Prospective Voice Assessment After Thyroidectomy Without Recurrent Laryngeal Nerve Injury

Background: Thyroidectomy, a surgical procedure for thyroid disorders, is associated with postoperative voice changes, even in cases without recurrent laryngeal nerve (RLN) injury. Our study evaluates the prevalence and predictors of voice disorders in thyroidectomy patients without RLN injury. Methods: Our single-center prospective study at the University Hospital Center Zagreb included 243 patients, with pre- and postoperative voice evaluations using acoustic analysis and videostroboscopy. Logistic regression, chi-square, MANOVA, and non-parametric tests assessed the impact of surgical, sociodemographic, and lifestyle factors. Results: The study analyzed 243 participants (141 lobectomy, 102 total thyroidectomy). Postoperative voice disorders occurred in 200 patients (100 lobectomy, 100 total thyroidectomy); 43 (17.7%) experienced no voice disorders. Significant associations were observed for surgery type (χ² = 29.88, p < 0.001), with total thyroidectomy having higher risk, surgery duration (χ² = 16.40, p < 0.001), thyroid volume (χ² = 4.24, p = 0.045), and BMI (χ² = 8.97, p = 0.011). Gender and age showed no significant correlation. Acoustic parameters differed significantly, with lobectomy patients showing better intensity, jitter, and shimmer values across postoperative measurements. Logistic regression identified surgery type (Exp(B) = 16.533, p = 0.001) and thyroid volume (Exp(B) = 2.335, p = 0.023) as predictors of voice disorders, achieving 82.7% classification accuracy. Multivariate analysis confirmed gender and surgery duration as significant contributors. Surgery duration exceeding 90 min and enlarged thyroid volume negatively influenced outcomes. Significant acoustic differences were also linked to BMI categories, with obese participants exhibiting poorer parameters, particularly shimmer and jitter. Conclusions: Surgery type, thyroid volume, BMI, and surgery duration are most likely significant predictors of postoperative voice disorders.