Vocal fold paralysis
Vocal fold paralysis (also known as vocal cord paralysis) is a voice disorder that occurs when one or both of the vocal folds don’t open or close properly. Single vocal fold paralysis is a common disorder. Paralysis of both vocal folds is rare and can be life threatening.
The vocal folds are two elastic bands of muscle tissue located in the larynx (voice box) directly above the trachea (windpipe). When you breathe, your vocal folds remain apart and when you swallow, they are tightly closed. When you use your voice, however, air from the lungs causes your vocal folds to vibrate between open and closed positions.
If you have vocal fold paralysis, the paralyzed fold or folds may remain open, leaving the air passages and lungs unprotected. You could have difficulty swallowing or food or liquids could accidentally enter the trachea and lungs, causing serious health problems.
Vocal fold paralysis can result from a lesion or damage to either the vagus or recurrent laryngeal nerve and usually results in breathy dysphonia and effortful voicing.
Common causes of unilateral recurrent laryngeal nerve involvement include thyroid surgery (and occasionally thyroid cancer), other neck surgery (anterior discectomy and carotid endarterectomy), and mediastinal or apical involvement by lung cancer.
Skull base tumors often involve or abut upon lower cranial nerves and may affect the vagus nerve directly, or the vagus nerve may be damaged during surgical management of the lesion. While iatrogenic injury is the most common cause of unilateral vocal fold paralysis, the second most common cause is idiopathic.
However, before deciding whether the paralysis is due to iatrogenic injury or is idiopathic, the clinician must exclude other causes, such as malignancy. In the absence of other cranial neuropathies, a CT scan with contrast from the skull base to the aorto-pulmonary window (the span of the recurrent laryngeal nerve) should be performed. If other cranial nerve deficits or high vagal weakness with palate paralysis is noted, an MRI scan of the brain and brainstem is warranted.
Causes of bilateral fold paralysis include thyroid surgery, esophageal cancer, and ventricular shunt malfunction. Unilateral or bilateral fold immobility may also be seen in cricoarytenoid arthritis secondary to advanced rheumatoid arthritis, intubation injuries, glottic and subglottic stenosis, and, of course, laryngeal cancer.
Symptoms of vocal fold paralysis include changes in the voice, such as hoarseness or a breathy voice; difficulties with breathing, such as shortness of breath or noisy breathing; and swallowing problems, such as choking or coughing when you eat because food is accidentally entering the windpipe instead of the esophagus (the muscular tube that connects the throat to the stomach). Changes in voice quality, such as loss of volume or pitch, also may occur. Damage to both vocal folds, although rare, usually causes serious problems with breathing.
The goal of intervention is the creation of a safe airway with minimal reduction in voice quality and airway protection from aspiration. A number of fold lateralization procedures for bilateral paralysis have been advocated as a means of removing the tracheotomy tube
Unilateral vocal fold paralysis is occasionally temporary and may take over a year to resolve spontaneously. Surgical management of persistent or irrecoverable symptomatic unilateral vocal fold paralysis has evolved over the last several decades. The primary goal is medialization of the paralyzed fold in order to create a stable platform for vocal fold vibration.
Additional goals include advancing diet and improving pulmonary toilet by facilitating cough. Success has been reported for years with injection laryngoplasty using Teflon, Gelfoam, fat, and collagen. Teflon is the only permanent injectable material, but its use is discouraged because of granuloma formation within the vocal folds of some patients. Temporary injectable materials, such as collagen or fat, provide excellent temporary restoration of voice and can be placed under local or general anesthesia.
Once the paralysis is determined to be permanent, formal medialization thyroplasty may be performed by creating a small window in the thyroid cartilage and placing an implant between the thyroarytenoid muscle and inner table of the thyroid cartilage. This procedure moves the vocal fold medially and creates a stable platform for bilateral, symmetric mucosal vibration.