Vocal cord paralysis may affect one or both vocal cords. Females are affected more often than males.
Paralysis of one vocal cord can result from brain disorders, such as brain tumors, strokes, and demyelinating diseases (such as multiple sclerosis), or damage to the nerves that lead to the voice box (larynx). Nerve damage may be caused by noncancerous (benign) and cancerous (malignant) tumors; neck injury; many types of surgery that involve the neck or chest, such as surgical removal of the thyroid gland, spinal surgery, or heart surgery; a viral infection of the nerves; Lyme disease; neurotoxins (substances that poison or destroy nerve tissue), such as lead, mercury, and arsenic; or the toxins produced in diphtheria. The cause is unknown for some people.
Paralysis of both vocal cords is a life-threatening disorder because the vocal cords cannot open enough to let air through properly. This paralysis can be caused by surgery of the spine through the front of the neck, surgical removal of the thyroid gland, insertion of a breathing tube into the windpipe (tracheal intubation), or diseases that affect the nerves and muscles (such as myasthenia gravis).
Vocal cord paralysis prevents the vocal cords from opening and closing and may affect speaking, breathing, and swallowing. Paralysis may allow food and fluids to be inhaled (aspirated) into the windpipe (trachea) and lungs.
If only one vocal cord is paralyzed, the voice is hoarse and breathy. Usually, the airway is not blocked because the normal cord on the other side opens sufficiently.
When both vocal cords are paralyzed, the voice is reduced in strength but otherwise sounds normal. However, the space between the paralyzed cords is very small, and the airway is inadequate so that even moderate exercise causes difficulty in breathing and a harsh, high-pitched sound (stridor) with each breath.
Doctors try to find the cause of the vocal cord paralysis. They ask questions about all possible causes, including chronic exposure to heavy metals (arsenic, lead, and mercury), use of the drugs phenytoin and vincristine, history of a connective tissue disorder (such as Marfan syndrome), Lyme disease, sarcoidosis, diabetes, and alcoholism.
In addition to asking questions about a person's medical history, doctors base the diagnosis on laryngoscopy. Laryngoscopy is examination of the larynx, with a thin, flexible viewing tube.
Additional testing may include
If only one side is paralyzed, an operation can be done to move the paralyzed vocal cord to the best position for more normal speech. The operation may involve inserting an adjustable spacer near the paralyzed cord or injecting a substance into the paralyzed cord to move the cords closer together, improve the voice, and prevent aspiration.
When both sides are paralyzed, keeping the airway open adequately is difficult. A tracheotomy (surgery to create an opening into the trachea by cutting through the front of the neck) may be needed. The tracheotomy opening may be permanent or may be used only when the person has an upper respiratory tract infection.
In another procedure, called an arytenoidectomy, the vocal cords are permanently separated, thus widening the airway. However, this procedure may worsen voice quality.
Laser removal of part of one or both vocal cords is preferred to arytenoidectomy and helps widen the airway. If done correctly, laser removal can preserve satisfactory voice quality and eliminate the need for a tracheotomy.