The term vocal cord palsy describes a paresis, the muscles that move the vocal folds in the larynx. The result is that the paired vocal folds are restricted in their movement and thus the speech and possibly also the breathing are difficult. In the larynx, there are a number of small muscles involved in the movement and tension of the vocal folds. When the nerves that control these muscles become damaged, vocal cord paresis occurs. This can occur unilaterally and also bilaterally, whereby the bilateral vocal cord paresis represents an emergency due to the relocation of the respiratory tract.
The causes of vocal cord paresis can be very diverse. All have in common that as a result, the nervous supply to the muscles involved is disturbed. The most common causes of direct nerve damage are vocal cord paresis. The affected nerve is the recurrent laryngeal nerve (short: recurrent nerve), which is present on both sides and controls almost all of the laryngeal muscles on one side. In surgical interventions on the thyroid or carotid artery, this nerve can be injured because of the close anatomical relationships, resulting in a so-called recurrent nerve palsy. Therefore, this complication is always pointed out before such operations.
Also, other interventions on the neck such as for the treatment of tumors on the larynx or in the esophagus can damage the nerves. The tumor itself can also cause vocal cord paresis. Another cause of vocal cord palsy is an outflow of blood vessels called the aneurysm . Located on the carotid artery or the aorta, these can irritate the recurrent nerve. In addition, possible causes of vocal cord paresis are any injuries or trauma to the neck. In addition, in the context of a stroke brain areas may be affected, which control the larynx. In rare cases inflammation and viral diseases have been observed as causes of vocal cord palsy
A vocal cord palsy causes a number of typical symptoms. For the perfect formation of the language, the complete closing of the vocal folds is necessary, which is not possible with the vocal fold paresis. The main symptom is hoarseness, which occurs in one-sided vocal fold paralysis, which is more common than bilateral. One side of the vocal folds works normally, while the other one is paralyzed and does not resonate properly in voice formation. This causes hoarseness, which can be both mild and very pronounced.
In bilateral vocal cord paresis, speaking is actually not possible. The bigger problem, on the other hand, is that the respiratory tract may be severely restricted or even misplaced due to the paralysis of both sides, which can lead to massive respiratory distress.
For the diagnosis of vocal cord paresis a detailed questioning of the patient is often sufficient. Above all, previous surgeries on the neck and the sometimes very pronounced hoarseness are interesting. The ENT specialist can then perform a laryngoscope scan to assess the movement and position of the vocal folds. To rule out laryngeal cancer, computed tomography (CT) or magnetic resonance imaging (MRI) may be useful.
A term from the diagnosis of vocal cord palsy, which often falls, is the so-called paramedian position. The term paramedian position describes the position of the vocal cords in the context of a vocal cord paresis, in which the end of the vocal cords is not completely possible and one side comes to lie slightly next to (para) the middle (median). This is a clear indication of damage to the recurrent laryngeal nerve. The paramedian position can be seen in laryngoscopy and is important in the differential diagnosis of vocal cord paresis, since other vocal fold positions such as mid-medial or lateral (lateral) orientation indicate other disorders.
A vocal cord palsy can occur both on both sides or one-sided. On the left, it occurs when an operation on the left side of the neck has been made or a tumor infiltrates the left recurrent nerve. A special feature of vocal cord palsy on the left is that the nerve on the left has a slightly different course than on the right side. He pulls here deeper down to below the aortic arch, so that on this side and lacerations or cracks of the aortic arch, such as an aortic aneurysm can cause a left-sided vocal cord palsy. Likewise, processes in the lungs can affect the nerves on the left side.
On the right side, the course of the recurrent laryngeal nerve does not extend all the way into the thorax, so the likelihood of damage to the nerve is slightly lower than on the left side. The aorta and lungs are not in contact with the nerve on the right. Of course, all processes, procedures and injuries to the neck can affect the nerves. If there is a unilateral vocal cord palsy, the symptoms are largely independent of whether the damage is left or right.
If there is vocal cord palsy, the therapy is initially dependent on the cause. The goal is always to bring the vocal folds back together as close as possible. For example, if compression of the recurrent nerve by a tumor or aneurysm is the cause of vocal cord paresis, the therapy consists of removing these obstructive processes. Often the vocal cord palsy will recover over time.
If the nerve has been injured during an intervention or if there is irreversible paralysis, further treatment measures must be initiated. A major role is played by the speech therapy, which is used by almost every patient with vocal cord palsy. Special exercises improve the language here. If this too is unsuccessful, an invasive therapy may be useful. You can inject the affected side of the vocal cord with special substances to make them move closer to the center. Furthermore, there are surgical techniques in which with the aid of a punch ( Thyhasoplasty according to Isshik i) one side is pushed further towards the middle or pulled with sutures ( arytenoid adduction ) in this direction. These methods are useful for unilateral vocal cord paresis.
The rare bilateral paralysis of the vocal folds may require a tracheotomy in an emergency to avoid asphyxia, which may require enlargement of the vocal folds.
Speech therapy is an important pillar of treatment in most cases of vocal cord palsy. With the help of special exercises, the patient can train his vocal folds under professional guidance by the speech therapist to the extent that a clear improvement of the voice up to the complete recovery is possible. Especially if the nerve has not been completely severed, the speech therapy in vocal cord paresis is very promising. The goals of speech therapy are to stimulate the muscles in the larynx and prevent atrophy, as well as to train the healthy side of the vocal folds above normal levels so that they extend over the middle to the paralyzed side. Thus, the conclusion of the glottis can generate a normal language
A blanket statement on the duration of vocal cord paresis is difficult to make, as it depends on the cause, extent of the injury and the type of treatment. The vocal cord palsy treated by speech therapy should be significantly improved within one to one and a half years. If a restriction has been removed, the duration may only be a few months if the nerve has not been severed. In some cases, however, there may be some hoarseness and language restriction throughout life.