The Zuckerkandl's tubercle: a useful anatomical landmark for detecting both the recurrent laryngeal nerve and the superior parathyroid during thyroid surgery.

Zuckerkandl's tubercle (ZT) is a well-documented anatomical structure. This study evaluated ZT anatomical characteristics in terms of the recurrent laryngeal nerve (RLN) and the superior parathyroid (SP). The study involved 325 (10 with benign tumors and 315 with malignancies) patients who underwent thyroidectomy between February and June 2007. ZTs were classified according to size: Grade 0 (unrecognizable), Grade I (</=5 mm), Grade II (6~10 mm) and Grade III (>10 mm). The incidence and size of the ZT and its positional relationship to the RLN and SP were investigated during thyroid surgery. ZTs were identified in most patients (right 89.3%, left 85.6%). The distribution of ZTs according to grade was as follows: Grade 0, right 10.7% and left 14.4%; Grade I, right 7.9% and left 11.1%; Grade II, right 43.5% and left 38.5%; and Grade III, right 37.9% and left 35.9%. The most common RLN course was in a groove between the ZT and the main body of the thyroid. The majority of SPs were cranial to the ZT which was located at the 1 or 2 o'clock position (96.1%) in the left, and at 10 or 11 o'clock (95.2%) in the right. The smaller the size of the ZT, the greater the distance between the ZT and the SP. There was a constant relationship between the ZT and RLN and SP. Therefore, an identification of ZT and an understanding of the relationship between the ZT and RLN and SP are essential for performing safe thyroid surgery.