Vocal cord paralysis

definition

The vocal folds are the parallel folds of tissue that are significantly involved in the formation of sounds and the voice. They are part of the larynx in the throat. From the outside they are protected and shielded by the externally palpable cricoid cartilage. They are covered by a mucous membrane and mostly consist of the vocal muscle, the "vocalis muscle".

The vocal folds in the larynx are attached to various cartilages that can be moved and adjusted by other larynx muscles. These muscles cause the glottis to close or open like a crack, triangle, or diamond. This results in different tones, which provide the basis for our articulation and language. The sound generated by the vocal folds is called "phonation".

In so-called paralysis of the vocal folds, the larynx muscles, which allow the glottis to open and move the vocal folds, are paralyzed, or the vocal folds are irritated.

This can sometimes lead to serious symptoms, such as prolonged hoarseness or difficulty speaking.

The cause can be irritation of the vocal folds or damage to the supplying nerve, the so-called recurring nerve, which supplies the larynx muscles.

causes

The underlying cause of vocal cord paralysis is failure or weakness of the larynx muscles. The reasons for muscle failure can be different. A small branch of nerve sends its impulses to almost all of the larynx muscles on its side. Due to its anatomical position, it is often impaired in various diseases of the neck, but above all in medical interventions. Even slight irritation of the nerve, but also a complete severing, lead to weakness and failure of almost all larynx muscles.
Tumor diseases can also affect the larynx muscles. Larynx and thyroid tumors in particular can affect the sensitive nerve and the sensitive structures in the larynx.
More rarely, inflammation, circulatory disorders or viral diseases in the throat area can also cause paralysis of the vocal cords.

Read more about inflammation of the vocal cords, signs of thyroid cancer, and vocal cord cancer.

Vocal cord paralysis after thyroid surgery

Complications after operations on the thyroid gland, such as goiter therapy, are the most common cause of vocal cord paralysis. In the context of complete or half-distance removal of the thyroid gland, in rare cases, often with inexperienced surgeons, the so-called "recurrent nerve" is damaged or severed. As a result of the embryological development, the nerve passes completely through the neck and under the large arterial vessels in the upper chest area. Then it pulls back behind the thyroid towards the larynx. It lies close to the back of the thyroid on both sides. This exposed position of the thin nerve makes it very susceptible to any injury.
Nowadays, attempts are made to keep the risk of recurrent palsy as low as possible. For this purpose, probes are used intraoperatively, which constantly check the function of the nerve. Immediately after the end of the operation, the larynx is viewed using a mirror or a small camera, or the patient is asked to speak in order to identify potential damage in good time.

Read more about recurrent palsy.

Symptoms

A typical symptom of vocal cord paralysis on one side is hoarseness. When one side of the larynx muscles fails, the phonation in the larynx can no longer proceed properly and a permanent hoarseness develops. The vibration and tone formation are disturbed, depending on how pronounced the paralysis of the larynx muscles is. Normal speaking therefore also requires more air consumption.
If both sides are affected by vocal fold paralysis, the glottis can no longer open by itself and acute shortness of breath occurs. The air can no longer escape through the closed vocal folds and therefore the patient has to be ventilated by intensive care if it fails completely.

Read more about hoarseness here.

Right or left vocal cord paralysis

The anatomy of the recurrent nerves differs on both sides. Just like the large arterial vessels that branch off from the aorta towards the neck, the larynx nerves also differ on both sides.

On the right side, the fine recurrent nerve branches off from the main nerve and loops around the main artery of the neck and arm at the level of the collarbone. On the left, on the other hand, the nerve pulls significantly deeper into the chest and only winds around the aorta itself just above the heart. Its course is significantly longer than on the right side and thus the nerve is more prone to damage in its long course. As a result, the left side is affected by vocal fold paralysis almost twice as often as the right.

Unilateral Vocal cord paralysis is evident more often as bilateral. A hoarseness is the typical consequence of one-sided lack of vibrations in the glottis. It does arise no shortness of breath, however, more air is used for normal speaking.

Vocal cord paralysis on both sides

Bilateral vocal cord paralysis is rare. If it occurs, it leads to serious symptoms and a need for intensive care. In the normal relaxed state, the glottis is closed. In particular, the muscles that open the glottis wide are affected in vocal cord paralysis. As a result, the larynx cannot be opened and there is shortness of breath, severe hoarseness and a hissing sound when trying to breathe.
In the case of severe, acute shortness of breath, the patient must be supported by artificial respiration if necessary. If there is no improvement or prospect of a cure, an operation can help to permanently dilate the glottis. Sometimes the artificial access has to be continuously ventilated. In particular, infections of the lungs and respiratory tract are a frequent consequence, as mucus and germs can no longer be reliably coughed up.

diagnosis

An important part of the diagnosis of vocal cord paralysis is based on the patient's medical history and language skills. A typical permanent hoarseness is already groundbreaking for the diagnosis. The larynx can then be viewed by the ENT doctor using either a larynx mirror that the doctor holds in the patient's throat or an endoscopy of the larynx. In this so-called "laryngoscopy", a camera with light is pushed into the patient's larynx and the glottis is viewed on a display. Pareses on one side are particularly noticeable when comparing the left and right sides.

In order to secure the diagnosis, an "electromyography", ie a check of the muscle ability through electrical stimulation, can be carried out. If no thyroid surgery has been performed beforehand, the cause of the vocal cord paralysis should be determined. A CT or MRI examination of the neck and chest can show any abnormalities well.

treatment

Treatment depends on the extent of the damage. If the nerve has been completely severed, for example as part of a thyroid operation, there is no prospect of improvement through exercise. Surgical intervention can help align the vocal folds so that symptoms are minimal. In the case of bilateral vocal cord paralysis, surgical intervention can also widen the glottis so that there is no acute shortness of breath.
If the nerve of the larynx is only irritated and restricted in its function, its function can be restored through exercise. Certain speaking exercises can help regain range of motion.

Exercises

In the event of irritation and partial failure of the larynx muscles, there is a good chance of regaining the original functions. The Exercises aim to produce as many different sounds as possible. As with normal muscle training to build up, the larynx muscles must also be used equally.

To ensure successful rehabilitation, one should Speech therapist to be visited. By constantly practicing different vowels with increased emphasis, a large part of the language ability can often be regained over time.

Nowadays come too Electrostimulation procedure for use. The contraction can be triggered by targeted stimulation of certain muscles. Electrostimulation to strengthen the muscles has the same effect as conscious tension through phonation exercises.

Cure / prognosis

The possibility of a complete cure from vocal cord paralysis depends on the cause of the paralysis. In rare cases, especially in accidents or after operations, the nerve is responsible completely severed or so badly damaged that paralysis not curable is.

In many cases, however, the nerve is merely irritated. If there is a tumor that is pressing on the nerve, it must Fixed the cause become. If the nerve has a residual function and is not severed, the muscles can often divide through subsequent therapy recover.

Nerve tissue is very sensitive and is still difficult to treat today. However, the more severely the nerve is damaged, the less likely it is to regain much of its function.