The Tubercle of Zuckerkandl : An Important Landmark Revisited

The use of Zuckerkandl's tubercle as an anatomical landmark in identifying recurrent laryngeal nerve and superior parathyroid gland during total thyroidectomy: a prospective single-surgeon study

Objective

To determine the incidence and characteristics of Zuckerkandl's tubercle (ZT), and its relationship with recurrent laryngeal nerve (RLN) and the superior parathyroid gland (SPG) in the setting of total thyroidectomy.

Methods

A total of 421 patients (mean (min-max) age: 45.6 (18-78) years, 76.2% were females) who had total thyroidectomy were included in this prospective single-surgeon thyroidectomy series study. Patient demographics and thyroidectomy indications (benign and malignant) were recorded in each patient. The presence, grade and laterality of ZT, and its relationship with RLN and SPG were recorded during surgery.

Results

Most of the thyroidectomy indications (69.1%) were related to a malignant disease. The ZT was unrecognizable in 41(9.7%) of 421 patients. In 380 patients with identifiable ZT, the grade 2 (46.3%) ZT was the most common finding. Majority of ZTs (92.9%) were unilaterally located (right-sided: 64.9%; left-sided: 35.1%). In majority of the cases (83.2%), the RLN was found to lie medial to ZT. Overall, SPG was identified in close proximity to ZT in 66.6% of patients (Class 2 [0.5-1 cm from ZT] in 46.6% and Class 3 [<0.5 cm from ZT] in 20.0%). SPG was more likely to be identified in close proximity to ZT when the grade of ZT was higher, which was found to be located 0.5-1 cm from the ZT in 56.9% and 42.7% of grade 2 and grade 3 ZTs, respectively, and <0.5 cm from the ZT in 46.1% of grade 3 ZTs.

Conclusion

In conclusion, this prospective single-surgeon thyroidectomy series study indicates the likelihood of localizing the RLN medial to ZT, and the SPG in close proximity to ZT during total thyroidectomy operations. Hence, the ZT can be used as a reliable and constant landmark to localize both the RLN and the SPG during thyroid surgery, which enables minimizing the risk of iatrogenic injury to RLN, while ensuring a parathyroid-sparing thyroidectomy. The thyroid surgeon should have complete knowledge of thyroid gland anatomy and embryogenesis and should follow a careful and meticulous approach particularly for dissections around larger ZTs, given the increased likelihood of SPG and RLN to be in close proximity.

Relationship of Recurrent Laryngeal Nerve with Inferior Horn of Thyroid Cartilage, Berry's Ligament and Zuckerkandl's Tubercle

During neck surgery; Zuckerkandl's tubercle, Berry's ligament, the inferior horn of thyroid cartilages have become crucial anatomical landmarks in order to protect the integrity of the recurrent laryngeal nerve. Forty-two male postmortem human cadavers were used. The proximal part of the recurrent laryngeal nerve, before the inferior thyroid artery arises from its source has been observed in 87% inside the tracheoesophageal groove and in 13% running laterally to the trachea. The recurrent laryngeal nerve was encountered passing behind and through the branches of the inferior thyroid artery in 92% and 8% respectively. At all sides; the nerve was piercing the larynx 0.6 ± 0.1 mm below the inferior horn of thyroid cartilage, passing next to the inner-lower side of Berry's ligament and running under the lower middle part of Zuckerkandl's tubercle. These landmarks and their upper mentioned distances to the laryngeal nerve can be taken into consideration as important surgical guides.

The parietal foramen anatomy: studies using dry skulls, cadaver and in vivo MRI

OBJECTIVE

The aim of this study was to describe the anatomical features encountered in the parietal foramen in a series of 178 human bones and 123 head MRI examinations. A cadaveric specimen was also dissected to demonstrate the trajectory of a superficial scalp vein through the parietal foramen as far as the dura mater. A literature review was performed regarding prevalence of parietal foramen in different populations.

METHODS

Totally, 178 paired adult bones were used to investigate the presence, shape and number of the parietal foramina. In addition, 123 brain MRI examinations were also studied.

RESULTS

The parietal foramina were encountered in 75/89 (84.3%) skulls [32/38 (84.2%) in women vs. 43/51 (84.3%) in men, p > 0.05]. The parietal foramen was present bilaterally in 44.73% of females and 54.9% of males. Regarding unilaterality of the parietal foramen, a right or left laterality was observed in female 21% right versus 18% left; and 16% versus 14% (left) in males (p > 0.05). The accessory parietal foramen was present in the right parietal in 2.6% and in 7.9% on the left side of the females, while 5.9% and 3.9% of the males on the right or left sides, respectively. The parietal foramina located in the proximity of the sagittal suture (male 7.1 ± 2.5 mm vs. female, 7.4 ± 2.7 mm). There was a positive correlation between the right and left parietal foramina regarding the distance from the median line. The distance from a foramen to the contralateral one was 16 ± 4 mm in men and 18 ± 5 mm in women, respectively (p > 0.05).

CONCLUSION

No major differences were encountered between sexes regarding the anatomical features of parietal foramen.

Thyroid Tubercle of Zuckerkandl May Not Arise from the Ultimobranchial Body: Results from Histological Analysis

Thyroid tubercle of Zuckerkandl (TZ) is a nodule arising from the posterolateral thyroid, considered to be a remnant of the ultimobranchial body (UB). Considering that C cells and solid cell nests also arise from the UB, we hypothesized that these would be present in the TZ. We examined the presence of C cells and solid cell nests in the TZ using the histological analyses of 21 patients with grade 2 or 3 TZs following Pelizzo's grading system. Out of 21 TZs, 19 (90.5%) were located in the right lobe of the thyroid. Microscopically, solid cell nests were found within the TZ in 1 case (4.8%), and within the main thyroid tissues in 3 cases (14.3%). Calcitonin-positive C cells were scattered within the TZ in 1 case (4.8%), and within the main thyroid tissue in 15 cases (71.4%). The distribution of C cells within the main thyroid tissue was denser than that within the TZ. The above-mentioned results indicated the lack of C cells and solid cell nests in the TZ. Although the TZ may have an embryological origin different from that of ordinary thyroid tissue, it is unlikely that the remnants of the UB are involved in the formation of the TZ.

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.

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

OBJECTIVE

Zuckerkandl's tubercle (ZT), when present, is an anatomical landmark by which surrounding structures such as the recurrent laryngeal nerve (RLN) can be identified intraoperatively. This study aimed to investigate the prevalence and anatomical characteristics of Zuckerkandl's tubercle by combining cadaveric dissection with a meta-analysis.

METHODS

Through October 2016, an extensive search of PubMed, CNKI, ScienceDirect, EMBASE, BIOSIS, SciELO, and Web of Science was completed. Extracted data, along with the findings from our cadaveric dissections, were pooled into a meta-analysis to assess the prevalence and size of ZT and its relationship to the RLN.

RESULTS

The pooled prevalence estimate of a ZT was 70.2% in the general population, 65.0% of which were considered Grade 0 tubercles (<1.0cm) and 35.0% Grade 1 (≥1.0cm). The RLN ran posteromedially to the ZT in 82.7% of cases, laterally to it in 8.7%, and on top of it in 8.6% of hemilarynges.

CONCLUSION

RLN palsy is a common postoperative complication and cause for litigation following neck surgery. The ZT is a common component of the thyroid gland and with proper knowledge, surgeons can use it to reliably and quickly identify the RLN during operative procedures.