Phonatory function in patients with well-differentiated thyroid carcinoma following meticulous resection of tumors adhering to the recurrent laryngeal nerve.

Abstract

Well-differentiated thyroid carcinomas (WDTCs) sometimes adhere firmly to the recurrent laryngeal nerve (RLN), while allowing normal mobility of the vocal fold (VF). Meticulous dissection of the adhered tumor from the RLN is known to be effective, preserving VF mobility and oncological safety. However, phonatory function following this preservation procedure has yet to be evaluated sufficiently. The objective of this study was to examine phonatory function following the preservation procedure. Ten patients with WDTCs, demonstrating normal preoperative VF mobility with tumors adhering to the RLN, underwent the preservation procedure between 2000 and 2013 (preservation group). During the same period, nine patients with WDTCs demonstrating normal VF mobility underwent resection and reconstruction of the tumor-invaded RLNs (reconstruction group). Phonatory function, including maximum phonation time (MPT), mean flow rate (MFR), jitter, shimmer, harmonics-to-noise ratio, and GRBAS scale score, was evaluated and compared statistically between the two groups. The mean values of MPT and MFR in the preservation group were at normal levels. Both G and B scores of GRBAS scale were at near-normal levels. Additionally, the mean B score of the GRBAS scale was significantly better in the preservation group than in the reconstruction group. When normal VF mobility is observed preoperatively, meticulous resection for preserving RLN would contribute to maintain not only normal level of MPT and MFR, but also to provide better B score of GRBAS scale than RLN resection followed by immediate reconstruction.