diagnosing an injury or condition affecting the nerve, they can recommend the most effective treatment. Depending on the extent and severity of the injury, this may include surgery or voice therapy.