Zuckerkandl's tubercle and its relationship to the recurrent laryngeal nerve: A cadaveric dissection and meta-analysis

Identification of valid anatomical landmarks to locate and protect recurrent laryngeal nerve during thyroid surgery: a cadaveric study

PURPOSE

Recurrent laryngeal nerve (RLN) is the most critical structure in terms of intricacy. Anatomic variations of the nerve may further make thyroid surgery cumbersome. The present study was undertaken to provide comprehensive knowledge about the soundness of commonly used anatomical landmarks such as Berry's ligament (BL), tracheo-esophageal groove (TEG), inferior thyroid artery (ITA), and the midpoint of the posterior border of the thyroid gland in the identification of the nerve intraoperatively.

METHODS

Thirty adult cadavers were dissected to identify the RLN in the neck and to locate it in relation to the aforementioned anatomical landmarks.

RESULTS

The RLN/BL relationship: RLN was most often located superficial to the BL (88.3%), followed by deep to the BL in 8.4%, and piercing the BL in 3.3% of cases, respectively. The RLN/TEG relationship: the RLN was located inside the TEG in most cases (71.7%), followed by RLN lying outside the TEG in 28.3%. Outside the groove, it was most commonly found lateral to the TEG (64.7%). RLN/ITA relationship: the nerve was passing deep to the artery in most of the cases (65%), followed by superficial (30%) and rarely (5%) in-between the branches. RLN/ midpoint posterior border of thyroid relationship: In 57 (95%) cases, RLN was coursing in the area posterior to the midpoint of the posterior border of the gland with an average distance of 4.95 ± 2.23 mm ranging between 2.21 and 12.1 mm.

CONCLUSIONS

Both the BL and TEG are potentially crucial for safeguarding RLN. Although in results, BL turns out to be more consistent than TEG, we propose the utilization of both these anatomical landmarks together for complication-free neck surgeries. Furthermore, the midpoint of the posterior border of the thyroid turns out to be the single most consistent landmark for identifying RLN during partial thyroidectomy.

Comparative Study of Parathyroid Identification Techniques Using Zuckerkandl's Tubercle Versus Parathyroid Arterial Supply as Intra-Operative Markers

Thyroid surgeons should be able to identify factors that prevent parathyroid damage. The aim of the study was (i) to compare the effectiveness of using Zuckerkandl's Tubercle (ZT) versus superior thyroid artery (STA) and inferior parathyroid artery (ITA) as markers for identification of superior and inferior parathyroid glands and (ii) to demonstrate a series of detailed, logical and orderly operative steps to identify ZT during thyroidectomy operation. This 1-year prospective observational study was carried out in the Department of Otolaryngology in a tertiary medical institute. Out of 36 cases of thyroidectomy, parathyroid identification in Group A was based on STA and ITA and in Group B was based on ZT. The surgical steps, parathyroid location, preservation and its anatomical relations were noted. The mean age in Group A and Group B was 38.8 years and 44.9 years respectively with 77.4 and 62.5% SPT identified above the intersection of RLN and ITA respectively. On left side 62.5% SPT were  located at 2 o'clock position and 50% at 10 o'clock location in right side. In Group A, 60.7% of IPT glands were related close to ITA while in Group B it was 44.4%. Group B reported a higher rate of successful identification and preservation (93.75%). ZT greatly improved the reliability for localising and preserving the parathyroid glands during thyroidectomy. SPT is usually found to lie cranial to ZT, above the intersection of RLN & ITA and behind RLN whereas IPT is variable and lies below the intersection.

Relation of Nonrecurrent Laryngeal Nerve with Zuckerkandl's Tubercle

The nonrecurrent laryngeal nerve (NRLN) is a rare anatomical variation of the recurrent laryngeal nerve (RLN) that may hinder the identification and preservation of this nerve during surgery and is associated with increased iatrogenic risks. Zuckerkandl's tubercle (ZT) is considered a useful reference for locating the RLN during thyroid surgery. We report the case of an asymptomatic patient with a 23 mm uninodular goitre suspicious for cancer. Ultrasound examination showed a hypoechoic nodule with regular contours and microcalcifications. The patient had normal thyroid-stimulating hormone and thyroxine levels, and aspiration biopsy was suspicious for follicular cancer. She was treated with total thyroidectomy after the intraoperative examination confirmed the presence of a papillary thyroid carcinoma. The standard approach to the RLN below the inferior thyroid artery was used on both sides. The nerve displayed anatomical variation in the nonrecurrent form (NRLN) on the right side and was associated with another variation that was not found in the consulted literature. It was completely surrounded by thyroid tissue in the region of ZT, and the surgeon was forced to remove it from within the thyroid tissue. This combination of anatomical variations seems to be quite rare. Knowledge of the anatomy of the RLN and its variations, as well as its identification and careful dissection, is essential to avoid injury to the nerve during surgical procedures.

Extended Surgical Implication of Tubercle of Zuckerkandl in Total Thyroidectomy

The primary objective of the study was to assess the Tubercle of zuckerkandl (TZ) during thyroid surgeries and its relationship with RLN and Superior parathyroid (SP). A prospective study was done in, 30 consecutive cases of total thyroidectomy in whom per operatively TZ was identified. The presence of TZ, its laterality, size, relationship with RLN and parathyroid glands were documented. A grading system outlined by Pelizzo was applied in our current study. In majority of the cases the RLN was found to lie medial to TZ (26/30), followed by lateral position (3/30) and one case it was found to be posterior to TZ (1/30). The superior parathyroid was identified in close relation (< 2 cm) to the TZ in 27/30 cases. The distance between the TZ and SP was assessed. We proposed a classification for location of SP based on the distance between SP and TZ and also attempted to relate each class of SP location with TZ grade. There was strong association of Grade of TZ with the class of SP location (p value = 0.00046). TZ is constant surgical landmark with good reliability to identify the RLN and SP. RLN is found medial to TZ in majority of cases with few exceptions. SP is found to be closely associated with TZ in majority of cases and there is a strong relationship of proximity of SP and TZ with respect to TZ grade. Although this required further studies with larger population.

Can the Zuckerkandl tubercle assist in the location of the inferior laryngeal nerve during thyroidectomies?

OBJECTIVE

to evaluate whether the lateral projection of the thyroid gland, called Zuckerkandl's tubercle (ZT), can assist the surgeon in identifying the inferior laryngeal nerve during conventional open thyroidectomy.

METHODS

we conducted a prospective study with 51 patients submitted to thyroidectomy, with a total of 100 resected thyroid lobes, and observed the presence or absence of ZT in sufficient dimensions to be identified without image magnification, its base and height, its location in the gland, and its anatomical relationship with the inferior laryngeal nerve.

RESULTS

ZT was present in 68 of the 100 thyroid lobes analyzed (68%). The mean base was 6.7mm on the right side and 7.1mm on the left side, and the average height was 5.7mm on the right side and 6.1mm on the left side. In most of the lobes studied, the tubercle had a minimum height of 5mm (55.9%), with no significant difference between the right and left lobes of the thyroid gland. During surgery, 100% of the identified ZTs were anterior to the inferior laryngeal nerve, just below the nerve entry in the larynx.

CONCLUSION

the ZT is a quite frequent entity and large enough to serve as an intraoperative anatomical reference for the inferior laryngeal nerve, next to its entry in the larynx, along with other anatomical references.