The Zuckerkandl tubercle: problematic or helpful in thyroid surgery?

Abstract

The Zuckerkandl tubercle is a residue from the embryological development of the thyroid gland. Although it is undeniably well known in surgery, this is not so among otolaryngologists. Our objective is to highlight the importance of the Zuckerkandl tubercle, as it has proven to be a reliable point of reference to locate the upper parathyroid, the lower thyroid artery and the recurrent nerve. In order to study the Zuckerkandl tubercle, we made a prospective analysis of the posterolateral border of the thyroid lobes in 107 thyroidectomies (88 total thyroidectomies and 19 hemithyroidectomies) carried out by the same surgeon; in total, 195 thyroid lobes were analysed. The Zuckerkandl tubercle was certainly detected in 155 thyroid lobes (79.48%). The Zuckerkandl tubercle was most frequent in the right thyroid lobe (P = 0.06). When the Zuckerkandl tubercle was present, we localised the upper parathyroid due to its relationship with the tubercle in 80 right thyroid lobes (95.23%) and in 65 left (91.54%). On 147 occasions (94.83%), the recurrent nerve was directed towards the cricothyroid membrane beneath the Zuckerkandl tubercle, laterally to the tracheal surface in relation with the Berry ligament. The lower thyroid artery and some of the distal branches, such as the recurrent nerve, also ran under the Zuckerkandl tubercle. The areolar tissue underlying the Zuckerkandl tubercle is difficult to dissect, and so this protuberance constitutes a surgical difficulty but it is fundamentally helpful to find those important structures that must be preserved in thyroid surgery.

Zuckerkandl Tubercle of the Thyroid Gland: Correlations between Findings of Anatomic Dissections and CT Imaging

“…The anatomic correlations of the ZT with the recurrent laryngeal nerve and the superior parathyroid gland were reported by Gilmour, 2 but this structure subsequently received little attention. Following the description of the ZT as a constant anatomic landmark of the recurrent laryngeal nerve and its classification into 4 grades according to its size, 3 the topographic anatomy of these structures and the grading of the ZT have been studied both in patients during surgery [4][5][6][7][8] and in cadavers. 9,10 ZT has mostly been defined as a pos-terior or lateral projection or a projection from the posterolateral border of the thyroid lobe in previous studies, but it was recently reported as a posteromedial projection in a normal anatomic position.…”

“…11 Most ZTs extend into the tracheoesophageal groove or posterior to the esophagus. 8,11 Failing to remove the ZT in its entirety during total thyroidectomy may result in persistent unrelieved symptoms or recurrence 4,12,13 as well as persistent radioiodine uptake on radioactive iodine scans. 7 An enlarged ZT may increase pressure symptoms.…”

Zuckerkandl's tubercle of the thyroid gland: Its location in the anatomical position, and comparative morphology of the same specimens before and after fixation

“…The ZT of the right thyroid lobe was previously reported to be larger than that of the left lobe (Mehanna et al, 2014), but the sizes were similar in the present study. The incidence of the ZT has generally been reported as within the range 60-80% (Pelizzo et al, 1998;Hisham and Aina, 2000;Gauger et al, 2001;Yalç yn and Ozan, 2007;Kaisha et al, 2011;Sheahan and Murphy, 2011;Gil-Carcedo et al, 2013;Mehanna et al, 2014), though there is one report of a very low incidence of 7% (Page et al, 2009). The ZT was classified by Pelizzo et al (1998) into four grades according to its size, from 0 to III (larger than 1 cm), but with no indication as to whether "size" meant the length of the base or the height of the structure.…”

“…In the present study, the length and height were Grade III in 82% and 17%, respectively, of fresh specimens, and in 71% and 9% of fixed specimens. The incidence of Grade III has been reported as approximately 14% (Pelizzo et al, 1998), 24% (Sheahan and Murphy, 2011), 37% (Yun et al, 2008), 45% (Gauger et al, 2001), 55% (Hisham and Aina, 2000), and 79% (Gil-Carcedo et al, 2013) in surgery-based studies, and 57% (Kaisha et al, 2011) in cadavers. This very wide range of incidences might be attributable to geographical or environmental factors, genetic or ethnic factors, or White-headed pins were stuck into the upper and lower margins of the ZT in the fresh specimen prior to fixation, and were used as reference markers for comparisons between the fresh and subsequently fixed specimens.…”

Predicting difficulty of thyroidectomy preoperatively

“…[15][16][17][18] Traditionally cited factors contributing to difficulty in thyroid surgery include increased vascularity, inflammation, friability, fibrosis, and large gland size. [19][20][21] The thyroid surgery literature includes numerous examples of each individual item that comprises the Thyroidectomy Difficulty Scale.…”