Vocal cord paralysis is exactly as it sounds – or rather, it would be if affected patients could speak properly. The vocal cords, also known as vocal folds, are a matched pair of muscles located in the throat within a section appropriately named ‘the voice box’ (or larynx). In order to produce sound, such as when singing or speaking, these bands of muscle tissue must meet and vibrate against each other as air passes through from the lungs. But just like it takes two to make a marriage work, if one vocal fold doesn’t meet the other halfway, we have a problem.
Vocal cord paralysis occurs when one or both vocal folds lose the ability to move effectively due to damage to the nerve and its branches that supply these muscles. The result is a voice that sounds fatigued, breathy, and hoarse – in other words, a voice that means you need to rethink auditioning for Hamilton. Other symptoms of vocal cord paralysis include:
- Noisy breathing
- Difficulties with vocal pitch and volume
- Ineffective coughing
- Breathlessness when speaking
Because normally functioning vocal folds automatically close during swallowing to seal the airways, vocal cord paralysis may also present with choking as solids or liquids (including even saliva) are accidentally directed down the windpipe (trachea) instead of food pipe (esophagus). This situation, known as aspiration, in severe cases can result in death. On the other hand, some studies have found up to 40% of unilateral vocal cord paralysis (involving only the one side) can be present without any symptoms and may be only found coincidentally during the course of other medical investigations.
What Causes Vocal Cord Paralysis?
The vocal cords are supplied by the vagus nerve and its direct branches known as the recurrent laryngeal nerves. Damage along any part of this pathway reduces the innervation received by the vocal folds and weakens their action.
Unilateral vocal cord paralysis is the most common situation. More often it is the left-sided vocal cord affected as the left recurrent laryngeal nerve must run a longer course from the brainstem, meaning there is more chance for it to be damaged at some point. Around a third of unilateral vocal cord paralysis cases are a result of tumors, such as those located at the base of the skull or thyroid gland; another third are due to trauma, including from neck or chest surgery, intubation during respiratory distress, and aneurysms or other vascular disease; the final approximate third of cases have no identifiable cause, with a large proportion of this presumed to be from viral infection.
When both sides of the vocal folds are affected this is termed bilateral vocal cord paralysis. Approximately 50% of bilateral cases are caused by injury to the vagus nerve as a result of surgery, particularly thyroid surgery.
Vocal cord paralysis may also be a sign of other serious systemic disease affecting the innervation of the vocal folds, including multiple sclerosis, Parkinson’s disease, or stroke.
How is Vocal Cord Paralysis Diagnosed and Treated?
Vocal cord paralysis is best diagnosed by an ENT specialist. In addition to taking a detailed history of symptoms and any risk factors, direct visualization of the vocal cords using laryngoscopy can reveal the positioning of the folds and aid in determining if one or both are affected.
To guide appropriate treatment, other investigations are typically undertaken to identify the underlying cause. These include blood tests that may indicate the presence of systemic disease, heavy metal poisoning, or infection, as well as medical imaging, such as CT or MRI scans of the head, neck and chest. Electromyography is a procedure to measure the electrical impulses reaching the vocal folds and can provide some useful prognostic information about whether the cords may recover some or all of their function.
The aim of treatment is slightly different between unilateral and bilateral vocal cord paralysis. In unilateral cases the main issue is difficulties with speech but as the functional fold can still move, breathing is not typically a problem. In these situations, surgical treatment aims to bring the cords closer together to be able to produce sound through proper vibration. In bilateral paralysis the most significant concern is the airway, as paralyzed cords sit in a half-closed position, restricting airflow through the trachea. Treatment options here aim to re-establish and protect the airway.
Vocal therapy under appropriate supervision can help to rehabilitate the vocal folds, improving breathing during speech, protecting the windpipe during swallowing, and avoiding abnormal overuse of the surrounding muscles. Therapy typically involves specialized exercises to strengthen the vocal cords.
Vocal Cord Augmentation
Vocal cord augmentation is a category of surgical treatments that aim to bring the paralyzed cord closer to the functioning one to allow vibration for normal speech and to prevent aspiration (and choking and death).
Medialization laryngoplasty may use either a structural implant or an injectable substance to reposition the weak vocal cord and bring it closer to the middle of the larynx. Traditionally, unilateral paralysis has been treated with voice therapy alone for the first 12 months or so while the doctor waits to see if the paralysis improves spontaneously without surgical intervention. However, some doctors are now advocating for early intervention with medialization injections as this treatment is simple, safe, and provides immediate results as evidenced in the video here: https://www.bergerhenryent.com/vocal-cord-paralysis/. Being able to perform the treatment in the clinic under local anesthetic reduces the costs and risks of general anesthesia and also provides the advantage of immediately seeing (or rather, hearing) the outcome of the procedure.
Tracheotomy protects the airways during bilateral vocal cord paralysis by inserting a breathing tube to bypass the voice box altogether. This may be a permanent or temporary measure depending on the situation.
Research into the use of electrical stimulation to the vocal cords has been going on for many years. At this point we still require more results about its effectiveness as studies have not found a significant improvement to vocal fold movement using electrical stimulation over conventional voice therapy. Once an effective electrical stimulation device can be developed it may help to reduce the number of bilateral vocal cord paralysis cases requiring tracheotomy.
It takes two to tango and also two to sing and not aspirate. Your Les Miserables dreams don’t have to be over just yet but as vocal cord paralysis has potentially serious implications, if you notice any of the persisting symptoms listed above it is best to seek care from an experienced ENT doctor and postpone that audition for now.