Assessing the Validity of Transcutaneous Laryngeal Ultrasonography (TLUSG) After Thyroidectomy: What Factors Matter?

Although transcutaneous laryngeal ultrasound (TLUSG) is an excellent, noninvasive way to assess vocal cord (VC) function after thyroidectomy, some patients simply have "un-assessable" or "inaccurate" examination. Our study evaluated what patient and surgical factors affected assessability and/or accuracy of postoperative TLUSG. Five hundred eighty-one consecutive patients were analyzed. All TLUSGs were done by one operator using standardized technique, whereas direct laryngoscopies (DL) were done by an independent endoscopist to confirm TLUSG findings. Their findings were correlated. TLUSG was "unassessable" if a parts per thousand yen1 VC could not be clearly visualized, whereas it was "inaccurate" if the TLUSG and DL findings were discordant. Demographics, body habitus, neck anthropometry, and position of incision were correlated with assessability and accuracy of TLUSG. Twenty-nine (5.0 %) patients had "unassessable" VCs; among the "assessable" patients, 29 (5.3 %) patients had "inaccurate" TLUSG. More than one-third (38.5 %) of VC palsies (VCPs) were "inaccurate." Older age (odds ratio [OR] = 1.055, 95 % confidence interval [CI] 1.016-1.095, p = 0.005), male sex (OR = 13.657, 95 % CI 2.771-67.315, p = 0.001), taller height (OR = 1.098, 95 % CI 1.008-1.195, p = 0.032), and shorter distance from cricoid cartilage to incision (OR = 0.655, 95 % CI 0.461-0.932, p = 0.019) were independent factors for "unassessable" VCs, whereas older age (OR = 1.028, 95 % CI 1.001-1.056, p = 0.040) was the only factor of incorrect assessment. Older age, male sex, tall in height, and incision closer to the thyroid cartilage were independent contributing factors for unassessable VCs, whereas older age was the only contributing factor for inaccurate postoperative TLUSG. Because more than one-third of VCPs were actually normal, patients labeled as such on TLUSG would benefit from laryngoscopic validation.