Vocal cord paralysis can affect your ability to read books to your children, cheer for your hometown team or sing your favorite songs.

But your vocal cords do more than just produce sound. They also protect your airway by preventing food and drink — and even your saliva — from entering your windpipe (trachea) and causing you to choke. Rarely, vocal cord paralysis can be life-threatening. If both cords are paralyzed in the closed position, you won't be able to breathe properly.

Vocal cord paralysis can occur after neck or throat surgery, when the nerves that control the vocal cords are intentionally or accidentally damaged. Thyroid cancers or lung tumors also may cause vocal cord paralysis.

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Vocal cords and speech

Your vocal cords are two flexible bands of muscle tissue that sit at the entrance to the windpipe (trachea). When you speak, the bands come together and vibrate to make sound. The rest of the time, the vocal cords are relaxed in an open position, so you can breathe.

In most cases of vocal cord paralysis, only one vocal cord is paralyzed. If the vocal cord is paralyzed in a closed position, it reduces airflow into the lungs. If it's paralyzed in the open position, your voice may be breathy, hoarse or weak.

Depending on the paralyzed position of the vocal cord, signs and symptoms may include:

• A breathy quality to the voice
• Hoarseness
• Choking or coughing while swallowing food, drink or saliva
• The need to take frequent breaths while speaking
• Inability to speak loudly
• Inability to "bear down" while lifting
• Ineffective coughing

If both of your vocal cords are affected, you may experience the signs and symptoms above, as well as significant problems with breathing.

In vocal cord paralysis, the nerve impulses to your voice box (larynx) are interrupted, resulting in paralysis of the muscle. Doctors cannot determine the cause of vocal cord paralysis in as many as half the cases. Known causes may include:

• Injury to the vocal cord during surgery. Surgery on or near your neck or upper chest can result in damage to the nerves that serve your voice box. Surgeries that carry a risk of damage include surgeries to the thyroid, esophagus, neck and chest.
• Neck or chest injury. Trauma to your neck or chest may injure the nerves that serve your vocal cords or the voice box itself.
• Stroke. A stroke interrupts blood flow in your brain and may damage the part of your brain that sends messages to the voice box.
• Tumors. Tumors, both cancerous and noncancerous, can grow around the muscles, cartilages or nerves of your voice box and can cause vocal cord paralysis.
• Inflammation. Arthritis or surgery can cause inflammation and scarring of the vocal cord joints or the space between the two vocal cord cartilages, and this inflammation may prevent your vocal cords from opening and closing. The symptoms and signs mimic vocal cord paralysis even though the vocal cord nerves remain normal. In addition, some viral infections can cause inflammation and damage directly to the nerves in the larynx.
• Neurological conditions. If you have certain neurological conditions, such as multiple sclerosis, you may experience vocal cord paralysis; however, these conditions are more likely to cause vocal cord weakness than complete paralysis.

If you have hoarseness that lasts more than three weeks, or if you notice any unexplained voice changes or discomfort, contact your doctor.

If you've gone to your regular doctor with a concern about your voice, he or she may refer you to an expert in the field. Vocal cord paralysis is usually diagnosed by an ear, nose and throat specialist (otolaryngologist). Your doctor will ask about your symptoms and lifestyle, listen to your voice, and ask you how long you've had voice problems. The following tests may be performed:

• Endoscopy. Your doctor will look at your vocal cords using a mirror and/or a thin, flexible tube (endoscope) with a light at one end and a viewing piece or camera at the other. The endoscope allows your doctor to view your vocal cords directly or on a video monitor to determine whether one or both vocal cords are affected, as well as the movement and position of the vocal cords.
• Laryngeal electromyography. This test measures the electric currents in your voice box muscles. By looking at the pattern of the currents, your doctor can determine the degree of the problem and what types of treatment may be most effective. To obtain these measurements, your doctor inserts small needles into your vocal cord muscles.
• Blood tests and scans. Because a number of diseases may cause a nerve to be injured, you may need additional tests to identify the cause of the paralysis. Tests may include blood work, X-rays, MRI or CT scans.

Breathing problems associated with vocal cord paralysis can range from mild to life-threatening. Because vocal cord paralysis keeps the opening to the airway from completely opening or closing, complications may include choking on or actually inhaling (aspirating) food or liquid. Aspiration can lead to severe pneumonia.

Treatment of vocal cord paralysis depends on the cause, the severity of symptoms and the time from the onset of symptoms. Treatment may include voice therapy, surgery or both. In some instances, your nerve paralysis may return to normal without surgical treatment. For this reason, your doctor may delay surgery for up to a year and suggest voice therapy to keep you from using the voice improperly while the nerves heal.

Voice therapy
Voice therapy sessions involve exercises or other activities to strengthen your vocal cords, improve breath control during speech, prevent abnormal tensions in other muscles around the paralyzed vocal cord and protect your airway during swallowing.

Surgery
Surgical treatments for vocal cord paralysis can improve your ability to speak and to swallow. Surgical options include:

• Bulk injection. To add bulk to the paralyzed vocal cord, a doctor who specializes in ear, nose and throat disorders (otolaryngologist) injects your vocal cord with a substance such as body fat, collagen or another approved substance. This added bulk brings the affected vocal cord closer to the middle of your voice box so that the functioning, moving vocal cord can make closer contact with the paralyzed cord when you speak or swallow.
• Vocal cord repositioning. In this procedure, a surgeon moves a "window" of tissue from the outside of your voice box inward, pushing the paralyzed vocal cord toward the middle of your voice box so that it can better vibrate against your unimpaired vocal cord.
• Tracheotomy. If both of your vocal cords are paralyzed in a closed position, you may have trouble breathing and require a surgical procedure called a tracheotomy. In a tracheotomy, an incision is made in the front of your neck and an opening created directly into the wind pipe (trachea). A breathing tube is inserted, allowing air to bypass the immobilized vocal cords above.

Emerging treatments
Linking the vocal cords to an alternative source of electrical stimulation — perhaps a nerve from another part of the body, or a device similar to a cardiac pacemaker — may restore opening and closing of the vocal cords. Researchers continue to study this and other options.

Vocal cord paralysis can be frustrating and sometimes debilitating, especially since your voice is so important to your personality. A speech therapist can help you develop the skills you need to communicate. Even if you're not able to regain the voice you once had, speech therapy can help you learn effective ways to compensate.