The vocal cords are two bands of tissue located in the larynx (voice box) above the trachea (windpipe). The vocal cords open and close like a valve during breathing, swallowing and voicing. Voice is produced when exhaled lung air passes over the closed vocal cords and causes them to vibrate. During swallowing, the vocal cords close to protect the airway.
Vocal cord paralysis is a condition that occurs when one or both of the vocal cords (or vocal folds) do not move properly. The lack of movement may be partial (paresis) or complete (paralysis), and the symptoms can range from mild to life threatening. A person who has a vocal cord paralysis may experience voice and/or swallowing difficulties.
Vocal cord paralysis is caused by damage to the nerves or muscles of the vocal cord. If the nerve is damaged, the brain is not able to send a message through the nerve to the muscle to tell the muscle to move. If the muscle is damaged, it may not be able to respond to the message it receives from the nerve.
Vocal cord paralysis may be caused by injury to the head including a neurologic injury such as a stroke, a neck injury or surgery, lung or thyroid cancer, a tumor pressing on the nerve, or even a viral infection. Other neurologic conditions, such as Parkinson's, Amyotrophic lateral sclerosis (ALS) or multiple sclerosis may experience some degree of vocal cord paralysis. In many cases, the cause is unknown.
Symptoms will vary from person to person depending of the degree of weakness and the position of the paralyzed cord. Some degree of change in the voice quality including weakness, breathy voice, vocal fatigue and discomfort from vocal straining, and/or decreased ability to control pitch or loudness are possible. Swallowing difficulty, particularly coughing when drinking or eating may also occur. Damage to both vocal cords, although rare, causes greater difficulty in breathing because the air passage to the trachea is blocked.
Diagnosis starts with an examination by an otolaryngologist, often along with a speech pathologist. As with other disorders of the voice, a complete voice history and physical examination of your head and neck is undertaken. Next, using a small flexible tube called an endoscope, the otolaryngologist looks directly into the throat at the vocal cords. Additional acoustic and durational measures of the voice may be taken to document the voice and its strengths and weaknesses. The otolaryngologist may order additional tests to determine why the vocal cord movement is impaired. A CT scan of the neck and chest is often done to study the nerve to the vocal cord. In some cases, an electromyography (EMG) study may be used to measure the electrical signal from the nerve to the vocal cord. This study is done in the clinic and involves placement of very small electrodes into the muscles of the vocal cords to measure the electrical signal.
The symptoms of vocal cord paralysis will vary for individuals, and the treatment options are usually guided by symptoms. In some cases, the voice may return without any treatment within the first year after damage. During that time, the suggested treatment is usually voice therapy. Voice therapy will not restore movement to the vocal cord, but will involve training to help utilize the structures for voice production with maximal efficiency, and can help prevent bad compensatory habits from forming.
During the time of monitoring for recovery, regular re-evaluations will be performed to assess progress and potential for full recovery.
If recovery does not occur, there are other treatment options. Temporary injections into the vocal cords to add bulk and allow for better closure of the cords can help both swallowing and voice. If damage is felt to be permanent, a more permanent surgical procedure to place an implant into the paralyzed vocal cord to help shift its position to midline may be done.
Treatment in cases where both vocal cords are paralyzed may involve a surgical procedure called a tracheotomy to help breathing.