What is the Recurrent Laryngeal Nerve?
The recurrent laryngeal nerve (RLN) supplies all the muscles in the larynx (voice box) apart from the cricothyroid muscles. The nerves control the movement of the larynx and the vocal cords. The larynx is involved in producing speech, breathing and it also protects the trachea.
Where is the Recurrent Laryngeal Nerve?
There are two recurrent laryngeal nerves and they branch of the vagus nerve which is the 10th cranial nerve. The nerves then exit the skull and travel down through the neck with the carotid arteries. The left nerve passes under the aortic arch and the right nerve passes under the right subclavian artery. The nerves then pass behind the outer lobes of the thyroid gland and enter into the larynx.
Recurrent Laryngeal Nerve Injury
When the recurrent laryngeal nerve becomes injured it can cause serious problems. The nerve can be damaged in a number of ways and this then affects the way the larynx works. The damage can also cause breathing problems which, in some cases, can be life threatening.
If the recurrent laryngeal nerve is damaged, the symptoms include:
- Loss of voice
- Weakened voice
- Respiratory problems (difficulty breathing)
- Difficulty swallowing
- Persistent coughing
- Sore throat
If you have any of these symptoms you should seek medical advice at the earliest opportunity.
Injury to the recurrent laryngeal nerve is one of the main complications resulting from thyroid surgery. Because the nerve is so close to the outer lobes of the thyroid gland, it is extremely vulnerable. The nerve can be cut or bruised which could result in temporary or permanent damage.
Scar tissue resulting from thyroid surgery can also damage the recurrent laryngeal nerve. Fibrous scar tissue can compress the nerves so that they are unable to function correctly. Scar tissue can usually be broken up to free the nerve.
In rare cases, both recurrent laryngeal nerves can be damaged during thyroid surgery. When both nerves are damaged, the vocal cords may not close and air cannot reach the lungs. When this happens, a surgeon will need to perform a tracheotomy to enable the patient to breathe.
Some medical procedures can cause injury to the recurrent laryngeal nerves. Inserting an IV needle into the neck or throat can pierce or bruise the nerves. If a tube has to be used to aid a patient’s breathing, this can also damage the nerves.
Nasogastric tubes, used for intubation and feeding, can also damage the recurrent laryngeal nerves. When the tube has been inserted into the nose, it passes through the esophagus. This can cause bruising to the area which then damages soft tissue, muscles and nerves.
The left recurrent laryngeal nerve can also be damaged during open-heart surgery. However, this is rare. The operation itself is traumatic and can impair the nerve and other tissue. Manual manipulation of the heart during the surgery can also cause injury to the nerve.
Any kind of neck injury can cause damage to the recurrent laryngeal nerve. Injuries such as breaks, fractures and twisted necks will put strain on the area which can, in turn, affect bones, muscles, soft tissue and nerves. Whiplash puts excessive stress on the neck and this can also lead to recurrent laryngeal nerve damage.
Tumors in the neck or high up in the chest could also damage the recurrent laryngeal nerve. A tumor can put pressure on the nerve which compresses or damages it. A tumor can also prevent blood from getting to the nerve which then affects the way it communicates.
Most tumors, whether benign or malignant, will be removed by a surgeon. Any type of surgery carries risks and the recurrent laryngeal nerve can be damaged during the surgery to remove the tumor. If the tumor is attached to the recurrent laryngeal nerve, the surgeon may have to remove the tumor and the nerve.
In some cases, a tumor may be treated with radiation therapy, either before surgery or as an alternative treatment. The radiation targets the tumor but it also damages healthy cells and nerves in the same area. If a tumor is targeted in the neck area, the recurrent laryngeal nerve is at great risk of damage.
Blunt trauma can damage the recurrent laryngeal nerve. A heavy blow to the throat or upper chest area can injure the nerve and symptoms could develop. A common cause of neck trauma is in a motor accident, where the compression from a seatbelt causes an injury to the victim.
Blunt trauma can also occur when playing contact sports, such as football or rugby. Combat sports, for example, boxing, judo and wrestling, also put people at risk of blunt trauma to the throat. Neck injuries can occur when playing such sports, which may lead to recurrent laryngeal nerve damage.
If the recurrent laryngeal nerve suffers a penetrating trauma this could also lead to complications. When a sharp object pierces the neck or throat, the recurrent laryngeal nerve is at risk. Penetrating trauma is a serious injury and the damage to the nerve could be permanent.
In rare cases, a viral infection can compress the recurrent laryngeal nerve and lead to vocal cord palsy. The varicella zoster virus, which causes chickenpox and shingles, has been linked to vocal cord palsy. The effects on the nerve are usually noticed a few days after contracting the airborne virus.
Poor circulation can also impair the nerves when they don’t receive an adequate flow of blood. Healthy nerves and the surrounding tissue need a constant supply of blood to function. The brain and nervous system uses 20% of the body's oxygen.
Recurrent Laryngeal Nerve Palsy
Recurrent laryngeal nerve palsy occurs when the recurrent laryngeal nerve or vagus nerve becomes damaged. The condition paralyzes the larynx on one or both sides, depending on the severity of the damage. The condition is rare but serious and medical attention will be required.
The symptoms of recurrent laryngeal nerve palsy include:
- Loss of voice
- Choking due to food and drink entering the windpipe
- Noisy breathing
- Loss of gag reflex
- Inability to cough or clear mucus from the throat
There are some treatments for recurrent laryngeal palsy, and voice therapy may be an option. Surgeons can also change the position of the vocal fold to relieve the symptoms. When breathing is severely affected, a tracheostomy may be required. Alternatively, a stent can be used to open up the airway.
Another treatment used to open up the airway is an endoscopic laser cordectomy. This procedure is an alternative to a tracheostomy and is less invasive. Medical evidence shows this to be an effective treatment for problems with the larynx and vocal cords.
How is Recurrent Laryngeal Nerve Damage Diagnosed?
Doctors can usually diagnose recurrent laryngeal nerve damage by examining the patient and asking about the symptoms. The doctor can also examine the larynx to assess the injury. The doctor will examine both vocal folds to determine if one or both nerves are damaged.
Doctors can also carry out a laryngeal electromyography, which measures electrical currents in the muscles of the larynx. This procedure helps the doctor to determine the severity of the nerve damage. An appropriate course of treatment can then be selected for the nerve injury.
Can the Recurrent Laryngeal Nerve be Repaired?
When the recurrent laryngeal nerve has been damaged it may regenerate by itself and no treatment is required. When the damage is not too severe, the nerve will repair over a period of 8 - 12 weeks. The nerve will grow at a rate of approximately 1mm per day until it has fully regenerated.
If the nerve is cut, it may also repair itself, but surgery will be needed in some cases. Surgeons can carry out one of a number of procedures to repair the damaged nerve.
Repairing the recurrent laryngeal nerve is a complicated surgical procedure that is only performed when necessary. End-to-end suturing can be carried out to join a severed nerve. The two ends of the nerve are stitched back together so that it regrows.
Nerve grafting may also be an option if end-to-end suturing is not possible. A donor nerve is taken from another part of the body and is used to carry out the repair. Grafting is an effective way to repair a nerve. However, the area where the donor nerve was taken from may subsequently become permanently numb.
You now have all the information about the recurrent laryngeal nerve. You know what it does, where it is and understand the importance of its function. You also have information on how the recurrent laryngeal nerve can become injured, the various symptoms and the treatment options available.