Multivariate Analysis of Risk Factors in the Development of a Lower-Pitched Voice After Thyroidectomy

Objectives: Thyroid surgeons frequently encounter outpatients with mobile vocal cords complaining of lower-pitched voices following thyroidectomy. This study investigated the clinical and pathological parameters affecting voice pitch following thyroid surgery. Methods: We analyzed the data of 393 patients with mobile vocal cords and who also underwent thyroid surgery. Speaking fundamental frequency (SFF) and fundamental frequency (F0) were compared before and after surgery. Results: Approximately 26.7% of patients had significantly lowered SFFs (ΔSFF ≥ 12 Hz), and 30.2% exhibited significantly lower sustained vowel F0s (ΔF0 ≥ 12 Hz) following thyroid surgery. On multivariate analysis, only gender: female remained a significant predictor of a clinically significant change in SFF following thyroid surgery (P < .001). Gender: female and extent of surgery: total remained significant predictors of a clinically significant change in F0 after surgery (P = .006 and P = .007, respectively). Conclusions: Appreciable proportions of patients experience lower-pitched voice and related vocal symptoms early after thyroid surgery. Such problems develop more frequently in females who underwent total thyroidectomy.