Transcutaneous laryngeal ultrasonography: a reliable, non-invasive and inexpensive preoperative method in the evaluation of vocal cords motility—a prospective multicentric analysis on a large series and a literature review

Thyroidectomy is a largely performed intervention and its rate has sharply increased. The most feared postoperative complication is the recurrent laryngeal nerve paralysis, which is the most frequent cause of medicolegal litigations. Therefore, surgeons have introduced the preoperative evaluation of vocal cords function through laryngoscopy. Transcutaneous laryngeal ultrasonography has been proposed as a non-invasive indirect examination of vocal cords function. The aim of this study is to assess transcutaneous laryngeal ultrasonography reliability as an alternative painless and inexpensive method in the evaluation vocal folds function in patients amenable of thyroid surgery. We conducted a prospective multicentric study on patients affected by thyroid disease referred to the thyroid surgery divisions of two tertiary hospitals. All patients preoperatively underwent transcutaneous laryngeal ultrasonography and subsequently were evaluated via laryngoscopy by a blinded otolaryngologist. The ultrasonographical and laryngoscopical findings were then compared by an external blinded investigator. Our analysis on 396 patients showed an assessability rate of 96.46%, a sensitivity of 96.8%, a specificity of 95.6%, a positive predictive value of 65.2% and a negative predictive value of 99.7% in the identification of vocal cords alterations. A concordance between transcutaneous laryngeal ultrasonography and laryngoscopy of 95.7% was reported. In 14 patients (3.54%), the investigator reported a hard visualization of vocal cords through ultrasonography. Transcutaneous laryngeal ultrasonography is a valid non-invasive and painless alternative method in the assessment of vocal cords in a selected population; moreover, it could be useful in identifying patients addressable to second-level examination.