Causes

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.