Vocal cord movements are the result of the coordinated contraction of various muscles that are controlled by the brain through a specific set of nerves. Vocal cord paralysis and paresis result from abnormal nerve input to the voice box muscles.
Paresis is the partial interruption of the nerve impulse, resulting in weak or abnormal motion of the vocal cords.
Paralysis is the total interruption of nerve impulse, resulting in no movement of the vocal cords. A vocal cord paralysis on one side usually leads to significant voice problems and sometimes trouble swallowing liquids. This is because the vocal cords cannot close completely, leaving a gap between them.
When both vocal cords are paralyzed, breathing is a major concern, since the vocal cords cannot open adequately to allow comfortable breathing. A tracheotomy (breathing tube in the neck) may be necessary when both vocal cords are paralyzed.
Vocal Cord Paralysis and Paresis Causes
The most common cause of unilateral vocal cord paralysis is surgery. Since the recurrent laryngeal nerve has a long course through the neck and chest, it is vulnerable to injury from many types of surgeries, particularly thyroid, chest and esophageal, and cervical spine surgeries.
Tumors located anywhere along the course of the recurrent laryngeal nerve may also cause vocal cord paralysis, so your surgeon may order imaging studies to rule out lung cancer or other types of cancers.
Other causes of vocal cord paralysis include viral infections and trauma. Sometimes the cause of the vocal cord paralysis cannot be determined.
Vocal cord paresis is much more common than paralysis, with the most common cause being viral infections.
Vocal Cord Paralysis and Paresis Diagnosis
Laryngeal electromyography (LEMG) can be used to measure the nerve activity to the vocal cords. This allows your surgeon to determine if the vocal cord is paralyzed (nerve injury) or fixated (joint injury). LEMG also gives information about the potential for a nerve injury to recover on its own. LEMG is particularly useful in making this diagnosis, in combination with the laryngeal examination and a speech pathology evaluation.
Vocal Cord Paralysis and Paresis Treatment
The treatments for vocal cord paresis and paralysis are voice therapy and phonosurgery, an operation that repositions or reshapes the vocal cords to improve voice function.