Topography of carotid bifurcation: considerations for neck examination

Anatomic evaluation of the height of the carotid bifurcation by 4th year medical students using vascular ultrasonography

Background

The carotid bifurcation is known for its anatomical variations, involving structures that can be assessed by ultrasound examination. Knowledge of unusual anatomy is crucial in surgical procedures, directly influencing their outcomes.

Objectives

To assess whether fourth-year medical students with prior training are capable of performing ultrasound examinations to compare the height of the carotid bifurcation between men and women.

Methods

602 carotid bifurcations from 301 participants were identified by ultrasound examinations conducted by medical students after prior training by a professional qualified in vascular ultrasound. After each examination, the results were verified by a specialist physician. Gender, age, and bilateral measurement of the distance between the carotid bifurcation and the ear lobe were compared.

Results

The students' measurements differed from the specialist physician's measurements by more than 0.2 cm in just 8 examinations. On the right side, the average height of the carotid bifurcation relative to the earlobe was 5.9 cm, compared to 5.8 cm on the left side, for the whole sample. The distance on the right side was significantly shorter among the women, with an average of 5.6 cm, compared to 6.3 cm among the men (p<0.0001). The distance on the left side was also significantly shorter in women, with an average of 5.4 cm, compared to 6.2 cm among the men (p<0.0001). The difference between sides was not statistically significant between the sexes.

Conclusions

After training, medical students demonstrate high accuracy in the technique of measuring the carotid bifurcation height using vascular ultrasound. Men showed a tendency for the bifurcations to be located farther from the earlobe compared to women.

Is low carotid bifurcation determined by vertebral level always convenient for surgical approach?

Although high-level carotid bifurcation (HCB) could lead to notable surgical difficulty, the definitive reference point for HCB is unclear. HCB is typically characterized as carotid bifurcation (CB) located higher than the level of the third cervical vertebra (C), however, a major obstacle regarding carotid artery surgical exposure is angle of the mandible (AM). The objective of this study was to investigate CB level, define HCB in relation to AM and vertebral levels, and measure the vertical distance from HCB to ipsilateral AM. Moreover, the percentage of surgically challenged CBs, misclassified as low CBs (LCB) based on vertebral level, was investigated. Patients who underwent neck computed tomography angiography were retrospectively studied. HCBs were classified into two categories: CBs above the C3 and either at or above the ipsilateral AM. Of 172 CBs (86 patients; 57 men, 29 women), CB was mostly found at C3 (44.19%), whereas AM was commonly located at C2 (51.16%). Based on vertebral level and AM, HCBs were detected in 10.47% and 20.35% of CBs, respectively. The association of HCBs determined by either C3 or AM between both sides in each individual was nonsignificant (p>0.05), but HCBs determined by C3 level were predominant in women (OR = 3.58, 95%CI = 1.31-9.80). Considering both C3 and AM, there was 8.72% of HCBs. The remaining 91.28% was classified as LCBs, including 11.63% of CBs located at both C3 and AM which were actually classified as HCBs if determined by AM. In cases of CBs above AM level, the mean vertical distance was as high as 6.56 ±2.41mm.

The Carotid-Hyoid Topography Is Variable

Background and Objectives: The carotid bifurcation (CB) is presented in most anatomy textbooks as having a unique location at the upper margin of the thyroid cartilage. Although a number of case reports have provided evidence of the possibility of carotid artery location either lateral or medial to the greater hyoid horn, these reports have not established specific anatomic possibilities and prevalences. Materials and Methods: We retrospectively analysed a batch of 147 CT angiograms for 12 types of carotid-hyoid relationships and classified the bilateral combination possibilities of these types. Results: In 168/294 sides there were no carotid-hyoid relationships. Type I, external carotid artery (ECA) medial to the greater horn of the hyoid bone (GHHB), was observed in 0.34%; type II, internal carotid artery (ICA) medial to GHHB, in 0.34%; type III, ICA and ECA medial to GHHB, in 1.02%; type IV, common carotid artery (CCA) medial to GHHB, in 1.02%; type V, CB medial to GHHB, in 0.34%; type VI, ECA lateral to GHHB, in 20.41%; type VII, ICA lateral to GHHB, was not recorded; type VIII, ECA and ICA lateral to GHHB, in 3.74%; type IX, CCA lateral to GHHB, in 8.5%; type X, CB lateral to GHHB, in 6.46%; type XI, ECA lateral and ICA medial to GHHB, in 0.34%; and type XII, ICA lateral and ECA medial to GHHB, in 0.34%. Bilateral symmetry was found in 70.74% of cases, including the null types without carotid-hyoid relationships as well as types IV, VI, VIII, IX, and X. There was a highly significant association between the left and right variants of the carotid-hyoid relationship. Conclusions: Mechanical compression of the hyoid bone on the carotid arteries has various undesirable effects on the ICA and cerebral circulation. Underlying these are several variational anatomical patterns of carotid-hyoid relationships, which can be accurately documented on CT angiograms. A case-by-case anatomical study is better than assuming the carotid anatomy learned from textbooks.

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.

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.

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.

Topography of the Anatomical Landmarks of Carotid Bifurcation and Clinical Significance

OBJECTIVE

Carotid bifurcation (CB) and its terminal branches are the most common sites of atherosclerotic plaques. In surgical treatment, these plaques can be reached by an endarterectomy technique. The success of the technique can be achieved with good anatomical knowledge of these arteries and their relationships with surrounding structures.

MATERIALS AND METHODS

The study was performed retrospectively on archived images of patients with computed tomography angiography (CTA). Two hundred forty-seven patients who met the criteria were included in this study. Three-dimensional (3D) reconstructions of two-dimensional CTA images were made automatically using the open-source software Horos v.4.0.0. The distance between the transverse plane passing through the bifurcation point (BP) and the defined planes of the surrounding structures was evaluated.

RESULTS

CB was observed below the mastoid process, gonion point, and hyoid bone. CB was observed above the thyroid cartilage. Carotid bifurcation was seen at 15 levels in total, the lowest in the upper 1/3 of the C6 vertebral body and the highest in the lower 1/3 of the C2 vertebral body. In all cases, the most common level was the C3 lower level.

CONCLUSION

All these values, which emerged as a result of the study, provide general information about the topography of the CB according to the neighboring structures. Estimating the location of the CB according to the gonion and hyoid bone will give a more accurate result. The vertebral level on the right side increased in direct proportion to age; there was no similar relationship on the left side. It is necessary to be aware of these anatomical variations in order to prevent various iatrogenic complications.

Geometric morphometric study of anterior branches of external carotid artery and carotid bifurcation by 3D-CT angiography

PURPOSE

The aim of our study was to determine the variations of the anterior branches of the external carotid artery (ECA) and investigate the morphometric and geometric features of the anterior branches of the ECA and carotid bifurcation (CB).

METHODS

A total of 563 ECAs were included from 288 patients in the study. Classification and exit angles of anterior branches of ECA and determination of vertebral levels of CB and anterior branches were performed.

RESULTS

The anterior branch variants of the ECA were observed in 8 different subgroups. The most common variations were type Ia 42.3% (n = 120) on the right and type Ib 40.9% (n = 114) on the left. When looking at the vertebral levels, CB was detected at C4 level in 32.9% of total ECAs (n = 185), STA was at C4 level in 33.4% of total ECAs (n = 188), LA was at C3 level in 50.1% of total ECAs (n = 282), and FA was at C2 level in 37.3% of total ECAs. The mean CB angle in all cases was 59.93° ± 16.04. In the anterior branches of the ECA in cases belonging to the Type I group, the widest angle belonged to FA (R = 116.88 ± 27.04°, L = 110.32° ± 25.94).

CONCLUSION

In conclusion, a new classification of the variations of the anterior branches of the ECA was made on the basis of the CTA images to gain more practicality in surgical procedures. This study revealed for the first time the angular and level relationship between CB and ECA anterior branches.

Bilateral higher carotid termination with rare anomalous emergence of ventral branches of the external carotid arteries: A cadaver study

The common carotid artery bifurcates into two terminal branches—the external and internal carotid arteries. The head, neck, and face regions principally get their blood supply from the external carotid artery and its branches. Some previous articles have mentioned the abnormal pattern of the external carotid artery branching and its variable origin. In this article, a rare case has been documented, having the combination of anomalies of the high carotid termination and bilateral variable origin of the ventral branches of the external carotid artery encountered during routine dissection of the head and neck region of a 55-year-old male cadaver in the Department of Anatomy. In this instance, on the right side of the neck, we observed the presence of a thyrolinguofacial trunk which arose from the ventral surface of the external carotid artery, and on the left side, the linguofacial trunk emerged from the ventral surface of the external carotid artery while the superior thyroid artery branched off directly from the left common carotid artery. This apart, there was bilateral high termination of the common carotid artery. Although the exact embryogenesis of such common arterial trunks anomalies and high carotid termination is not clear, detailed and precise anatomical knowledge of such a combination of anomalies will provide further insight for better radiological evaluation and to avert iatrogenic vascular injuries during any surgical procedures of the head and face region.

The Carotid Endarterectomy Cadaveric Investigation for Cranial Nerve Injuries: Anatomical Study

Cerebral stroke continues to be one of the leading causes of mortality and long-term morbidity; therefore, carotid endarterectomy (CEA) remains to be a popular treatment for both symptomatic and asymptomatic patients with carotid stenosis. Cranial nerve injuries remain one of the major contributor to the postoperative morbidities. Anatomical dissections were carried out on 44 sides of 22 cadaveric heads following the classical CEA procedure to investigate the variations of the local anatomy as a contributing factor to cranial nerve injuries. Concurrence of two variations was found to be important in hypoglossal nerve injury: the presence of a direct smaller vein in proximity of the carotid bifurcation, and the intersection of the hypoglossal nerve (HN) with this vein. Based on the sample investigated, this variation was observed significantly higher on the right side. Awareness of possible anatomical variations and early ligation of any small veins can significantly decrease iatrogenic injury risk.

Anterior cervical discectomy and fusion in the setting of kissing carotids: A technical report and literature review

BACKGROUND

The "kissing carotids" (KCS) phenomenon refers to bilateral retropharyngeal displacement of the internal carotid arteries (ICA). This anomalous anatomy can impose a significant surgical challenge to spine surgeons.

OBJECTIVE

In this report, we describe our approach for an anterior cervical discectomy and fusion in the setting of kissing carotids.

METHODS

We discuss our case, surgical technique, rationale, and outcome. Additionally, we conducted a systematic review of the literature.

CASE DESCRIPTION

An 82-year-old female presented to our service with progressive myelopathy. Cervical spinal imaging revealed a large disc herniation at C3-C4 and severe spinal canal stenosis. Vascular imaging showed anomalous ICAs bilaterally overlying the prevertebral fascia at the midline. The patient received aspirin preoperatively and underwent a multidisciplinary approach with neurosurgery and otolaryngology. A standard transcervical approach centered on the C5-C6 disc space, where the carotid arteries splayed most from midline, allowed for facilitated visualization and mobilization of the vessels. Prevertebral dissection was then performed rostrally to the C3-C4 disc space. The patient was put into burst suppression prior to retraction and underwent uncomplicated anterior discectomy and fusion.

CONCLUSIONS

KCS is a rare but critical presentation of extreme medial displacement of bilateral ICAs. Few cases have been reported in the spinal surgery literature. Knowledge of this rare variant is important to avoid iatrogenic injury and complications.

Preoperative Localization of the Carotid Bifurcation for Cervical Carotid Exposure Using the Mastoid-Hyoid Line

Background and Importance:

The location of the carotid bifurcation (CB) is highly variable, which makes precise exposure of the cervical carotid artery difficult, especially in transverse incisions. The method for preoperative localization of the CB is not well established. We used the distance from the mastoid-hyoid (M-H) line to the CB, measured preoperatively with computed tomography angiography, to localize the location of the transverse skin incision. We describe and evaluate the accuracy of a method for preoperative localization of the CB for cervical carotid exposure.

Methods:

The researchers retrospectively evaluated 16 patients with aneurysms arising from the internal carotid artery (ICA) who had received cervical carotid exposure using the localization method of incision and were retrospectively evaluated from February 2018 to November 2019. The method of measurement and localization of the skin incision are described, and two illustrative cases are demonstrated.

Results:

Saccular aneurysms of the ophthalmic (C2) segment and communicating (C1) segment of the ICA were found in 8 and 8 patients, respectively. Nine patients had left-sided exposure, and 7 patients had right-sided exposure. The mean distance from the M-H line to the CB was 2.1 cm (range 0.5–3.5 cm). The accuracy of this method was 93.8%. No paralysis of the depressor anguli oris or the depressor labii inferioris was found postoperatively.

Conclusion:

The distance from the M-H line to the CB can be used to estimate transverse skin incisions for cervical carotid exposure.

Origin variations of the superior thyroid, lingual, and facial arteries: a computed tomography angiography study

PURPOSE

To determine the anatomical variations and morphology of the external carotid artery (ECA) and its anterior branches.

METHODS

Using computed tomography angiography (CTA), the origin, internal diameter, and surface laterality emergence of the superior thyroid (STA), lingual (LA), and facial (FA) arteries were evaluated retrospectively evaluated and classified. The bifurcation level of the common carotid artery (CCA) in relation to the cervical vertebrae and disc was also determined.

RESULTS

A total of 76 CTA were included in the study. STA originated from the carotid bifurcation (CB) (type I), CCA (type II) and ECA (type III) in 20.4 (31/152), 17.1 (26/152) and 50.7% (77/152) cases, respectively. Also 10.5% (16/152) arose from a shared trunk with LA as a thyrolingual trunk (TLT) (type IVa), and absent in 1.3% (2/152). LA originated in the CB in only one case. A linguofacial trunk (LFT) was present in 14.5% (22/152). Mean diameters of STA, LA and FA were 1.70, 1.95 and 2.45 mm, respectively. Meanwhile, surface laterality were predominately from anteromedial, medial, and anterior, respectively. CB was mainly on C3 or C3-C4 (55.9% of cases).

CONCLUSIONS

STA origin below the ECA is a common finding. Our population presented the highest percentage of TLT (10.5%) and high CB (9.8%) in literature. Considering these variations are important to prevent complications in neck surgical procedures.

A New Method for Determining the Level of the Carotid Artery Bifurcation

Exact localization of the bifurcation of the common carotid artery using skin surface landmarks is important for various diagnostic and therapeutic purposes, including emergency cases. Traditional methods have confirmed their accuracy in only a certain percentage of cases and there are inconsistencies among various publications. The cervical computed tomography-angiographic examinations for any diagnostic purpose between June 2017 and December, 2017 in the authors' hospital were examined. Measurements were performed for (MT-CB) and (MT-SE) distances and the results were recorded [MT = The tip of the mastoid process; CB = common carotid artery bifurcation; SE = sternal extremity of the clavicle]. Cervical computed tomography angiography was found in the records of 91 patients in the 6-month period between June 2017 and December 2017. After exclusion criteria were applied, a total of 116 carotid bifurcation levels on the right and left sides were measured in 58 patients. The mean MT-CB distance was 6.29 ± 0.9 cm (range: 2.9-8.4 cm). The mean distance between MT and SE was 15.3 ± 1.7 cm (range: 9.9-19.0 cm). The (MT-CB): (MT-SE) ratios ranged from 29% to 51% with a mean of 41 ± 4.2% (95% CI: 39.88%-42.10%) and a median of 41.1% (P < 0.05) (Kolmogorov-Smirnov test). The distance ratio values did not change significantly according to age and gender (respectively P = 0.341, P = 0.093). These results show that the CB is usually located at two-fifths of the distance from the mastoid tip to the sternal extremity of the clavicle and closer to the mastoid tip.

Do Asians have Higher Carotid Bifurcation? A Computed Tomographic Angiogram Study of the Common Carotid Artery Bifurcation and External Carotid Artery Branching Patterns

Introduction:

Carotid endarterectomy is a major treatment modality for high-grade carotid stenosis. Preoperative identification of the level of the carotid bifurcation and its branching pattern is important in planning for adequate exposure and cross-clamping to achieve hemostasis during the procedure. Most of the previous studies on carotid arteries were performed in cadavers.

Methods:

We studied levels of carotid bifurcation compared relatively with the level of the vertebral body and ipsilateral angle of the mandible and its branching pattern using computed tomographic angiogram (CTA) carotid with multiplanar reconstruction and three-dimensional imaging in 100 CTA studies.

Results:

Most of the carotid bifurcations were located at the level of C3–C4 vertebral body and 12% were considered to be high bifurcation. Carotid bifurcations were located below the angle of the mandible in 83.5%. The superior thyroid, facial, and lingual arteries arose from separate branches of external carotid arteries in 67.7% of samples. Facial arteries arose in common trunk with lingual arteries in 29.2%, much more common than previous cadaveric studies. The lingual arteries arose with superior thyroid arteries in 2%, while occipital arteries had high variations in their branching patterns.

Conclusions:

CTA is an effective and reliable modality for preoperative evaluation of the carotid system in patients undergoing carotid endarterectomy and other carotid procedures. Higher percentage of high carotid bifurcation was found in our study, concordant with other Asian cadaveric studies. We assumed that carotid bifurcation of Asian tends to be located slightly higher than those of the Caucasian population.

Proximity of the Carotid Bifurcation to the Laryngeal Prominence: Results of a Cadaver Study and Recommendations for Safe Pulse Palpation

BACKGROUND/PURPOSE

The carotid bifurcation (CB) is the location of the carotid sinus and the baroreceptors and is also a major site for atherosclerotic plaque formation. Health care providers have therefore been cautioned to avoid the CB during carotid pulse palpation (CPP) to prevent triggering the baroreflex, occluding an artery, or propagating a thrombus. Potential risks of adverse events during CPP may be greater for older adults due to age-related vascular changes and increased risk of baroreceptor hypersensitivity. The exact location of the CB relative to easily identifiable landmarks has, however, not been well-studied. The purpose of this descriptive study was to identify the location of the CB relative to key landmarks in a cadaver sample and to make recommendations allowing clinicians to avoid the CB during CPP.

METHODS

The CB and other regional landmarks in 17 male and 20 female cadavers were exposed by dissection and pins were placed at all landmarks. Digital calipers were then used to measure the distance between the CB and all landmarks.

RESULTS AND DISCUSSION

The mean vertical distance from the laryngeal prominence (LP) to the CB was 25.14 mm for females and 36.13 mm for males. No CBs were located below the LP. Ninety-four percent of female CBs and 100% of male CBs were located above the LP, and 74% of female subjects and 87% of male subjects had CBs greater than 20.00 mm superior to the LP. No clinically relevant relationships were found between the CB and any of the other measured landmarks.

CONCLUSIONS

Based on this cadaver sample, CPP below the level of the LP in a supine individual would be unlikely to compress the CB and thus unlikely to trigger the baroreflex or occlude the region of greatest atherosclerotic buildup. If a pulse is not palpable below the LP, moving vertically up to 1 cm above the LP in a supine individual would be likely to compress the CB in only a small number of cases.

Ultrasonographic Criteria to Define the Lower Limits of Neck Node Levels 2 and 3

OBJECTIVE

To find ultrasonographic landmarks to define the lower limits of neck node levels 2 and 3.

METHODS

Data were collected prospectively between February 2014 and January 2015. In total, 103 patients were recruited (50 men and 53 women), and the mean age was 50.9 years (range: 18-89). At the lower level of the hyoid, we classified ultrasonographic findings as hyoid type (HT)1 when the internal and external carotid arteries were visualized separately, HT2 when the internal and external carotid arteries joined together, and HT3 when the common carotid artery was visualized. At the lower border of the cricoid cartilage, we classified ultrasonographic findings as cricoid type (CT)1 when the omohyoid reached the medial half of the common carotid artery, CT2 when the omohyoid reached the lateral half of the common carotid artery, CT3 when the omohyoid reached the medial half of the internal jugular vein, and CT4 when the omohyoid reached the lateral half of the internal jugular vein.

RESULTS

At the lower border of the hyoid, HT1 was most commonly observed in 59.2%, whereas HT2 and HT3 were observed in 31.3% and 9.7%, respectively. At the lower border of the cricoid cartilage, CT3 was most commonly observed in 52.9%, whereas CT2, CT4, and CT1 were observed in 20.4%, 14.1%, and 12.6%, respectively.

CONCLUSION

HT1 and CT3 can be suggested ultrasonographic landmarks for the lower limits of levels 2 and 3, respectively.

LEVEL OF EVIDENCE

2. Laryngoscope, 129:2487-2490, 2019.

Common left carotid bifurcation at C7-Th1 level: a rare anatomical variant

The left common carotid artery usually bifurcates to the internal and external carotids at or near the superior border of thyroid cartilage. In head and neck surgery, the common carotid arteries are important landmarks, defining the plane of dissection during radical neck surgeries. According to the literature, many variations exist regarding the carotid bifurcation. Anatomical knowledge of these variants is important for surgical approaches in the head and neck regions, to avoid devastating complications that may occur, mainly during anterior neck dissections. We report an interesting case of a 75-year-old male patient with low bifurcation of the left common carotid artery, accidentally found during a routine carotid Doppler ultrasonography. Bifurcation was located at the C7-Th1 intervertebral disc height, approximately 4 cm from the aortic arch.

Predictors of antegrade flow at internal carotid artery during carotid artery stenting with proximal protection

BACKGROUND

Carotid artery stenting (CAS) with proximal occlusion effectively prevent distal cerebral embolism by flow arrest at internal carotid artery (ICA); however, the method can expose antegrade flow at ICA due to incomplete flow arrest. The aim of this study was to identify predictors of antegrade flow during CAS with proximal protection.

METHODS

We retrospectively analyzed clinical and angiographic data among 143 lesions treated with CAS with proximal protection by occluding the common carotid artery (CCA) and external carotid artery (ECA). Flow arrest or antegrade flow at ICA was confirmed by contrast injection during proximal protection.

RESULTS

Antegrade flow at ICA was observed in 12 lesions (8.4%). Compared with lesions in which flow arrest of ICA was achieved, the diameter of the superior thyroid artery (STA) was significantly larger (2.4 ± 0.34 vs. 1.4 ± 0.68 mm, p < 0.001), and the rate of ECA branches other than the STA located 0-10 mm above the bifurcation was significantly higher (50 vs. 8.4%, p < 0.001). Results of multivariate analysis revealed that a diameter of the STA ≥ 2.3 mm (OR 44, 95% CI 8.1-237; p < 0.001) and ECA branches other than the STA located 0-10 mm above the bifurcation (OR 6.0, 95% CI 1.1-32; p = 0.036) were independent predictors of antegrade flow.

CONCLUSIONS

Distal filter protection should be combined with proximal protection for the lesions with antegrade flow to prevent distal migration of the carotid debris.

The accuracy of anatomical landmarks for locating the carotid sinus

BACKGROUND

carotid sinus massage (CSM) is a valuable clinical test for carotid sinus syndrome (CSS) and relies on accurately locating the carotid sinus (CS).

OBJECTIVE

in this study, we sought to examine the accuracy of using anatomical landmarks for locating the CS.

METHODS

consecutive patients (n = 20) were recruited prospectively. Two clinicians, trained in CSM, were asked to locate the CS using anatomical landmarks. A point on the skin overlying the CS was then marked by a vascular technician using ultrasound. Accuracy of techniques was compared using intra-class correlation coefficients and Bland-Altman statistics.

RESULTS

anatomical landmarks underestimated the CS location by 1.5 ± 1.3 cm. Error extremes ranged from 4 cm below to 2 cm above CS using anatomical landmarks. A moderate correlation between ultrasound and anatomical landmarks was found, r = 0.371 (P = 0.031).

CONCLUSION

this is the first study to characterise the accuracy of standard anatomical landmarks used in CSM. Results suggest that the point of maximal pulsation has the lowest associated error. Future work should examine CSM yield across this and a range of other methodological factors.

Anatomical Considerations on Surgical Anatomy of the Carotid Bifurcation

Surgical anatomy of carotid bifurcation is of unique importance for numerous medical specialties. Despite extensive research, many aspects such as precise height of carotid bifurcation, micrometric values of carotid arteries and their branches as their diameter, length, and degree of tortuosity, and variations of proximal external carotid artery branches are undetermined. Furthermore carotid bifurcation is involved in many pathologic processes, atheromatous disease being the commonest. Carotid atheromatous disease is a major predisposing factor for disabling and possibly fatal strokes with geometry of carotid bifurcation playing an important role in its natural history. Consequently detailed knowledge of various anatomic parameters is of paramount importance not only for understanding of the disease but also for design of surgical treatment, especially selection between carotid endarterectomy and carotid stenting. Carotid bifurcation paragangliomas constitute unique tumors with diagnostic accuracy, treatment design, and success of operative intervention dependent on precise knowledge of anatomy. Considering those, it becomes clear that selection and application of proper surgical therapy should consider anatomical details. Further research might ameliorate available treatment options or even lead to innovative ones.

Anomalous External Carotid Artery-Internal Carotid Artery Anastomosis in Two Patients with Proximal Internal Carotid Arterial Remnants

Two angiographic instances of anomalous external carotid artery (ECA) and internal carotid artery (ICA) anastomosis are described, each occurring at the C2-3 level and bearing remnants of proximal ICA. The ICA remnant of one patient (identifiable immediately upon bifurcation of the common carotid artery) was hypoplastic, and that of the other patient was an occluded arterial stump. These features are not typical of non-bifurcating ICA. The occipital artery originated from an anomalous connection in one instance and from the main trunk of the ECA (just past the ECA-ICA connection) in the other.

Mechanism of loss of consciousness during vascular neck restraint

Vascular neck restraint (VNR) is a technique that police officers may employ to control combative individuals. As the mechanism of unconsciousness is not completely understood, we tested the hypothesis that VNR simply compresses the carotid arteries, thereby decreasing middle cerebral artery blood flow. Twenty-four healthy police officers (age 35 ± 4 yr) were studied. Heart rate (HR), arterial pressure, rate of change of pressure (dP/d t), and stroke volume (SV) were measured using infrared finger photoplethysmography. Bilateral mean middle cerebral artery flow velocity (MCAVmean) was measured by using transcranial Doppler ultrasound. Neck pressure was measured using flat, fluid-filled balloon transducers positioned over both carotid bifurcations. To detect ocular fixation, subjects were asked to focus on a pen that was moved from side to side. VNR was released 1–2 s after ocular fixation. Ocular fixation occurred in 16 subjects [time 9.5 ± 0.4 (SE) s]. Pressures over the right (R) and left (L) carotid arteries were 257 ± 22 and 146 ± 18 mmHg, respectively. VNR decreased MCAVmean (R 45 ± 3 to 8 ± 4 cm/s; L 53 ± 2 to 10 ± 3 cm/s) and SV (92 ± 4 to 75 ± 4 ml; P < 0.001). Mean arterial pressure (MAP), dP/d t, and HR did not change significantly. We conclude that the most important mechanism in loss of consciousness was decreased cerebral blood flow caused by carotid artery compression. The small decrease in CO (9.6 to 7.5 l/min) observed would not seem to be important as there was no change in MAP. In addition, with no significant change in HR, ventricular contractility, or MAP, the carotid sinus baroreceptor reflex appears to contribute little to the response to VNR.

Computed tomography and magnetic resonance angiography in the evaluation of aberrant origin of the external carotid artery branches

Aim of our study was to evaluate the prevalence of aberrant origin of the branches of the external carotid artery (ECA) in 97 patients by computed tomography (CTA) and magnetic resonance angiography (MRA) and to compare the accuracy of these two techniques in the visualization of the ECA system. All patients underwent CTA and MRA examination of the head and neck. Multiplanar and volumetric reformations were obtained in all cases. For each set of images, the presence of aberrant origin of the branches of the external carotid artery was investigated. MRA and CTA images of each patient were compared to define their information content. Anatomical anomalies were found in 88 heminecks, with a prevalence of 53.3%. In the 61 patients in whom the CTA was performed before the MRA, the latter method showed only 92% of abnormalities detected at the first examination; in the 36 patients in whom MRA was performed first, CTA identified all of the anomalies highlighted by the former, adding 12 new. Knowledge of the anomalies of origin of the ECA branches is essential for the head and neck surgeon; the high prevalence of anomalies found in our series as in the previous studies indicates the opportunity to perform a CTA or a MRA of the head and neck before any surgical or interventional procedure. CTA is the method of choice in the evaluation of anomalies of origin of the branches of the ECA and in the definition of their course.

Superior thyroid artery origin in Caucasian Greeks: A new classification proposal and review of the literature

Studies on the origin of the superior thyroid artery, define that it could originate either from the external carotid artery, (at the level of common carotid bifurcation), or from the common carotid artery. However, there is a classical anatomic knowledge that the superior thyroid artery is a branch of the external carotid artery. Variability in the anatomy of the superior thyroid artery was studied on 100 carotids. Moreover, a review about the origin of superior thyroid artery between recent and previous cadaveric, autopsy, and angiographic studies, on adults and fetuses, was carried out. The superior thyroid artery originated from the external carotid artery in 39% and at the level of carotid bifurcation and common carotid artery in 61% of cases. The anterior branches of the external carotid artery were separate in 76% of cases, while common trunks between the arteries were found in 24% of the specimens. A new classification proposal on the origin of the superior thyroid artery is also suggested. In this study, the origin of superior thyroid artery is considered at the level of the carotid bifurcation and not from the external carotid artery as stated in many classical anatomy textbooks. This has a great impact on the terminology when referring to the anterior branches of the external carotid artery, which could be termed as anterior branches of the cervical carotid artery. Head and neck surgeons must be familiar with anatomical variations of the superior thyroid artery in order to achieve a better surgical outcome.