Vocal cord paresis

Recurrent laryngeal nerve palsy is the medical term for an injury to the recurrent laryngeal nerve Rekurrensnervs, who heads the movement instructions for the internal laryngeal muscles from the brain to the larynx and thus is important for phonation and respiration.

Anatomy and Introduction

The recurrent laryngeal nerve gets its name because of its anatomical course: runs he rises in the neck from the vagus nerve (10th cranial nerve), extends right up to the border of the rib cage and left up into the chest, then turns around an artery and the neck to the larynx back (Latin recurrere ). Its function is the transmission of nerve signals to the muscles that allow regulation of vocal fold position and voltage and thus the voice training, but also the transmission of nerve signals from the mucosa of the larynx to the brain in particular.

A unilateral damage to the nerve manifests itself in a hoarseness as a result of deteriorating mobility of the vocal cord / vocal fold. If such damage on both sides, so the vocal folds impede the flow of air and the patient suffers from a severe respiratory activity.

As the nerve passes through the thyroid gland in more immediate neighborhood, the most common injury in thyroid or neck surgery can be observed. To avoid damage, the nerve is selectively retrieved during these operations. Better yet is a neuro-monitoring, in which even the slightest irritation of the nerve can be visualized by the measurement of electrical muscle impulses.

Due to the high risk potential for neck surgery a study of the vocal fold mobility is performed by an ENT doctor or Phoniater regularly after surgery.

Parathyroid surgery, there are a variety of possible causes such as cardiac surgery, disc surgery of the cervical spine, tumors of the thyroid, lung upper lobe, esophagus, or other organs and nerve damage following viral infections.

Definition / classification

Often the term is used synonymously with recurrent nerve paralysis by the doctor for a partial or complete shutdown of one or both vocal folds. Medical point of view this can be misleading as well as scarring of the larynx after long- term ventilation, injuries ( dislocations ) and inflammation of the arytenoid cartilage joint ( rheumatism ), but also may cause the ingrowth of tumor in the vocal fold to a standstill. Therefore, further investigations by the otolaryngologist or Phoniater must be made before one can speak of a recurrent laryngeal nerve palsy. Precisely because, for example, provides further ramifications in the case of tumors, each ( unclear ) vocal fold arrest should be clarified.

In the language of the recurrent laryngeal nerve palsy is often referred to as vocal cord or vocal cord paralysis.

A vocal cord arrest may be unilateral or bilateral. The paralyzed vocal fold may rest in different positions. You can centrally (median ), adjacent to the center ( midline, most commonly occurring ) or more rarely on the side ( intermediate or lateral) are available.

The paralysis of the vocal cords may like limp or, in the majority of cases, firm (ie with preserved - muscle tension ) to be. Many are initially flaccid paralysis and taut over time. The cause of a random regrowth of the nerve from the damage point is considered in the inner muscles of the larynx. This usually leads to a tension, but not to a return of vocal fold movement, which is generally described as synkinesis.

Symptoms

The main symptoms are different for one - and two-sided paresis.

The unilateral vocal cord paralysis caused by the incomplete closure of the vocal folds during phonation hoarseness. This can be seen in a low, breathy, not increases to a firm voice. In addition, there is a shortness of breath when speaking (because the phonation air escapes unused ). Breathing itself is usually only due to an unfavorable position of the paralyzed vocal cord affected since the opening of the other, the healthy vocal fold is sufficiently at rest and during light load. Although the origin of nerve ( vagus nerve ) is affected, incorrect swallowing and swallowing problems may be added.

In bilateral vocal cord paralysis, the remaining glottis during inhalation and exhalation is extremely narrow. In addition, the feeble vocal folds are sucked in by the breath power even further ( Bernoulli effect ). The flow of breathing air is often significantly impeded. This causes especially under load, for respiratory infections and, not infrequently, in sleep apnea and be perceived breath sounds at inhalation and exhalation ( stridor ). Patients often snore very loud, some with dangerous interruptions in breathing ( sleep apnea ). In extreme cases the system of a tracheostomy tube is required for two-sided paralysis. These vital action is felt by the patient as a social stigma, of which they suffer additionally. Due to the reduced air exchange of the lungs with the environment have affected both sides also having problems with shortness of breath. For additional diseases, such as influenza, this can cause a feeling of breathlessness especially when both sides concerned. Also, can cause respiratory distress also laugh, or an emotional situation. Affected usually suffer from poor sleep quality and in some cases require naps during the day. Due to the constant shortage of sufficient air also disorders of the cardiovascular system may occur (eg high blood pressure) in a row. Rare muscle pain can be observed, probably also related to the lack of breathing. It also results in sharp decline in physical performance, especially with two-sided paresis. Very often sufferers are severely limited in everyday life. Most patients with a bilateral vocal cord paralysis have long term or even permanently incapacitated.

Causes

A vocal cord paralysis can have many causes. Not always the cause can be demonstrated. Such idiopathic paresis often affect the entire originating nerve ( vagus nerve ). It is assumed that undetectable viral infection of the nerve or reactivation of existing viruses (usually zoster / chicken pox virus). Paralysis of the nerve of origin can also result from stroke, ie of bleeding or vascular occlusions in the brain to be. Malignant tumors such as thyroid cancer or settlements of malignant tumors ( metastases) can the recurrent laryngeal nerve or the vagus nerve damage in the course and a paresis cause. Tumors can also occur directly in the brain and thus cause damage to the area of ​​origin of the vagus nerve. Injuries of the nerve also occur through operations on the thyroid gland, spine, neck vessels, heart and lungs. Rarely has a vocal cord paralysis is by direct injury to the neck or by pressure on the nerves, for example, through a breathing tube caused.

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Diagnosis

The standards for evaluation of vocal fold arrest are not uniform. Important notes on possible causes arising from the exact detection of medical history.

General rule is that when a nerve injury of unknown cause a tumor in the course of the vocal cord nerves should be excluded. This is done by a thorough ENT endoscopy and additionally by medical imaging techniques ( ultrasound examination of the neck, computed tomography ( CT) of the chest, especially in left-sided paralysis and magnetic resonance imaging (MRI ) of the neck, including skull base and possibly the brain). When a tumor is suspected in an anesthesia endoscopy, the shares of the pharynx ( the hypopharynx ) and the upper esophagus are presented and the passive mobility of the vocal cord arytenoid cartilage ( arytenoid ) tested.

A voice diagnostics is used to assess the quality of voice and vocal performance. The voting result is important for the planning and successful assessment of a possible voice therapy ( speech therapy ).

For incomplete or only partially healed paralysis can be produced by a stroboscopic laryngeal examination a kind of slow motion, which gives information about voltage and fine mobility of the vocal folds during phonation. Stroboscopy and voice findings are important for the development of an individual treatment plan to improve the voice.

With breath tests (spirometry, body plethysmography ) the restriction of the respiratory air passage is measured through the larynx, especially in patients with bilateral paresis.

An electromyography of the laryngeal muscles ( laryngeal EMG), in which the electrical activity of the laryngeal muscles is derived via thin needle electrode, the precise distinction between a nerve damage or other causes of movement disorder of the vocal fold and the containment of the injury site in the nerve course serves. The Laryngeal EMG can give to a certain extent a prediction on the course of recurrent laryngeal nerve palsy. Patients with a poor chance of recovery can be detected early in the laryngeal EMG. Unfortunately, this particular study is not yet universally in the treatment centers.

All test results must be seen by the attending physician is always in connection and an individual diagnosis and treatment plan can be created for each patient.

Epidemiology

Scientific opinions on this topic go from about ten thousand unilateral, bilateral vocal cord paralysis and one thousand per year in the German-speaking countries. However, detailed information in the scientific literature are very sparse and not always clear.

Treatment

Treatment depends on the cause and the prevailing symptoms.

If an underlying disease requiring treatment before as the cause of the vocal fold arrest or the recurrent laryngeal nerve palsy, such as a tumor, then this should be treated accordingly. If symptoms, such as a rapid recovery of unilateral paresis, are low, a specific treatment is not always necessary. After the appropriate diagnosis of ENT doctor or Phoniater will control the rest.

In unilateral vocal fold paresis with poor voice, the treatment aims to vocal enhancement. The preferred form of therapy in this case the vocal exercise treatment ( speech therapy ). Through specific exercises, it is possible the therapist to improve the closing of the vocal folds during phonation. A complete possible contact between the two vocal folds to each other is important for efficient and harmonic sequence in the vocalization. If this can not be achieved in the course of logotherapy, further measures are needed. These have the aim of the paralyzed vocal fold closer to the center line ( medialization ) and thus to shift to the healthy side. In many cases, the medialization be achieved by injections of the vocal folds ( vocal fold ). There are several different substances of different consistency and duration in the tissue, so that for each case the appropriate substance can be selected. Stimmlippenaugmentationen can be made both under local anesthesia and in a short general anesthesia.

Surgical procedures for the medialization of the paralyzed vocal fold then come into consideration when a sole augmentation is not sufficient. Essentially, two methods are used. The medialization of the vocal fold from the outside by inserting a " punch " between vocal fold and the thyroid cartilage ( Thyreoplastik type I Isshiki ) with autologous cartilage, silicone, titanium clips or Goretexstreifen ) and the inversion of the vocal fold arytenoid cartilage ( Arytänoidadduktion ) by special reins seams. Both methods can also be combined.

In the bilateral vocal cord paralysis is to achieve a sufficient breathing in the foreground. In an emergency, the system of a tracheotomy ( tracheostomy ) may be needed.

For permanent restriction of breathing during exercise an operational extension of the glottis ( glottis ) is sought. Since such an intervention threatens the voice quality and usually can not be reversed, Glottiserweiterungen should be done only if a motion recurrence of the larynx by healing at least one vocal cord nerve is no longer expected. Due to the slow regrowth of the nerve healing probation of at least 6 to 12 months is recommended in general. By a laryngeal EMG prognosis could previously estimated, and thus, in some cases, the waiting time can be shortened to a glottis.

A distinction ( lateralization according to Lichtenberger ) and various permanent method of glottis between a partially reversed to machendem method for Seitverlagerung of vocal fold using a special seam. These will (very rarely both) cut the vocal cords with the laser beam and removes parts of the vocal fold and the arytenoid cartilage one of the. This expansion of the airway occurs almost always in some degradation of the voice, because no complete vocal fold closing is possible. The more the expansion is carried out, the weaker is the voice. Therefore, it is necessary to find the best possible compromise between improving breathing and receipt of voice.

To meet the requirement, get the voice and yet to improve breathing, an at least partial restoration of the vocal fold mobility is required. A look at the research suggests that future dynamic treatment approaches are possible.

Paresis could be treated in the future with a so-called laryngeal pacemaker. This new implant has already been used in a first-in -human study with several patients. First results show that the method is safe, and brought the first indications that the method allows an improvement of breathing without compromising voice quality.