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

IMPORTANCE Evaluation of preoperative and postoperative vocal fold function is important in patients undergoing thyroid or parathyroid surgical procedures. Transcutaneous laryngeal ultrasonography (TLUSG) has been proposed as a promising noninvasive technique and alternative to flexible fiberoptic laryngoscopy. OBJECTIVE To determine whether TLUSG can be an alternative to flexible laryngoscopy in evaluating vocal fold function. DESIGN, SETTING, AND PARTICIPANTS A prospective study was performed from March 1, 2013, to July 31, 2014. Patients who were scheduled to undergo thyroid or parathyroid surgery by a single surgeon at a North American, university-based tertiary care center and who agreed to undergo preoperative and postoperative TLUSG and flexible fiberoptic laryngoscopy were enrolled. Patients were divided into 2 groups: nonoverweight (body mass index [calculated as weight in kilograms divided by height in meters squared] < 25) and overweight or obese (body mass index >= 25). Follow-up was completed on February 28, 2015, and data were analyzed from March 1, 2013, to February 28, 2015. INTERVENTIONS Preoperative and postoperative TLUSG and flexible fiber optic laryngoscopic assessments of vocal fold function. MAIN OUTCOMES AND MEASURES The findings of TLUSG and flexible fiber optic laryngoscopy were compared for all patients and each body mass index group to assess the accuracy of TLUSG in assessing vocal fold function. RESULTS A total of 250 patients (500 vocal folds) underwent evaluation, of whom 208 (83.2%) were women and with a mean (SD) age of 52.7 (14.3) years. On flexible fiberoptic laryngoscopy findings, 13 patients had preoperative vocal fold paralysis (VFP), and 14 postoperative new incidents of VFP were identified. Only 7 (53.9%) of the preoperative cases of VFP and 15 (55.6%) of the postoperative cases of VFP were identified by TLUSG. The sensitivity, specificity, and accuracy of preoperative TLUSG were 53.8%, 50.5%, and 50.6%, respectively; for postoperative TLUSG, 55.6%, 38.7%, and 39.6%, respectively. In the nonoverweight group, the preoperative TLUSG sensitivity, specificity, and accuracy were 100%, 70.0%, and 70.5%, respectively; in the overweight-obese group, 45.4%, 43.4%, and 43.5%, respectively (odds ratio, 3.16; 95% Cl, 2.06-4.84; P < .001). Postoperative visualization of the vocal folds was more challenging, with a sensitivity, specificity, and accuracy of 83.3%, 55.6%, and 56.8%, respectively, in the nonoverweight group, and 47.6%, 32.6%, and 33.4%, respectively, in the overweight-obese group (odds ratio, 2.62; 95% Cl, 1.75-3.94; P < .001). CONCLUSIONS AND RELEVANCE When evaluation of vocal fold function is indicated in patients undergoing thyroid and parathyroid surgery, TLUSG should not be considered as an alternative to the current practice of flexible fiberoptic laryngoscopy. Adequate ultrasonographic visualization of the vocal folds and arytenoids is challenging, especially in overweight and obese patients and in the postoperative setting.