Disorders of innervation of the larynx

The larynx is innervated by 2 branches of the vagus nerve. They are:


 * superior laryngeal nerve and
 * recurrent laryngeal nerve.

Paresis of n. laryngeus superior
The superior laryngeal nerve branches into ramus internus and ramus externus.


 * Ramus internus provides sensory innervation of the supraglottic part of the larynx.
 * The ramus externus motorically innervates the cricothyroideus muscle.

Paresis of the superior laryngeal nerve can occur:
 * by damage to the nuclei of the vagus nerve;
 * damage to the own vagus nerve above the distance of the superior laryngeal nerve - tumor, trauma, neurological disease, skull base surgery;
 * damage to the superior laryngeal nerve - larynx surgery, pharynx surgery (rarely thyroid surgery).

As follows from the function of the superior laryngeal nerve, paresis of this nerve will lead to anesthesia of the supraglottic part of the larynx and paresis of the cricothyroideus muscle.
 * Anesthesia of the supraglottic part of the larynx → dysphagia, food falling into the airways with the risk of aspiration.
 * Paresis of the cricothyroid muscle → limitation of vocal range.

Therapy: swallowing rehabilitation, phoniatric care.

Paresis of n. laryngeus recurrens
Nervus laryngeus recurrens provides sensory innervation of the subglottic part of the larynx and motorically all muscles of the larynx except the cricothyroideus muscle.

Paresis of n. laryngeus recurrens can occur:
 * by damage to the nuclei of the vagus nerve;
 * damage to the vagus nerve itself above the recurrent laryngeal nerve - tumor, trauma, neurological disease, skull base surgery;
 * damage to recurrent laryngeal nerve - neck surgery, upper mediastinal surgery and above all thyroid surgery.

Unilateral paresis

 * Unilateral paresis is manifested by a phonation disorder. Inspiratory dyspnea is not present.
 * The vocal cord becomes immobile, it is fixed in the paramedian position.
 * Therapy: phoniatric care - in case of failure, surgery (thyreoplasty) comes next.

Bilateral paresis

 * Bilateral paresis leads to airway stenosis in the glottis region.
 * Clinically, it manifests as dysphonia, dysphagia, and inspiratory dyspnea with inspiratory stridor.
 * The vocal cords are immobile, fixed in a paramedian position.
 * Therapy: provision of airways, widening of the respiratory slit (laterofixation of the vocal cords, arytenoidectomy, chordectomy).