Vocal cord paralysis occurs when the nerve impulses to the voice box (larynx) are disrupted. This results in paralysis of the vocal cord muscles. In most cases of vocal cord paralysis, only one vocal cord is paralyzed. Vocal cord paralysis can affect the ability to speak and even breathe. Vocal cords not only produce sound, but they also protect the airway by preventing food, drink and even saliva from entering the windpipe (trachea) which could cause choking. When vocal cord paralysis has been diagnosed, a cause should be actively sought. Possible causes include nerve damage during surgery, viral infections and certain cancers.