Anatomy of the Condition:
The vocal folds are located within the larynx or voice box.  They are structures which open for breathing, and come together during swallowing, and vibrate as air passes between them during speaking or singing.  They are made up of fine layers, with a soft outer cover, a stiffer ligament below this, and a muscle called the thyroarytenoid muscle located deep to the ligament.  The thyroarytenoid muscle makes up the bulk of the vocal fold.

Paralysis of the vocal folds causes an inability to move the muscles of the vocal cords and can impact all three functions of the larynx.  When one vocal fold is paralyzed, (unilateral vocal fold paralysis), voice and sometimes swallowing are impaired.  When both vocal folds are paralyzed, (bilateral vocal fold paralysis),  the airway and breathing are severely compromised.

Causes or Contributing Factors
Vocal fold paralysis can be caused by surgical injury, trauma, tumors, or viral infections. 

Symptoms:

Symptoms of unilateral vocal fold paralysis include:

• A soft, breathy voice (which is usually an indication of one-sided paralysis). 
• Difficulty with vocal projection
• Impairment of the ability to swallow, with aspiration in the air passage or lungs.  Rarely, this can lead to pneumonia.

Symptoms of bilateral vocal fold paralysis include:

• Difficulty breathing from airway obstruction
• Stridor, a condition that closes the airway when breathing and causes noises in the throat and changes in the shape of the chest as the body struggles to breathe.

Diagnosis:
The physician will ask the patient about symptoms and medical history, followed by a thorough head and neck examination. The examination likely will involve several members of the voice team to test for vocal quality, efficiency, and proper speaking technique.

Laryngeal videostroboscopy may be required.  This is a procedure using a flexible and/or rigid endoscope coupled to a video monitor and a stroboscopic light source to allow for detailed visual evaluation of laryngeal function and vibration.

Microlaryngoscopy may be required.  It is a procedure conducted under general anesthesia which allows the physician to examine the vocal folds of the larynx with magnification tools. 

Other tests to confirm diagnosis can include a CT scan or an MRI, which provide high resolution images of the structures of the neck and larynx
 
Treatment for Unilateral Vocal Fold Paralysis:
After vocal fold paralysis occurs, it is often not clear whether movement will recover for 9 to 12 months.  In this period of time, speaking and swallowing therapy can be helpful to improve voice and swallowing function while waiting for vocal fold motion to return. 

Often times, vocal fold movement does not return, and then patients may need to undergo surgery to improve their voice and swallowing.  Surgical treatment options include thyroplasty, injection laryngoplasty, or laryngeal reinnervation.  Thyroplasty and injection laryngoplasty attempt to move the paralyzed vocal fold toward the mobile vocal fold to improve voice and swallowing.  Laryngeal reinnervation is a surgical procedure to restore nerve supply to the paralyzed vocal fold in order to improve its tone and bulk.

Treatment for Bilateral Vocal Fold Paralysis:
Because of airway obstruction, bilateral vocal fold paralysis is a more serious problem than unilateral vocal fold paralysis.  Often times a life saving tracheotomy is required to provide a breathing passage.

After a safe airway is created, there are several surgical procedures which attempt to improve the airway while minimizing affect on the voice.  These include posterior vocal cordotomy and endoscopic laser arytenoidectomy.  Posterior vocal cordotomy is an endoscopic procedure in which one or both of the vocal folds are divided to improve the airway.  Another minimally invasive surgical option is endoscopic laser arytenoidectomy. With this procedure, a laser is used to remove one of the cartilages which makes up the vocal fold to widen the air passage and improve breathing. Some patients benefit from laryngeal Botox therapy.