After a total thyroidectomy a patient complains of a hoarse voice. What may have been damaged and why does this lead to hoarseness?
- It is possible that the operation has caused damage to the recurrent laryngeal nerve.
- This supplies all of the muscles of the larynx, except cricothyroid, and damage, therefore, causes paralysis of the ipsilateral vocal cord, resulting in a hoarse voice.
- The recurrent laryngeal nerves runs close to the inferior thyroid artery, therefore, care must be taking when performing thyroid surgery to not damage it.
- If bilateral RLNs are damaged this will cause airway compromise as the cords are paralysed in the midline. This may require emergency tracheostomy. If both nerves are transected the patient will not be able to speak or cough.
- Additional point: Semon's law dictates that if there is a progressive lesion of the recurrent laryngeal nerve, the abductors are paralysed before the adductors. In an incomplete paralysis, the vocal cord will be brought into the midline by the adductors, but in complete paralysis the cord will fall away to the paramedian position.