Impact of thyroidectomy without laryngeal nerve injury on vocal quality characteristics: an objective multiparameter approach

Abstract

Objectives/hypothesis: The main purpose of this study was to determine the impact of thyroidectomy on the subjective and objective vocal quality using the Dysphonia Severity Index. It was hypothesized that objective measures of vocal function and other vocal characteristics would change (temporarily or permanently) from the presurgical to the postsurgical conditions, even with the entire preservation of the laryngeal nerve, due to the surgical approach and other influencing factors.

Study design: Prospective study in which 44 subjects were studied before (1 week) and three times post-thyroidectomy.

Methods: Subjective (auditory perceptual evaluation and videolaryngostroboscopy) and objective (aerodynamic, vocal range, acoustic, and Dysphonia Severity Index measurements) assessment techniques were used.

Results: Paired samples t test indicated a significant decrease of the highest frequency, the highest intensity, the fundamental frequency, and the Dysphonia Severity Index in the first postoperative condition. When a repeated measures analysis of variance was performed with the pre- and all the postoperative moments of evaluation taken into account, no significant difference was noted for any of the objective voice characteristics.

Conclusions: After thyroidectomy subjects had a normal perceptual and objective vocal quality corresponding with a Dysphonia Severity Index of 66%, and there is no permanent change of the vocal performance. Moreover, there is no psychosocial handicapping effect of the vocal quality, but immediately post-thyroidectomy there are more vocal complaints. To what extent thyroidectomy causes (temporary or permanent) alterations of the singing voice in elite vocal performers is subject to further research.