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. Paralysis of both of your vocal cords is a rare but serious condition. This can cause vocal difficulties and significant problems with breathing and swallowing.

Signs and symptoms of vocal cord paralysis may include:

• A breathy quality to the voice
• Hoarseness
• Noisy breathing
• Loss of vocal pitch
• Choking or coughing while swallowing food, drink or saliva
• The need to take frequent breaths while speaking
• Inability to speak loudly
• Loss of your gag reflex
• Ineffective coughing
• Frequent throat clearing

In vocal cord paralysis, the nerve impulses to your voice box (larynx) are disrupted, resulting in paralysis of the muscle. Doctors often don't know the cause of vocal cord paralysis. 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 or parathyroid glands, 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 in or around the muscles, cartilage or nerves controlling the function of your voice box and can cause vocal cord paralysis.
• Infections. Some infections, such as Lyme disease, Epstein-Barr virus and herpes, can cause inflammation and directly damage the nerves in the larynx.
• Neurological conditions. If you have certain neurological conditions, such as multiple sclerosis or Parkinson's disease, you may experience vocal cord paralysis.

Factors that may increase your risk of developing vocal cord paralysis include:

• Undergoing throat or chest surgery. People who need surgery on their thyroid, throat or upper chest have an increased risk of vocal cord nerve damage. Sometimes breathing tubes used in surgery or to help you breathe if you're having serious respiratory trouble can damage the vocal cord nerves.
• Having a neurological condition. People with certain neurological conditions — such as Parkinson's disease or multiple sclerosis — are more likely to develop vocal cord weakness or paralysis.

Breathing problems associated with vocal cord paralysis may be so mild that you just have a hoarse-sounding voice, or they can be so serious that they're life-threatening.

Because vocal cord paralysis keeps the opening to the airway from completely opening or closing, other complications may include choking on or actually inhaling (aspirating) food or liquid. Aspiration that leads to severe pneumonia is rare but serious and requires immediate medical care.