Anatomic mapping of the collateral branches of the external carotid artery with regard to daily clinical practice

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.

The Diversity of the Linguofacial Trunk

Background and Objectives: Typically, the external carotid artery (ECA) sends off separate anterior branches: the superior thyroid, lingual, and facial arteries. These could, however, form common trunks: thyrolinguofacial, linguofacial (LFT), or thyrolingual. Although known, the LFT variant was poorly detailed previously, and most authors just counted the variant. We aimed to demonstrate the individual anatomical possibilities of the LFT on a case-by-case basis. Materials and Methods: 150 archived angioCT files were used. After applying inclusion and exclusion criteria, 147 files of 86 males and 61 females were kept for this study. Results: In 34/147 cases, LFTs were found (23.12%). Bilateral LFTs were found in 13/34 cases (38.24%) and unilateral LFTs in 21/34 (61.76%) cases. Forty-seven LFTs were thus identified and further studied for different variables. Regarding the vertical topography of LFT origin, type 1a (suprahyoid and infragonial) was found in 28 LFTs (59.57%), type 1b (suprahyoid and gonial) was found in eight LFTs (17.02%), type 3 (suprahyoid and supragonial) was found in two LFTs (4.25%), type 2 (hyoid level of origin) in eight LFTs (17.02%), and type 3 (infrahyoid origin) in just one LFT (2.12%). Types of the initial course of the LFT were determined: type I, ascending, was found in 22/47 LFTs; type II, descending, in 12/47 LFTs; and type III, transverse, in 13/47 LFTs. Regarding the orientation of the first loop of the LFT, 23/47 LFTs had no loop, 4/47 had anterior loops, 1/47 had a posterior loop, 5/47 had superior loops, 5/47 had inferior loops, and 9/47 had medial loops. The position of the LFT relative to the ECA was classified as medial, anterior, or antero-medial. An amount of 12/47 LFTs were anterior to the ECA, 22/47 were antero-medial, 10/47 were medial, 2/47 were inferior, and 1/47 was lateral. Regarding their general morphology, 23/47 LFTs had a rectilinear course, 22/47 had loops, and 2/47 were coiled. A case-by-case presentation of results further demonstrated the diversity of the LFT. Conclusions: In conclusion, the morphology and topography of the LFT are individually specific and unpredictable. It can be anticipated case-by-case by surgeons on CT or MR angiograms.

Lingual and Facial Artery Fusion: A Cadaveric Report With Clinical Significance

The external carotid artery (ECA) anterior branches, including the superior thyroid, the lingual, and the facial artery (STA, LA, and FA) present variability among cadaveric studies. These arteries may usually originate as isolated branches from the ECA anterior surface and atypically migrate proximally or distally and/or fused into trunks with the most common fusion that of the LA with the FA, into the linguofacial trunk (LFT), and the rarer ones those of the thyrolingual and thyrolinguofacial trunks. The current report describes a case of a bilateral fusion of the LA with the FA into an LFT and another case of a unilateral origin of the FA from the LA (aberrant FA).  In a 75-year-old donated male cadaver, a bilateral symmetrical LFT coexisted with a right-sided STA origin from the ECA proximal origin, at the level of the common carotid artery (CCA) bifurcation. In an 82-year-old donated female cadaver, at the left side, the atypical origin of the FA from the LA proximal origin coexisted with a common trunk of the left CCA with the brachiocephalic artery, and an atypical origin of the STA from the CCA, 3.65 mm inferior to the CCA bifurcation. This report provides a detailed description of the abnormal origin of the ECA anterior branches, the potential fusion of these branches, their exact location, and the existence of an unusual origin proximal or distal to the CCA bifurcation. Aberrant origin and course remain important in surgical and interventional approaches. A thorough understanding of the typical and variable anatomy of the ECA anterior branches ensures safe and successful intervention. Careful preoperative staging and precise dissection are essential components of this process.

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.

Morphometric Study and Branching Patterns of External Carotid Artery Using Computed Tomography Angiography Among the South Indian Population: A Retrospective Study

INTRODUCTION

The prime source of vascularization to the head and neck region is through the carotid arteries. The terminal branches of common carotid arteries, such as external carotid artery (ECA) and internal carotid artery (ICA), and their branches are crucial due to the wide area of distribution and variations in their branching pattern. The branching pattern and morphometry are essential for surgeons in the planning and execution of head and neck surgeries. Therefore, this study was conducted to observe the branching patterns of ECA and analyze them morphometrically.

MATERIALS AND METHODS

This retrospective study includes 100 CT images, inclusive of 32 females and 68 males. The branching pattern and luminal diameter of CCA and ECA were measured and analyzed statistically.

RESULTS

The luminal diameter of CCA in males were as follows: 7.4 ± 1.01 (R), 7.1 ± 0.8 (L), and in females: 7.3 ± 0.9 (R), 7 ± 0.9mm (L); and the luminal diameter of ECA in males: 5.2 ± 1.0mm (R), 5.2 ± 0.9mm (L), and in females: 5.0 ± 0.9mm (R), 5.1 ± 1.0mm (L). The level of the carotid bifurcation and ECA branching pattern was observed, and variations were commonly seen in the superior thyroid artery (STA), lingual artery (LA), and facial artery (FA).  Conclusion: The findings of the present study with regard to the external carotid artery and its branching pattern correlate with previous studies. The most common variations were observed in the superior thyroid and lingual and facial arteries. Knowledge about the morphology and branching pattern of the carotid artery is essential for procedures such as intra-arterial chemotherapy, carotid artery stenting, endarterectomy, and extra-intra cranial bypass revascularization procedure where it is harvested as a donor's vessel.

Vertical Levels of the Occipital Artery Origin

Background and Objectives. The occipital artery (OA) is a posterior branch of the external carotid artery (ECA). The origin of the OA is commonly referred to a single landmark. We hypothesized that the origin of the OA could be variable as referred to the hyoid bone and the gonial angle. We thus aimed at patterning the vertical topographic possibilities of the OA origin. Materials and Methods. One hundred archived computed tomography angiograms were randomly selected, inclusion and exclusion criteria were applied, and 90 files were kept (53 males, 37 females). The cases were documented bilaterally for different levels of origin of the OA origin: type 1-infrahyoid; type 2-hyoid; 3-infragonial; 4-gonial; 5-supragonial; 6-origin from the internal carotid artery (ICA). Results. The incidence of unilateral types in the 180 OAs was: type 1-1.11%, type 2-5.56%, type 3-40.56%, type 4-28.33%, type 5-23.33% and type 6, ICA origin of the OA-1.11%. There was found a significant association between the location of the left and right origins of the OAs (Pearson Chi2 = 59.18, p < 0.001), which suggests the presence of a strong symmetry of the origins. Bilateral symmetry of the vertical types of the OA origin was observed in 56.67% of cases; in 43.33% there was bilateral asymmetry. Conclusions. The ICA origin of the OA is an extremely rare variant. For surgical planning or prior to endovascular approaches the topography of the OA origin should be carefully documented, as it may be located from an infrahyoid to a supragonial level.

Multidetector computed tomography (MDCT) angiography in the evaluation of external carotid artery

BACKGROUND

Knowledge about anatomical variants of the external carotid artery is crucial in head and neck surgery and interventional technique. This work aimed to present the frequency of regular and another variant of the external carotid artery using 128 multidetector computed tomography (MDCT) angiography.

MATERIALS AND METHODS

This retrospective study included 120 patients in our university hospital between April 2017 and October 2021. They were 65 men and 55 women (mean age, 45.6 years; range, 18-65 years). They were angiofibroma (10 patients), cerebral stroke (28 patients), partial glossectomy (13 patients), submandibular gland excision (12 patients), parotidectomy (17 patients), mandibulectomy (5 patients), and a thyroidectomy (35 patients). We retrospectively analyzed the level and branches of external carotid arteries on both sides of 120 patients.

RESULTS

According to the level of bifurcation; the external carotid artery originated at the level of the upper border of the thyroid cartilage in 164/240 cases (68.3%), and a higher level was detected in 76/ 240 cases (31.7%). The lower level of origin of the external carotid artery was not detected. The superior thyroid, facial, and lingual arteries originated from separate branches of external carotid arteries in 173/240 cases (72.1%). At the same time, the facial arteries originated with lingual arteries in a common trunk in 67/240 cases (27.9%).

CONCLUSION

MDCT angiography is a valuable noninvasive diagnostic tool for evaluating the external carotid artery and its branches.

The occipital artery: a meta-analysis of its anatomy with clinical correlations

The occipital artery arises as one of the main branches of the external carotid artery. The goal of the present meta-analysis was to provide a detailed analysis of the complete anatomy of the occipital artery using the available data in the literature. The main online medical databases such as PubMed, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar were used to gather all studies on anatomical variations, course, branches, and the close anatomical area of the occipital artery. A total of 65 studies were indicated, evaluated, and included in this meta-analysis. The occipital artery was found to run in the groove with a prevalence of 83.93% (95% confidence intervals: 50.53-100.00%). The occipital artery forming a common trunk with another artery had a prevalence of 13.91% (95% confidence intervals: 9.15-19.47%). The mean maximal diameter of the occipital artery was set to 2.26 mm (standard error = 0.15). The mean maximal diameter of the occipital segment of the occipital artery was found to be 1.24 mm (standard error = 0.15). The mean occipital artery length was set to 131.93 mm (standard error = 3.02). In conclusion, the authors of the present study believe that this is the most accurate and up-to-date meta-analysis regarding the anatomy of the occipital artery. Knowledge about this structure can be of great use when performing revascularization procedures, such as the occipital artery-posterior inferior cerebellar artery bypass, or reconstructive procedures, such as the occipital artery fascial flap.

Morphometry of the Entire Internal Carotid Artery on CT Angiography

Background and Objectives: Knowledge of the internal carotid artery’s (ICA) morphometric features is influential in outlining surgical and minimally invasive procedures in the neurovascular field. Many studies have shown divisive numbers regarding the ICA’s caliber, with the measuring point of the artery sometimes differing. This study presents ICA dimensions based on computed tomography angiography in each of its seven segments as per Bouthillier’s classification, correlating vascular dimensions with anthropometric parameters. Materials and Methods: A thorough CT angiography analysis was performed on 70 patients with internal carotid vessels unaffected by atherosclerotic disease. The extracranial part of the ICA was measured in four locations—carotid bulb, post-bulbar dilation, at its cervical midpoint, and below its entrance into the carotid foramen. Single landmarks were used for measurements in the intracranial segments. ICA length was assessed in the neck region and also in the cranial cavity. Craniometric measurements were performed on sagittal and coronal CT reconstructions. Patient height was taken into consideration. Results: The largest ICA portion is near its origin in the carotid sinus area (7.59 ± 1.00 mm), with a steep decline in caliber following its extracranial course. Distal ICA presented values somewhat similar to its proximal intracranial segment diameters (4.67 ± 0.47 mm). Dimensions of the ICA in the intracranial segments start from a value of 4.53 ± 0.47 mm and decrease by approximately 40% when reaching the origin of the middle cerebral artery (2.71 ± 0.37 mm), showing a marked decrease in caliber after the emergence of the most critical collateral artery, the ophthalmic branch. The length of the ICA varies between genders, with the male ICA being about 10 mm longer in total length than female ICA; this difference is also correlated with patient height and skull dimensions. Conclusions: Both intra- and extracranial ICA have variable dimensions and length related to gender and anthropometric parameters, with no significant differences obtained concerning side or age.

True terminal pentafurcation of the external carotid artery and terminal trifurcation of the contralateral one, occipitoauricular trunk, retropharyngeal internal carotid artery

The external carotid artery (ECA) commonly ascends in the retromandibular fossa and bifurcates posteromedial to the neck of the mandible into the maxillary (MA) and superficial temporal (STA) arteries. In its course in the neck, the ECA gives off the superior thyroid, lingual (LA), facial (FA), ascending pharyngeal (APA), occipital (OA) and posterior auricular (PAA) arteries. When the computed tomography angiograms of a 65-year-old male were evaluated, extremely rare anatomical variations of both ECAs were found. The right ECA trifurcated terminally at the neck of the mandible into the MA, STA and middle meningeal artery (MMA). A right occipitoauricular trunk was found coursing posterior to the ECA to further divide in the parotid region into the OA and PAA. The left ECA had a terminal pentafurcation, with the FA/APA/OA/MA/STA pattern, and the PAA branched from the STA. This pentafurcation occurred deep to the angle of the mandible and the medial pterygoid muscle, in front of the internal jugular vein. The MA ascended behind the medial pterygoid muscle, deep to the posterior border of the ramus of the mandible and reached the lateral pterygoid muscle to continue normally. The right internal carotid artery (ICA) had a lower medial curvature intercalated between the third cervical vertebra and the pharynx. To the authors' knowledge, a terminally pentafurcated ECA has not been previously recorded, and a terminal trifurcation with an added MMA has only been observed once. Such drastically modified arterial patterns expose the branches emerging from the pentafurcation and pose a risk during surgical approaches within the parotid region. Additionally, a retropharyngeal curvature of the ICA could be subject to compression during deglutition.