Laryngeal nerve palsy
Laryngeal nerve palsy refers to paralysis of the laryngeal nerve, which can significantly impact voice production and breathing. This condition often results from damage to the recurrent laryngeal nerve, commonly due to neck or chest tumors, intrathoracic diseases, or surgical interventions such as thyroidectomy. The recurrent laryngeal nerve controls the movements of the larynx, where the vocal cords are located, and its impairment can lead to symptoms such as hoarseness, voice weakness, or even complete loss of voice. Diagnosis can be challenging and typically involves imaging and specialized examinations to differentiate the cause of vocal fold immobility.
While many cases of laryngeal nerve palsy may resolve spontaneously, treatments include surgical options such as medialization thyroplasty and innovative techniques like nerve transfer and electrical stimulation. In severe instances, where airflow is obstructed, a tracheotomy may be necessary to ensure the patient can breathe. Although there is no specific cure for nerve damage, ongoing advancements in medical treatments offer hope for improved outcomes. Understanding the implications of laryngeal nerve palsy is essential for effective management and support for those affected.
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Subject Terms
Laryngeal nerve palsy
ALSO KNOWN AS: Recurrent laryngeal nerve damage, paralysis of the laryngeal nerve, paralysis of the larynx
RELATED CONDITIONS: Intrathoracic diseases, neurolaryngological lesion
DEFINITION: Laryngeal nerve palsy is the paralysis of the laryngeal nerve.
Risk factors: Damage to the laryngeal nerve can result from neck and chest tumors or intrathoracic diseases such as tumors or aneurysms of the arch of the aorta or the heart's left atrium. Tumors and aneurysms may press on the nerve, causing nerve damage. Damage to the recurrent laryngeal nerve may also occur during surgery on the thyroid gland.
Etiology and the disease process: The vagus nerve is one of twelve cranial nerves. It originates in the brain stem and reaches the large intestine. In the neck, the vagus nerve branches off a paired nerve called the recurrent laryngeal nerve. When the laryngeal nerve separates from the vagus nerve, it reaches into the chest and loops back up to the larynx (voice box). The recurrent laryngeal nerves extend along either side of the trachea (windpipe) between the trachea and the thyroid gland, and they control the movement of the larynx. The larynx is located where the throat divides into the esophagus and the trachea. The voice is produced in the larynx, controlling the airflow into the lungs. It houses the vocal cords and the muscles and ligaments that move the vocal cords. Damage to the laryngeal nerve itself causes laryngeal palsy on the affected side. Less commonly, laryngeal palsy, or paralysis of the larynx, can result from damage to the vagus nerve before the recurrent laryngeal nerve branches off. A damaged laryngeal nerve results in reduced movements of the larynx, causing voice weakness, hoarseness, or the complete loss of voice. Although rare, life-threatening cases may occur if the larynx is paralyzed to the extent that air cannot enter the lungs. Damage can occur to either one or both nerve branches, and paralysis of the laryngeal nerve may be temporary or permanent.
Incidence: Recurrent laryngeal nerve injury, without injury to the superior laryngeal nerve, is the most common traumatic neurolaryngological lesion. Laryngeal nerve palsy is an uncommon side effect of thyroidectomy. It can occur in anywhere from 0 to 38 percent of complete thyroidectomies performed to treat cancer, and less often when only part of the thyroid is removed. Most often patients experience only transient laryngeal nerve palsy and within a few weeks spontaneously recover their normal voice.
Symptoms: The effects of laryngeal nerve damage are flaccidity of the ipsilateral vocal fold, loss of adduction (movement of a limb), severe dysphonia or laryngeal dystonia (involuntary movements of the muscles of the larynx), complete paralytic aphonia (inability to speak), and frequently of food and drink into the trachea.
Screening and diagnosis: Diagnosis and treatment of the immobile or hypomobile vocal fold are challenging. True paralysis and paresis (impaired movement) result from vocal-fold denervation secondary to injury to the laryngeal or vagus nerve. The location of the vocal-fold paralysis and paresis may be unilateral or bilateral, and central or peripheral. Paralysis may involve the recurrent laryngeal nerve, the superior laryngeal nerve, or both. It is important to confirm that the laryngeal impairment is not caused by arytenoid cartilage subluxation (dislocation of small cartilages in the back of the larynx), cricoarytenoid arthritis or ankylosis (stiffness of a joint), neoplasm, or other mechanical causes. The most common diagnostic tools are strobovideolaryngoscopy, endoscopy, radiologic and laboratory studies, and electromyography (EMG).
Treatment and therapy: Once the recurrent laryngeal nerve is damaged, there is no specific treatment to heal it. Common treatments for laryngeal nerve damage are polytetrafluoroethylene (trademark Teflon) injection; medialization thyroplasty, a surgical procedure in which an implant is inserted into the paralyzed vocal cord; arytenoid adduction procedures; or reinnervation by nerve transfer. With time, most cases of recurrent laryngeal palsy improve spontaneously. In the 2020s, novel surgical methods, which involve medializing the paralyzed vocal fold, were developed which improved outcomes and the patient's quality of life. Gene therapies, as well as non-surgical techniques, including new medications, electrical stimulation, neurorrhaphy, nerve transplantation, and neural tissue engineering have also emerged as treatments for laryngeal nerve palsy. In some cases, the larynx may be paralyzed so that air cannot flow past it into the lungs, and an emergency tracheotomy needs to be performed. A tracheotomy is a surgical procedure to make an artificial opening in the trachea, which allows air to bypass the larynx and enter the lungs. If the paralysis is temporary, the tracheotomy hole can be surgically closed. There are no alternative or complementary therapies to heal laryngeal nerve palsy. When loss of speech is permanent, artificial speech devices exist to produce tone.
Prognosis, prevention, and outcomes: Muscle function can be assessed by observing the movements of the structures or by recording the electrical activity of the muscles via electromyography. Although electromyography is an invasive technique, it may be helpful in patients with voice problems of suspected neurological or neuromuscular etiology. Electromyography recordings help differentiate vocal-fold paralysis from arytenoid dislocation. Electromyography is useful for diagnosis, establishing a reliable prognosis and treatment plan, and monitoring muscle denervation and reinnervation. Following acute denervation, the subsequent progression is either chronic denervation or laryngeal nerve regeneration
Bibliography
Araki, Koji, et al. "Gene Therapy for Recurrent Laryngeal Nerve Injury." Genes, vol. 9, no. 7, 2018, doi.org/10.3390/genes9070316. Accessed 27 June 2024.
Calò, Pietro Giorgio, et al. "Role of Intraoperative Neuromonitoring of Recurrent Laryngeal Nerves in the Outcomes of Surgery for Thyroid Cancer." Supp. to International Journal of Surgery, vol. 12.S1, 2014, pp. S213–17.
Crumley, Roger L. “Unilateral Recurrent Laryngeal Nerve Paralysis.” Journal of Voice, vol. 8.1, 1994, pp. 79–83.
Hartl, Dana M., and Daniel F. Brasnu. “Recurrent Laryngeal Nerve Paralysis: Current Concepts and Treatment; Part II—Causes, Diagnosis, and Management.” ENT: Ear, Nose & Throat Journal, vol. 79.12, 2000, pp. 918–28.
Landerholm, Kalle, Anna-Maria Wasner, and Johannes Järhult. "Incidence and Risk Factors for Injuries to the Recurrent Laryngeal Nerve during Neck Surgery in the Moderate-Volume Setting." Langenbeck's Archives of Surgery, vol. 399.4, 2014, pp. 509–15.
Randolph, Gregory W., ed. Surgery of the Thyroid and Parathyroid Glands. 2nd ed., Philadelphia: Saunders, 2013.
Rubin, Adam D., and Robert T. Sataloff. “Vocal Fold Paresis and Paralysis.” Otolaryngologic Clinics of North America, vol. 40.5, 2007, pp. 1109–31.
Tian, Hedi, et al. "A Narrative Review of Current Therapies in Unilateral Recurrent Laryngeal Nerve Injury Caused by Thyroid Surgery." Gland Surgery, vol. 11, no. 1, 2022, pp. 270-278, doi.org/10.21037/gs-21-708. Accessed 27 June 2024.
Woodson, G. “Evolving Concepts of Laryngeal Paralysis.” Journal of Laryngology & Otology, vol. 122.5, 2008, pp. 437–41.
Ysunza, Antonio, et al. “The Role of Laryngeal Electromyography in the Diagnosis of Vocal Fold Immobility in Children.” International Journal of Pediatric Otorhinolaryngology, vol. 71.6, 2007, pp. 949–58.
Zakaria, Hazem M., et al. "Recurrent Laryngeal Nerve Injury in Thyroid Surgery." Oman Medical Journal, vol. 26, no. 1, 2011, pp. 34-38, doi.org/10.5001/omj.2011.09. Accessed 27 June 2024.