ABSTRACT
PURPOSE: Vocal symptoms have been reported after thyroidectomy and even in the absence of injury to the recurrent laryngeal nerve or the external branch of the superior laryngeal nerve. The aim of this prospective study was to evaluate the subjective and objective voice changes in patients without laryngeal nerve injury after thyroidectomy. METHODS: The subjects had undergone total thyroidectomy for differentiated thyroid carcinoma from November 2007 to December 2008. Twenty-eight subjects (males: 8, females: 20) were selected for this study. Voice analysis was prospectively evaluated in the subjects at the time of preoperation and postoperation (10.8 months for the males and 11.7 months for the females). A subjective analysis was done using the visual analogue scale (VAS, 0: no symptom, 10: severe symptoms) and objective analyses were determined by several parameters such as the fundamental frequency (Fo), jitter, shimmer and the noise to harmonic ratio (NHR) using the multi-dimensional voice program. Maximum phonation time (MPT)was performed as an aerodynamic test. RESULTS: 3 patients (37.5%) among the males and 14 patients (70%) among the females had subjective postoperative voice change. The VAS showed a significant difference for the females (0 to 1.25±0.97, P0.05). The vocal parameters (Fo, jitter, shimmer, NHR) and MPT showed no significant changes for both the males and females (P>0.05). CONCLUSION: Subjective voice changes may occur after thyroidectomy without laryngeal nerve injury. Surgeons should take possible voice changes into consideration when informing patients before thyroidectomy.