Assessment of Vocal Fold Function Using Transcutaneous Laryngeal Ultrasonography and Flexible Laryngoscopy

Abstract

Thyroid and parathyroid surgical procedures are common operations. Owing to the close anatomic relationship between the thyroid and parathyroid glands and the laryngeal nerves, iatrogenic injury to the recurrent laryngeal nerve (RLN) with subsequent vocal fold paralysis (VFP) or paresis is one of the most commonly encountered complications. Mechanisms of iatrogenic RLN injury may include mechanical (ie, compression, crush, stretch, or laceration), thermal, or vascular (ie, ischemic injury) factors. Nonetheless, the presence or absence of RLN dysfunction alone does not predict functional voice outcome after thyroidectomy. Other mechanisms can affect vocal fold function, including injury to the external branch of the superior laryngeal nerve; postoperative inflammation; laryngeal edema; surgical trauma to the cricothyroid muscle, the extralaryngeal or strap muscles, or the cricoarytenoid joint; endotracheal intubation-related trauma; and laryngotracheal fixation.^1-3 Vocal manifestations from these various injuries can range from a seemingly normal voice or transient voice fatigue to profound and permanent dysphonia with a substantially adverse effect on the patient’s quality of life.^4-6 Such complications are of concern not only for the patients but for the surgeons because these complications are common causes of medicolegal litigation.⁷