Vocal cord paralysis: Inability of one or both vocal folds (vocal cords) to move. The paralysis is usually due to damage to the nerves going to the vocal cords or due to damage to the brain itself.
In more technical terms, vocal cord paralysis may result from lesions in the nucleus ambiguus or its supranuclear tracts in the brain, the main trunk of the vagus nerve, or the recurrent laryngeal nerves (which supply the larynx. Intracranial (brain) tumors, strokes, and demyelinating diseases can cause nucleus ambiguus paralysis. Neoplasms at the base of the skull and trauma of the neck cause paralysis of the vagus nerve. Recurrent laryngeal paralysis is caused by neck or thoracic lesions (such as aortic aneurysm; mitral stenosis; tumors of the thyroid gland, esophagus, lung, or mediastinal structures), trauma, thyroidectomy, neurotoxins (such as lead), infections (such as diphtheria), cervical spine injury or surgery, or viral illness.