Definition
The vocal folds are the parallel folds of tissue that are essential for the formation of sounds and the voice. They are a part of the larynx in the throat. From the outside they are protected and shielded by the externally palpable ring cartilage.
They are covered by mucous membrane and consist mainly of the vocal muscle, the “Musculus vocalis”. The vocal folds in the larynx are attached to various cartilages, which can be moved and adjusted by other laryngeal muscles. These muscles cause the glottis to close or open like a slit, triangle or rhombus.
This results in different tones, which provide the basis for our articulation and speech. The production of sound by the vocal folds is called “phonation”. In the case of a so-called paralysis of the vocal folds, it is mainly the laryngeal muscles that are paralyzed, which allow the glottis to open and move, or the vocal folds are irritated. This can sometimes lead to serious symptoms, such as long-lasting hoarseness or speech problems. This can be caused by irritation of the vocal folds or damage to the nerve that supplies the larynx muscles, the so-called recurrent nerve.
Causes
The underlying cause of vocal fold paralysis is a failure or weakness of the larynx muscles. The reasons for a failure of the musculature can be different. A small nerve branch sends its impulses to almost all laryngeal muscles on its side.
Due to its anatomical position, it is often affected by various diseases of the neck, but especially by medical interventions. Even slight irritation of the nerve, but also a complete severance, leads to weakness and failure of almost all laryngeal muscles. Tumor diseases can also affect the larynx muscles.
Laryngeal and thyroid tumors in particular can affect the sensitive nerve and the sensitive structures in the larynx. More rarely, inflammations, circulatory disorders or viral diseases in the neck area can also cause vocal fold paralysis. Complications after thyroid surgery, for example during struma therapy, are the most common cause of vocal fold paralysis.
During complete or half removal of the thyroid gland, the so-called “recurrent nerve” is damaged or severed in rare cases, often by inexperienced surgeons. During embryological development, the nerve passes completely through the neck and under the large arterial vessels in the upper chest area. It then retracts behind the thyroid gland in the direction of the larynx.
It lies close to the back of the thyroid gland 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 nerve paresis as low as possible. For this purpose, intraoperative probes are used which constantly check the function of the nerve. Immediately after the end of the operation, the larynx is examined by means of a mirror or a small camera or the patient is asked to speak in order to detect potential damage in time.
