Vocal Cord Paralysis

Vocal cord paralysis is a voice disorder that occurs when one or both of the vocal cords (or vocal folds) do not open or close properly. Vocal cord paralysis is a common disorder, and symptoms can range from mild to life-threatening.

The vocal cords are two elastic bands of muscle tissue located in the larynx (voice box) directly above the trachea (windpipe). The vocal cords produce voice when air held in the lungs is released and passed through the closed vocal cords, causing them to vibrate. When a person is not speaking, the vocal cords remain apart to allow breathing.



The left vocal cord is affected more often than the right one. Females are affected more often than males.

Other Names
The following are some other names for vocal cord paralysis:


 * unilateral vocal fold paralysis
 * neurogenic hoarseness
 * vocal cord paresis

Symptoms
Below are some symptoms of vocal cord paralysis:


 * abnormal voice changes
 * changes in voice quality
 * discomfort from vocal straining (e.g., if only one vocal cord is damaged, the voice is usually hoarse or breathy)
 * changes in voice quality (e.g., loss of volume or pitch)

Someone who has vocal cord paralysis often has difficulty swallowing and coughing because food or liquids slip into the trachea and lungs. This happens because the paralyzed cord or cords remain open, leaving the airway passage and the lungs unprotected.

Damage to both vocal cords, although rare, usually causes difficulty in breathing because the air passage to the trachea is blocked.

Causes
Vocal cord paralysis can have many causes:


 * head trauma
 * neurologic insult (e.g., stroke)
 * neck injury
 * lung or thyroid cancer
 * tumor pressing on a nerve
 * viral infection

Paralysis can also occur after surgery if the nerves of the vocal cords are damaged. In older people, vocal cord paralysis is a common problem affecting voice production. People with certain neurologic conditions, such as multiple sclerosis or Parkinson disease, or people who have had a stroke may experience vocal cord paralysis. In many cases, however, the cause is unknown.

Diagnosis
Vocal cord paralysis is usually diagnosed by an otolaryngologist–a doctor who specializes in ear, nose, and throat disorders. The doctor notes the symptoms and determines how and when the voice problems started. This aids in determining the cause. Next, the otolaryngologist listens carefully to the patient's voice to identify breathiness or harshness. Then, using an endoscope–a tube with a light at the end–the otolaryngologist looks directly into the throat at the vocal cords (see video below). A speech-language pathologist may also use an acoustic spectrograph, an instrument that measures voice frequency and clarity, to study the patient's voice and document its strengths and weaknesses.



Treatment
There are several methods for treating vocal cord paralysis, among them surgery and voice therapy. In some cases, the voice returns without treatment during the first year after damage. For that reason, doctors often delay corrective surgery for at least a year to be sure the voice does not recover spontaneously. During this time, the suggested treatment is usually voice therapy, which may involve exercises to strengthen the vocal cords or improve breath control during speech. Sometimes, a speech-language pathologist must teach patients to talk in different ways. For instance, the therapist might suggest that the patient speak more slowly or consciously open the mouth wider when speaking.

Surgery involves adding bulk to the paralyzed vocal cord or changing its position. To add bulk, an otolaryngologist injects a substance, commonly Teflon, into the paralyzed cord. Other substances currently used are collagen, a structural protein; silicone, a synthetic material; and body fat. The added bulk reduces the space between the vocal cords so the healthy cord can make closer contact with the paralyzed cord and thus improve the voice.

Sometimes an operation that permanently shifts a paralyzed cord closer to the center of the airway may improve the voice. Again, this operation allows the healthy cord to make better contact with the paralyzed cord. Adding bulk to the vocal cord or shifting its position can improve both voice and swallowing. After these operations, patients may also undergo voice therapy, which often helps to fine-tune the voice.

Treating people who have two paralyzed vocal cords may involve performing a surgical procedure called a tracheotomy to help breathing. In a tracheotomy, an incision is made in the front of the patient's neck and a breathing tube (tracheotomy tube) is inserted through a hole, called a stoma, into the trachea. Rather than breathing through the nose and mouth, the patient now breathes through the tube. Following surgery, the patient may need therapy with a speech-language pathologist to learn how to care for the breathing tube properly and how to reuse the voice.

Living with Vocal Cord Paralysis
Vocal cord paralysis can be frustrating and sometimes debilitating, especially since the voice is so important in everyday life. A speech therapist can help patients develop the skills needed to communicate. Although speech therapy can improve the voice, there is the possibility that it will not be as it once was. Speech therapists can help teach ways to compensate for what was lost.

Research
The National Institute on Deafness and Other Communication Disorders (NIDCD) supports research studies that help provide new clinical measurements to diagnose vocal cord paralysis. For instance, computer software is being developed that can describe important aspects of the health of a person's larynx by analyzing the sounds it produces. By measuring instabilities in the motion of the vocal cords, the software may allow scientists and treatment clinics to relate these measurements to the study of the misuse of the voice and help diagnose disorders such as muscle paralysis and tissue loss.

Currently, the treatment for patients with damage to both vocal cords involves a tracheotomy, which may, however, cause voice production problems and decrease protection of the lungs in an effort to improve the airway. Recent studies show that another feasible approach to laryngeal rehabilitation may be using an electrical stimulation device to activate the reflexes of the paralyzed muscles that open the airway during breathing.

Clinical Trials
In 2007, preliminary results were reported of the largest clinical trial designed to test calcium hydroxylapatite as a bulking agent for vocal cords that are paralyzed. The compound, also called CaHA, was approved for the treatment of vocal cord paralysis by the Food and Drug Administration in the late 1990s. In the trial, 68 patients with paralysis of either one or both vocal cords were given calcium hydroxylapatite. After six months, 56% and 38% of the patients reported significant and moderate improvements in voice, respectively. Other improvements in voice and vocal cord function were also apparent.

National Institutes of Health has a listing of ongoing clinical trials