Anterolateral approach for thyroid swellings: impact on postoperative voice outcomes

Background: The sternothyroid muscle (ST) is routinely divided during grossly enlarged thyroid surgery to facilitate gland exposure. However, the ST is considered to play a role in controlling of pitch in the human voice. In this prospective cohort study, we described an anterolateral approach (AA) by which it was easy to expose the enlarged gland while preserving the ST, and evaluated the impact of this approach on vocal outcomes after total thyroidectomy. Methods: The AA was performed on eligible patients from October 2018 to January 2020 in our department. Consecutive cases hospitalized from March 2020 and followed up to June 2021 who received total thyroidectomy via the midline approach (MA) served as controls. All participants underwent voice analysis before the operation and at 2 weeks and 3 months after the surgery. In 26 patients from AA group, strap muscles were mobilized along the anterior margin of both sternocleidomastoid muscles (SCMs) until 3 cm above the sternal notch followed by thyroidectomy, and their voice outcomes were compared to those of 36 patients from the MA group with a bilateral division of ST. Results: Distribution of age, gender, specimen size, thyroid histopathology and laryngeal nerve identification rates did not differ significantly between groups. At 2 weeks post-surgery, objective assessment of voice change rate indicated no significant difference between groups, whereas the difference appeared to be partially manifest 3 months later. In the single-arm study, the AA group showed a decrease of maximum and fundamental pitch frequency 2 weeks after surgery but showed no difference in fundamental frequency after 3 months. The MA group continued to show a mild decrease in maximum and fundamental frequency at 3 months after surgery. Conclusions: The AA affords sufficient visualization of the superior thyroid vessels and external branch of the superior laryngeal nerve (EBSLN) without sacrificing the integrity of the strap muscles. This approach is a feasible solution for selective difficult thyroid surgery and could reduce the postoperative changes in pitch of voice.