Vocal Cord Paralysis Causes and Diagnosis

Vocal cord paralysis is a common voice disorder occurring with either one (unilateral) or both (bilateral) vocal cords. This occurs when your vocal cord(s) do not open and close appropriately, in a frozen or paralyzed state, which can leave your airway unprotected. The left and right vocal cords lie directly above the trachea within the larynx or voice box. Vocal cord paresis is similar to vocal cord paralysis except rather than being paralyzed, the vocal cords still work a little, but not very well.

The majority of cases are unilateral with the left vocal cord being affected twice as often as the right. Females are also 33% more likely than men to have vocal cord paralysis. Damage to major nerves supplying vocal cords (laryngeal nerve and vagus nerve) and/or certain parts of the brain can be related to the cause of paralysis. Depending upon the nature and severity of the paralysis, symptoms of vocal cord paralysis can range from mild to life-threatening. Bilateral vocal cord paralysis is rare but life-threatening.

Close-up of woman holding her throat
Rubberball / Nicole Hill / Getty Images


There are many potential causes for vocal cord paralysis including:

  • Tumors (cancerous and non-cancerous)
  • Traumatic injury
  • Neurotoxins (exposure to harmful substances such as lead, arsenic, or mercury)
  • Idiopathic (unknown cause; believed to be most likely related to viral neuronitis [labyrinthitis])
  • Viral infection
  • Neurodegenerative and neuromuscular disease

Tumors at the base of the skull, neck, and chest are associated with vocal cord paralysis. The paralysis occurs because of compression of nerves that control the vocal cords. Common tumor sites include the thyroid, esophagus, and chest. Traumas related to vocal cord paralysis include accidental damage to nerves during neck or chest surgery, blunt or penetrating neck/chest trauma, and rarely due to endotracheal intubation (the insertion of a breathing tube through the mouth and into the lungs).


Symptoms of unilateral vocal cord paralysis include:

  • Hoarseness
  • Breathy voice (others hear sounds of breathing while you are talking)
  • Change in vocal quality – loss of loudness or pitch

Symptoms of bilateral vocal cord paralysis include:

  • Dyspnea (difficulty breathing)
  • stridor (a high pitched sound when breathing in)
  • Difficulty swallowing – may choke or cough while eating

In bilateral vocal cord paralysis, both vocal cords are unable to open and close appropriately and therefore do not open when breathing in and close when swallowing. Because the airway is partially blocked when inhaling, stridor can occur due to the turbulent airflow through the vocal cords. Choking and coughing may occur while eating because the airway is unprotected while swallowing and some food or liquid may pass through the vocal cords into the airway. This is also known as aspiration and can cause pneumonia to occur.


In order to diagnose vocal cord paralysis, an otolaryngologist (ENT) should be consulted. Be prepared to answer a series of questions about possible environmental exposure to neurotoxins, previous surgeries, recent traumas, and other symptoms that you have been experiencing.

An endoscope will also be used to allow the physician to visualize your vocal cords. A speech-language pathologist may also be useful in diagnosing vocal cord paralysis.

While the use of the endoscope can be used to diagnose vocal cord paralysis, other tests may need to be performed in order to identify the cause of paralysis. Other exams that may need to be performed include:


Once the cause of the vocal cord paralysis is identified treatment can begin. In the case of a tumor surgery may be needed to remove or reduce the size of it. If the cause is reversible, steps should be taken to correct the problem. In many cases, the first line of treatment is speech therapy. Surgery is not always necessary and in some cases of vocal cord paralysis will correct themselves over the course of a year. Therefore many physicians will counsel to delay surgical procedures until a year has passed to see if the paralysis will resolve on its own.

Treatments are also available to help improve the voice if the quality does not return on its own or with speech therapy. Three available treatments for unilateral vocal cord paralysis include augmentation, surgical repositioning, and reinnervation of the vocal cord.

  1. Augmentation or bulking up the vocal cord can be performed by an otolaryngologist. This is done by inserting collagen, fat, or other kinds of tissue graft into the paralyzed vocal cord. By making the affected vocal cord bigger it will be closer to the unaffected vocal cord and the vibration between the two cords may improve the quality of the voice.
  2. Surgical repositioning of the vocal cord works in a similar method to augmentation by bringing the paralyzed vocal cord physically closer to the unaffected cord it may improve the quality of the voice.
  3. Reinnervation or rerouting the affected nerves to the vocal cords has been tried but rarely been successful. It is not commonly practiced as a treatment for vocal cord paralysis.

Once augmentation or surgical repositioning of the paralyzed vocal cord has occurred, speech therapy will still be needed to help fine-tune the voice quality.

In life-threatening cases of vocal cord paralysis, immediate action will need to be taken by the physician to ensure your safety. Often, a tracheotomy will need to be performed (an opening is surgically created in the neck and directly into the trachea to allow breathing—this is also called a stoma). Tracheotomies can be permanent or temporary depending on the severity of vocal cord paralysis.

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By Kristin Hayes, RN
Kristin Hayes, RN, is a registered nurse specializing in ear, nose, and throat disorders for both adults and children.