The relation of recurrent laryngeal nerve to inferior thyroid artery and extralaryngeal nerve branching may increase the risk of vocal cord paralysis in thyroidectomy.

PURPOSE: The anatomical variations of the recurrent laryngeal nerve (RLN) are common during thyroidectomy. We aimed to evaluate the risk of RLN paralysis in case of its anatomical variations, retrospectively. METHODS: The patients with primary thyroidectomy between January 2016 and December 2019 were enrolled. The effect of age, gender, surgical intervention, neuromonitorisation type, central neck dissection, postoperative diagnosis, neck side, extralaryngeal branching, non-RLN, relation of RLN to inferior thyroid artery (ITA), grade of Zuckerkandl tubercle on vocal cord paralysis (VCP) were investigated. RESULTS: This study enrolled 1070 neck sides. The extralaryngeal branching rate was 35.5%. 45.9% of RLNs were anterior and 44.5% were posterior to the ITA, and 9.6% were crossing between the branches of the ITA. The rate of total VCP was 4.8% (transient:4.5%, permanent: 0.3%). The rates of total and transient VCP were significantly higher in extralaryngeal branching nerves compared to nonbranching nerves (6.8% vs. 3.6%, p = 0.018; 6.8% vs. 3.2%, p = 0.006, respectively). Total VCP rates were 7.2%, 2.5%, and 2.9% in case of the RLN crossing anterior, posterior and between the branches of ITA, respectively (p = 0.003). The difference was also significant regarding the transient VCP rates (p = 0.004). Anterior crossing pattern increased the total and transient VCP rates 2.8 and 2.9 times, respectively. CONCLUSION: RLN crossing ITA anteriorly and RLN branching are frequent anatomical variations increasing the risk of VCP in thyroidectomy that cannot be predicted preoperatively. This study is the first one reporting that the relationship between RLN and ITA increased the risk of VCP.

A meta-analysis: elucidating diagnostic thresholds of peak systolic flow velocities in thyroid arteries for the discrimination of Graves' disease and destructive thyrotoxicosis.

Objective: This meta-analysis examines peak systolic velocities (PSVs) in thyroid arteries as potential biomarkers for thyroid disorders, which includes treated and untreated Graves' disease(GD) and destructive thyrotoxicosis(DT). Methods: A search across databases including PubMed, Google Scholar, Embase, and Web of Science identified studies assessing peak systolic flow velocity in the inferior thyroid artery (ITA-PSV) and superior thyroid artery (STA-PSV) diagnostic efficacy in GD and DT.And the search was restricted to publications in the English language.The analysis compared STA-PSV and ITA-PSV across patient groups, evaluating intra-group variances and synthesizing sensitivity and specificity data. Results: The analysis covered 18 studies with 1276 GD, 564 DT patients, and 544 controls. The difference of STA-PSV between GD group, DT group and normal group and the difference of ITA-PSV were analyzed in subgroups, and there was no statistical significance between subgroups when comparing any two groups. Normal subjects displayed intra-group ITA-PSV and STA-PSV differences with established cut-off values of 20.33 cm/s (95% CI, 17.48-23.18) for ITA-PSV and 25.61 cm/s (95% CI, 20.37-30.85) for STA-PSV. However, no significant intra-group differences were observed in the STA-PSV and ITA-PSV cut-off values among groups with GD or DT. The combined cut-off values for these patient groups and normal subjects were 68.63 cm/s (95% CI, 59.12-78.13), 32.08 cm/s (95% CI, 25.90-38.27), and 23.18 cm/s (95% CI, 20.09-26.28), respectively. The diagnostic odds ratio(DOR) for these values was 35.86 (95% CI, 18.21-70.60), and the area under the summary receiver operating characteristic (SROC) curve was 0.91, with a sensitivity estimate of 0.842 (95% CI, 0.772-0.866). Conclusion: PSVs in thyroid arteries are useful diagnostic tools in distinguishing DT from GD. A PSV above 68.63 cm/s significantly improves GD diagnosis with up to 91% efficacy. No notable differences were found between superior and inferior thyroid arteries in these conditions.

An ectopic thyrolingual trunk arising from the common carotid artery: a rare variant.

The common carotid artery (CCA) typically bifurcates into the external and internal carotid arteries (ECA and ICA). In the head and neck area, the ECA gives off a few anterior branches from proximal to distal: the superior thyroid artery (STA), the lingual artery (LA), and the facial artery (FA). Occasionally, these branches can fuse into trunks, with the linguofacial trunk being the most common. During a computed tomography angiography (CTA) of a 67-year-old patient, a common arterial trunk, 11.3 mm proximal (prior) to the CCA bifurcation was recorded. The trunk was formed by the STA and the LA fusion and was characterized as a thyrolingual trunk (TLT). These trunks have been reported with a prevalence ranging between 0.3 and 1% and correspond to one of the rarest variants of the ECA anterior branches. Knowledge of the typical and variant anatomy of the carotid arteries and their branches is of paramount importance to surgeons and interventional radiologists.

Superior laryngeal artery originating from the lingual artery.

In most cases, the superior laryngeal artery (SLA) branches from the superior thyroid artery, which, in turn, leaves the external carotid artery. Few dissection studies found previously that the SLA could originate from the lingual artery. We report here probably the first evidence of such a rare anatomical variation found unilaterally in a retrospectively evaluated by computed tomography angiography adult male case. The left SLA left a suprahyoid coil of the lingual artery and continued over the greater hyoid horn to enter the larynx through the thyrohyoid membrane. On both sides, thyroid foramina were found, but only the right one used for the entry of the right SLA. Therefore, the rare SLA origin from the lingual artery can be documented on computed tomography angiograms, which could help during preoperative evaluations and prevent unwanted surgical complications.

Considerations on the morphology of the thyroid ima artery.

PURPOSE AND BACKGROUND: Detailed knowledge of the thyroid ima artery is essential for surgeons consequently we conducted an analysis investigating the arterial vasculature of the thyroid gland in 290 cases by dissection of formalin-fixed cadavers and by studying computed tomography angiographies. METHODS: Our study was conducted on 82 cases obtained from the dissection of formalin-fixed cadavers while 208 cases were computed tomography angiographies. The following aspects were observed: the frequency of the thyroid ima artery, its origin, course, and diameter. All were studied, comparing right to left and according to sex. RESULTS: Following the study of thyroid gland vasculature on a number of 290 cases, the thyroid ima artery was discovered in 16 cases (5.52% of cases), from which 3.45% of cases were in male subjects, and 2.07% of cases in female subjects. Of these, 4.14% of the total cases were left thyroid ima artery, and 1.38% of cases were on the right, found only in female subjects. In 5.17% of the total cases, the thyroid ima artery originated from the aortic arch, of which 3.45% were in the male sex and 1.72% were in the female sex. In one case only (0.35%) in the female sex did the thyroid ima artery originate from the brachiocephalic trunk. In 2.76% of cases, the thyroid ima artery existed with a left-sided inferior thyroid artery originating from the subclavian artery, either directly or from a thyrocervical trunk. CONCLUSIONS: The thyroid ima artery has proven to be one of the highly variable arteries in terms of its presence and origin and the knowledge surrounding it is useful for surgical interventions.

Is the origin of the superior thyroid artery consistent? A systematic review of 5488 specimens.

PURPOSE: The superior thyroid artery (STA) point of origin is strongly debated with controversial results among studies. External carotid artery (ECA), carotid bulb, and common carotid artery (CCA) have been presented as points of origin with variable percentages among authors. We conducted a systematic review of all existing studies that included cadaveric, surgical, and angiographic specimens and recorded the origin of STA according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. MATERIALS AND METHODS: Fifty-two studies, with an overall of 5488 specimens were included. RESULTS: Our results indicated ECA as the most common site of origin (55.0 %) followed by carotid bifurcation at 27.5 % and CCA at 15.0 %. Absent STA or branching from the internal carotid artery (ICA) was an extremely rare finding. We proposed a new simple classification system based on our results. CONCLUSIONS: The huge variability in the branching pattern of STA makes head and neck surgery and radiographic interventions challenging and poses the integrity of STA at risk. Therefore, we strongly recommend preoperative angiographic studies for STA identification to prevent an intraoperative iatrogenic injury.

Considerations on the origin of the inferior thyroid artery emerging from the subclavian artery determined by CT examination.

PURPOSE AND BACKGROUND: The specialized literature has a low degree of information regarding the origin of the inferior thyroid artery (ITA). Our study was performed on computed tomography angiographies (CTAs), and the following aspects were observed: the origin of the ITA from the subclavian artery (SCA) or thyrocervical trunk (TCT), taking note of the distance of the origin of the ITA in relation to the origin of the SCA or the corresponding TCT, as well as the origin of the ITA, comparing right to left and according to gender. METHODS: Our study was realized on a total of 108 ITA (64 on the right side and 44 on the left, with 48 in male subjects and 60 in females), analyzed on CTA. RESULTS: From the 108 arteries, we found the origin of ITA directly from the SCA in 31.48% of cases, and in 68.52% from the TCT. The distance between the origin of the right SCA and the origin of the corresponding ITA, was between 29.1 and 53.1 mm, while on the left side, the same distance was between 43.7 and 68.1 mm. The distance between the right TCT and the origin of the right SCA, was between 22.5 and 75.0 mm, and for the left side, it's between 48.7 and 56.8 mm. CONCLUSIONS: The inferior thyroid artery is one of the arteries most susceptible to variations in terms of origin and size. With differences between the two sides (right and left), as well as differences related to gender.

Anatomical variations of the superior thyroid artery: A systematic review.

BACKGROUND: The superior thyroid artery (STA) is one of the main arteries that provide blood supply to the thyroid gland. It has a plethora of anatomical variations, and knowledge of its anatomy is necessary in procedures in this area. The aim of this review is to summarize and describe human studies (cadaveric and angiographic) that investigate the anatomical variations related to the STA. MATERIAL AND METHODS: A systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. A literature search in PubMed, and Embase databases was carried out. Original studies that investigated the origin of the STA and reported data on the variant arterial anatomy were considered, including only cadaveric and angiographic studies. RESULTS: A total of 34 studies (4048 heminecks in total; heminecks in each study: min: 25-max: 1280) were finally included. All studies provide details about sex [men/women ratio median (IQR): 2(1-5)] but none about age and 10 (29%) about nationality. STA morphological characteristics described in the included studies are origin, length, number of branches, distance from the carotid bifurcation and the vessel's diameter. CONCLUSIONS: The STA's anatomical features are subject to a non-negligible degree of variability. Our results should improve the awareness of anatomical variations of the STA, and eventually have an impact on the interventions regarding the visceral compartment of the neck in clinical practice.

Topographic anatomy and vascularization of the glandula thyroidea in rats.

Topographical anatomy and detailed measurements of the glandula thyroidea (thyroid gland) and the glandula parathyroidea (parathyroid gland) were determined in rats, with significant differences identified between the sexes. In the rats (N = 10 male, 10 female), the glandula thyroidea were positioned at the level of the C1 and C2 vertebrae. One glandula parathyroidea was present in each glandula thyroidea lobe, localized in the cranial part of the lateral lobes in 60% of the animals. There was no glandula thyroidea left lobe in one female and no isthmus in two females. Both the A. thyroidea cranialis and the A. pharyngea ascendens originated from the A. carotis externa, which acted as a common trunk. On the left, the A. thyroidea caudalis originated from the truncus brachiocephalicus in all rats and on the right side was found to originate from both the truncus costocervicalis and the A. subclavia dextra in three females, and only from the truncus costocervicalis in seven females. The V. thyroidea cranialis opened into the V. jugularis interna in the neck region and at the level of the apertura thoracis cranialis, and the V. jugularis interna united with the V. thyroidea caudalis. In addition, on the right, the V. thyroidea cranialis joined the V. jugularis interna, at the level of the A. subclavia. The veins on both sides opened into the V. cava cranialis. Significant differences were observed between the sexes and detailed anatomical analysis of the glandula thyroidea and the glandula parathyroidea, and related vasculature and innervation, have been described in this paper.

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.

A Computational Template for Three-Dimensional Modeling of the Vascular Scaffold of the Human Thyroid Gland.

We recently designed an innovative scaffold-bioreactor unit for the bioengineering of a three-dimensional (3D) bioartificial human thyroid gland or its miniaturized replica as a part of a microfluidic chip test system. This device is based on the evidence that the 3D geometry of the intraglandular stromal/vascular scaffold (SVS; i.e., the fibrous and vascular matrix) of mammalian viscera plays a key role in guiding growth and differentiation of in vitro seeded cells. Therefore, we initiated a research program focused on computer-aided reconstruction of the 2nd to 4th order intralobar arterial network (IAN) of the human thyroid gland as a reliable surrogate for its 3D SVS, to be used as an input for rapid prototyping of a biomaterial replica. To this end, we developed a computational template that works within the Mathematica environment, giving rise to a quasi-fractal growth of the IAN distribution, constrained within an approximation of the thyroid lobe shape as a closed surface. Starting from edge detection of planar images of real human thyroid lobes acquired by in vivo real-time ultrasonography, we performed data approximation of the lobar profiles based on splines and Bezier curves, providing 3D lobar shapes as geometric boundaries for vessel growth by a diffusion-limited aggregation model. Our numerical procedures allowed for a robust connection between development of lobar arterial trees and thyroid lobe shape, led to a vascular self-similarity consistent with that of a cadaveric lobar arterial cast, and reproduced arterial vessels in a proportion not statistically different from that described for the real human thyroid gland. We conclude that our algorithmic template offers a reliable reproduction of the extremely complex IAN of the adult human thyroid lobe, potentially useful as a computational guidance for bioprinting of thyroid lobe matrix replicas. In addition, due to the simplicity and limited number of morphometrical parameters required by our system, we predict its application to the design of a number of patient-tailored human bioartificial organs and organs-on-chip, including parenchymal viscera and bones. Impact statement The study introduces the computer simulation of the three-dimensional (3D) intrinsic vascular matrix of the human thyroid gland, offering a general concept applicable to a number of other human viscera. Indeed, it provides a flexible software tool for reproduction of a 3D surrogate of the organ's 3D stromal matrix, suitable for eventual 3D bioprinting with biomaterials, and recellularization with organ-specific stem cells/progenitors. The final expectation is the design of patient-tailored 3D organ's matrices upon clinical request.

Triple variation in the vascular supply in the neck of a female donor body: a case report.

PURPOSE: Understanding the anatomical variations involving bifurcation of the common carotid artery, positioning of external and internal carotid arteries, and branching of the external carotid artery are of vital importance in neck surgeries such as carotid endarterectomies (CEA). METHODS: The neck of a 51-year-old female donor body was dissected to demonstrate the arterial network. RESULTS: Bifurcation of the common carotid artery occurred at the level of the C6-C7 intervertebral disc, significantly inferior to the generally accepted and taught anatomical location at the level of intervertebral disc between C3 and C4 vertebrae. When the arteries were followed superiorly after the bifurcation, a unique second variation was observed: translocation of the external and internal carotid arteries. The external carotid artery was located posterolaterally and the internal carotid artery was located more medially. Finally, a third variation was discovered in the form of a common thyrolingual trunk that gave rise to superior thyroid and lingual arteries rather than these arising independently from the external carotid artery. CONCLUSIONS: We report a unique triple variation within the major arteries of the neck that has not been previously reported in surveyed literature. This case report may provide useful information for cardiovascular surgeons performing CEA and for otolaryngologists performing prophylactic arterial ligation following transoral robotic surgery for oropharyngeal cancer resection.

Combined unusual origin and course of the right vertebral artery and right inferior thyroid artery: a case report.

PURPOSE: An unusual unilateral origin and course of the prevertebral part of the right vertebral artery and anomalous course of the right inferior thyroid artery was observed during dissection of the neck of a cadaver. METHODS: An accidental finding in the cadaver within the anatomical dissection was assessed. RESULTS: The right vertebral artery originated a nonstandard from brachiocephalic trunk and travelled in the anterior cervical region, along the longus colli muscle in front of the transverse processes from C7 to C4, and it entered the transverse foramen of C3. During its course, the position of the right inferior thyroid artery varied: it turned medially and passed posterior to the vertebral vessels and later curved inferomedially to its termination. Additionally, the left vertebral artery of the same cadaver arose directly from the subclavian artery and entered the transverse foramen at C6, and the left inferior thyroid artery passed anterior to the vertebral artery. CONCLUSION: Variation in the vertebral artery and inferior thyroid artery alone have been reported, but a combined variation is rare. The anatomical information from this study will be useful during dissection, angiography, endovascular surgery, thyroidectomy and non-invasive procedures in the cervical region.

Common trunk of the internal thoracic artery, inferior thyroid artery and thyrocervical trunk from the subclavian artery: a rare arterial variant.

PURPOSE: In this article, we describe a complex and rare variant of the common trunk arising as a branch of the subclavian artery. This description highlights the clinical relevance of such a variation for medical practice. METHODS: A routine dissection was carried out on an adult 74-year-old female cadaver. After identification and preparation of the common trunk, measurements and photographs were taken. RESULTS: The dissection revealed a common trunk arising from the first part of the left subclavian artery. It divided into the left internal thoracic artery, the inferior thyroid artery, and the thyrocervical trunk. Further on, the branches of the thyrocervical trunk supplied blood to the trapezius muscle, the longus colli muscle and the supraspinatus muscle. CONCLUSION: For the first time, we report the specific appearance of a common trunk from the left subclavian artery that includes the origin of the left internal thoracic artery, inferior thyroid artery, and thyrocervical trunk. Knowledge of the different variations of subclavian branches is essential because of the high frequency with which this region is involved in diagnostic and surgical procedures. LEVEL OF EVIDENCE: II Basic Science Research.

Analysis of vascularization in thyroid gland nodes with superb microvascular imaging (SMI) and CD34 expression histology: a pilot study.

BACKGROUND: The Doppler sonography technique known as "superb microvascular imaging" (SMI) is advancing sonographic micro vascularization imaging in various disciplines. In this study, we aimed to determine whether SMI could reliably reproduce the blood flow in thyroid nodes and whether malignancy could be diagnosed, based on vascularization properties. Immunhistochemical staining by CD34 and SMI where used to determine the vascularization of nodes in terms of quantified vascularization parameters gained by computational evaluation. METHODS: We used image analysis programs to investigate whether the quantitative value for vascularization strength in the thyroid node, measured with SMI, was correlated with the actual degree of vascularization, determined microscopically. We included 16 patients that underwent thyroid resections. We prepared thyroid gland tissue slices for immunohistochemistry and labelled endothelial cells with CD34 to visualize blood vessels microscopically. We used image analysis programs, ImageJ, to quantify SMI Doppler sonographic measurements and CellProfiler to quantify CD34 expression in histological sections. We evaluated the numeric values for diagnostic value in node differentiation. Furthermore, we compared these values to check for correlations. RESULTS: Among the 16 nodes studied, three harboured malignant tumours (18.75%): two papillary and one follicular carcinoma. Among the 13 benign lesions (81.25%), four harboured follicular adenomas. Malignant and benign nodes were not significantly different in sonographic (0.88 ± 0.89 vs. 1.13 ± 0.19; p = 0.2790) or immunohistochemical measurements of vascularization strength (0.05 ± 0.05 vs. 0.08 ± 0.06; p = 0.2260). CONCLUSION: We found a positive, significant correlation (r = 0.55588; p = 0.0254) between SMI (quantitative values for vascularization strength) and immunohistochemistry (CD34 staining) evaluations of thyroid nodes.