The Clinical Significance of Detecting Blood Supply to the Inferior Parathyroid Gland Based on the “Layer of Thymus-Blood Vessel-Inferior Parathyroid Gland” Concept

Abstract

Objective. How to preserve the inferior parathyroid gland (IPTG) in situ during central neck dissection (CND) is the major concern of thyroid surgeons. The “layer of thymus-blood vessel-IPTG” (TBP layer) concept showed to be effective in preserving IPTG. The objective of this study was to identify the origin and course of blood supply to IPTG (IPBS) within the TBP layer and to take key points of operation during CND. Design. This is a retrospective control study. Participants. Patients who underwent thyroidectomy plus CND using the TBP layer concept and conventional technique between 2017 and 2019 were enrolled. Measurements. The origin and course of IPBS in relation to recurrent laryngeal nerve (RLN) and thymus and prevalence of hypoparathyroidism were detected. Results. A total of 71.3% of IPTGs (251 of 352) were supplied by ITA branches, defined as type A. Type A was further divided into Types A1 (branches of ITA, coursing laterally to the RLN (53.1%, 187 of 352)) and A2 (branches of ITA, traversing medially to the RLN (18.2%, 64 of 352)). Type A2 was more common on the right side than on the left side ( $P<0.001$ ). Fifty-five (15.6%) IPTG feeding vessels originated from the thymus or mediastinum. Nineteen (5.4%) IPTGs were supplied by branches of the superior thyroid artery. The incidence of transient hypoparathyroidism decreased from 45.7% to 3.6% ( $P<0.001$ ), in the TBP layer group compared with the conventional technique group. Conclusion. The origin and course of IPBS follow a definite pattern. This mapping and precautions help surgeons optimize intraoperative manipulations for better preservation of IPBS during CND.