Beyond the Neck: When Is Thoracic Operation Needed for Thyroidectomy?

Abstract

Although most patients with intrathoracic thyroid glands can undergo thyroidectomy via a cervical incision, some cases necessitate intraoperative thoracic surgery assistance. This study aimed to identify CT findings that predict the need for thoracic surgery assistance during thyroidectomy. We reviewed administrative data at our institution (2012 to 2023), encompassing 7,370 thyroidectomies, to identify patients who underwent thyroidectomy for intrathoracic thyroid glands, defined as thyroid glands that extended below the sternal notch. Detailed CT analysis was conducted, including measurements of intrathoracic thyroid dimensions, shape, extension to posterior mediastinum, and relation to thoracic inlet. Receiver operating characteristic curve analysis and multivariable regression analysis were performed to identify the most accurate independent predictors of the need for intraoperative thoracic surgery assistance. Among 255 patients with intrathoracic thyroid glands, 34 (13.3%) required intraoperative thoracic surgery assistance. Patients needing thoracic assistance had significantly larger intrathoracic thyroid glands in anteroposterior, craniocaudal, and horizontal dimensions compared with those without. Additionally, their thyroid glands were more likely to enlarge below the sternal notch or extend into the posterior mediastinum receiver operating characteristic curve indicated that distance from inferior border of thyroid gland to sternal notch (area under curve [AUC] = 0.94) is a better predictor than distance to aortic arch (AUC = 0.91) or sternal angle (AUC = 0.91). Thresholds of distance to sternal notch 5.3 cm or more, anteroposterior dimension 5.2 cm or more, and horizontal dimension 5.3 cm or more provided 80% sensitivity and 70% or more specificity for predicting the need for thoracic assistance. Multivariable regression analysis identified thyroid increasing in size below sternal notch, distance to sternal notch 5.3 cm or more, and horizontal dimension 5.3 cm or more as independent predictors for intraoperative thoracic assistance. Thyroid glands extending 5.3 cm or more below sternal notch, enlarging below sternal notch, or having a horizontal dimension 5.3 cm or more warrant preoperative thoracic surgery consultation for potential intraoperative assistance.