Anatomical Considerations on Surgical Anatomy of the Carotid Bifurcation

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.

Anatomical Variations and Morphometry of Carotid Sinus: A Computed Tomography Study

BACKGROUND

The radiological evaluation of the carotid sinus (CS) anatomy and its morphometry is essentially important for various surgical procedures involving the carotid bifurcation and the CS itself. Despite its tremendous clinical significance, studies dealing with the CS anatomy are seldom reported. Hence, the present study aimed to evaluate the frequencies of the CS positional variants and their morphometry and correlate them with age and body mass index (BMI).

METHODS

In this retrospective cross-sectional study, a total of 754 disease-free carotid arteries were examined using computed tomography angiography scans to determine the CS positional variations (such as types I to III) and its morphometry, including the CS diameter and length. Additionally, the association between these parameters and factors such as sex, age, and body mass index were explored using appropriate statistical tests. The inter-rater agreement of the collected dataset was evaluated using Cohen's Kappa.

RESULTS

The CS type I was observed in 87.67% of the cases, and type II and type III were observed at lower frequencies with 9.02% and 3.32%, respectively. There were statistically significant (p < 0.001) differences observed in the mean diameter and length of the sinus between the sex and the type I CS variations. However, there was no significant and strong correlation between the age and BMI factors with sinus length and sinus diameter. The kappa values for inter-rater agreement ranged from 0.77 to 0.99 for all parameters.

CONCLUSIONS

In type I, the CS length and carotid vessel's diameter is significantly different between the sexes. However, age and BMI do not affect the CS anatomy in radiologically disease-free carotid arteries. Knowledge of the CS variant anatomy is clinically significant as it influences the patients' surgical and physiological outcomes.

The vertical topography of the carotid bifurcation - original study and review

PURPOSE

The vertical level of carotid bifurcation (CB) is commonly indicated at the superior margin of the thyroid cartilage. Few studies observed the CB vertical topography. It was aimed at studying the vertical location of the CB as referred to vertebral and anterior cervical landmarks.

METHODS

An archived lot of 147 computed tomography angiograms was documented for the vertical level of CB referred to vertebral and anterior cervical landmarks. The topography of the CB in relation to anterior landmarks was classified into seven types: (1) at the superior margin of the thyroid cartilage; (2) between the hyoid and the thyroid cartilage; (3) at the hyoid level; (4) between the hyoid and mandible; (5) subgonial or supragonial CB; (6) lower cervical level; (7) intrathoracic.

RESULTS

The most common locations of CB were at C3 (27.21%), C3/C4 (26.19%) and C4 (25.51%). Bilateral symmetry of CB was found in 51.7%, except for C2 and C5/C6. Type 7 was not found, type 3 occurred in 39.12%, type 2 in 24.49%, type 1 in 13.95%, type 4 in 13.61%, type 5 in 6.12%, and type 6 in 2.72% (294 CBs). Bilateral symmetry of anterior types was found in 59.86%. Statistically significant correlations were found between sex and both left and right types and vertebral levels of CB.

CONCLUSIONS

The vertical topography of the CB is highly variable and has sex-related specificity. This detail should be included in the teaching of anatomy. Surgeons and interventionists should better document the carotid anatomy on a case-by-case basis.

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.

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.

Quantitative Prediction of the Location of Carotid Bifurcation and Neurovascular Structures in the Carotid Region: A Cross-Sectional Cadaveric Study

Introduction

The carotid region is encountered in vascular and neurological surgery and carries a potential for vascular and cranial nerve trauma. The carotid bifurcation is an especially important landmark and difficult to predict based on currently established landmarks. This study is a detailed analysis of the carotid region and proposes a novel methodology to predict the height of the bifurcation.

Materials and Methods

Superficial and deep dissections were performed on the anterior triangle of the neck to expose the carotid region in twenty-one formalin-fixed donor cadavers. Musculoskeletal and neurovascular structures were assessed in relation to the carotid bifurcation and the medial border of the clavicle (MBC).

Results

The carotid bifurcation occurred, on average, 11.4 mm higher on the left (p < 0.001; 95% CI: 9.28, 13.54). The superior thyroid artery (p < 0.001), facial vein (p < 0.001), and cranial nerve XII (p < 0.001) were all more distal on the left side when measured from the MBC while the angle of the mandible and stylohyoid muscle remained symmetric. Left- and right-sided vascular structures were symmetric when measured from the carotid bifurcation.

Conclusions

Neurovascular structures within the carotid region are likely to be anatomically superior on the left side while vessels are likely to remain symmetric in relation to the carotid bifurcation. When measured from the MBC, the bifurcation height can be predicted by multiplying the distance between the MBC and mastoid process by 0.65 (right side) or 0.74 (left side). This novel methodological estimation may be easily learned and directly implemented in clinical practice.

Review of the external carotid plexus: anatomy, function, and clinical manifestations

The external carotid plexus is a combination of postganglionic sympathetic fibers derived from the superior cervical ganglion. This plexus travels along the external carotid artery and continues onto the artery’s branches. The external carotid plexus plays an important role in innervating the mid and lower face. Therefore, implications to the plexus may result in facial abnormalities. Herein, we review the anatomy, function, and review its clinical applications.

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.

An Alternative Approach to Carotid Endarterectomy in the High Carotid Bifurcation

BACKGROUND

Surgical exposure of a high carotid bifurcation (HCB) for carotid endarterectomy (CEA) can be technically challenging due to the presence of bony structures in the most cranial portion of the neck and is associated with significant morbidity making carotid artery stenting (CAS) a common alternative. However, a high transverse neck incision with subplatysmal flaps facilitates CEA in these patients without additional exposure techniques. We present a high transverse neck incision with subplatysmal flaps as an alternative to the standard surgical exposure of the carotid bifurcation to facilitate CEA in patients with HCB.

METHODS

Four patients with carotid bifurcations located cranial to the C3-4 vertebral interspace (identified on preoperative imaging) requiring intervention underwent CEA using a high transverse neck incision through an existing skin crease with subplatysmal flap elevation. CEA was performed in a standard fashion with bovine pericardial patch.

RESULTS

Two male and 2 female patients with an average age of 65 years successfully underwent CEA using this incision. One patient underwent concurrent carotid body tumor excision. None of the patients required mandibulotomy or hyoid bone resection. Two patients required division of the posterior belly of the digastric muscle. There were no perioperative complications. Primary patency was 100% in the 4 patients with surveillance studies, and mean follow-up of 160 days (range 54-369 days). There were no significant cranial nerve injuries. No patient required conversion to an endovascular procedure due to inaccessibility of the lesion or subsequent interventions for incomplete endarterectomy.

CONCLUSIONS

A high transverse incision with subplatysmal flaps is a safe, effective, and cosmetically preferable surgical approach in patients with HCB requiring carotid artery intervention and may be an alternative to CAS.

Prevention of Back Bleeding During Carotid Endarterectomy: Analysis of Clamping Techniques

OBJECTIVE

Complete control of back bleeding during carotid endarterectomy (CEA) is important. We investigated the causes of back bleeding during CEA and techniques for the control of bleeding.

METHODS

A retrospective review was performed of 214 CEA procedures. We assessed the results of routine preoperative examinations, instruments used for arterial clamping (vessel loop and crude or bulldog clamps), and severity of carotid artery stenosis and arterial wall calcification. The study end point was incomplete control of back bleeding before arteriotomy. Factors associated with back bleeding were identified by univariate analysis. The culprit artery and intraoperative technique used in patients with back bleeding were also determined.

RESULTS

Transient back bleeding occurred in 19 CEA procedures (8.9%). Back bleeding was from the ascending pharyngeal artery in 9 cases, common carotid artery in 8 cases, and external carotid artery in 2 cases. Univariate analysis identified the following factors as being related to incomplete control of back bleeding: moderate carotid artery stenosis (20 mm thick) and use of bulldog clamps.

CONCLUSIONS

Transient back bleeding during CEA was uncommon, with the risk factors being severe carotid calcification and moderate carotid stenosis. Transient back bleeding was managed by clamping an undetected ascending pharyngeal artery or by additional clamping of the common carotid or external carotid artery. The vessel loop and crude were superior to the bulldog clamp for clamping the carotid artery.

A cadaveric study on variations in branching pattern of external carotid artery

Variations in the vascular anatomy of the carotid triangle have been reported in current scientific literature. The carotid arteries, being the major feeding arteries of the head and neck deserve special importance and protection from iatrogenic injury during radiological evaluations and surgical interventions. The present study was carried out over a period of 4 years from 2012–2016 to assess the variant anatomy of external carotid artery. The external carotid artery and its branches were dissected bilaterally in 40 formalin embalmed cadavers. The external carotid artery was traced from its origin to termination and variations in the branching pattern as well as the level of the carotid bifurcation were observed and analysed. A higher carotid bifurcation was observed in 25% cases. The linguofacial trunk was the commonest variation noted in the branching pattern seen in 20% cases. A single case of unilateral thyrolinguofacial trunk was also observed. The external carotid artery gave rise to accessory branches in 7.5% cases namely the superior laryngeal, accessory ascending pharyngeal and masseteric branches. A slender branch to the internal jugular vein was also observed in one case. These findings may provide further insight into the understanding of the vascular anatomy of the carotid triangle to the curious student, the discerning radiologist and the vigilant surgeon to avert complications and help improve overall treatment outcome.

An Anatomical Variation in the Cervical Carotid Artery of a Young Stroke Patient

The cervical carotid artery has been reported to show anatomical variations. We report the case of a young stroke patient with a small right-parietal-lobe infarction whose cervical carotid artery showed anatomical variation. The right internal carotid artery (ICA) originated at the C2 level of the external carotid artery with protrusion at the right carotid bifurcation. The vessel wall of the protrusion showed a high signal intensity on T1-weighted magnetic resonance carotid plaque imaging. The protrusion, considered a remnant of the ICA, possibly caused the stroke due to the formation of thrombi as a result of changes in blood flow and viscosity.

Carotid Endarterectomy with Autoarterial Remodeling of Bifurcation of the Common Carotid Artery and Carotid Endarterectomy with Patch Closure: Comparison of Methods

BACKGROUND

The objectives of our research were to identify whether the new method of carotid endarterectomy (CEA) with autoarterial remodeling of bifurcation of the common carotid artery (ARBCCA) influences daily parameters of blood pressure and heart rate (HR) while monitoring them on a daily basis and to assess the efficacy of the suggested method.

MATERIALS AND METHODS

It is a prospective randomized comparative study. The first group (n = 100) included patients that underwent ARBCCA, the second group (n = 100) included patients that underwent "classic" CEA with xenopericardial patch closure. Diurnal Holter recording of blood pressure and (HR) was performed before and after the surgical treatment in both groups.

RESULTS

Surgical treatment in both groups leads to an increase of HR, arterial hypertension time index by systolic blood pressure, and arterial hypertension time index by diastolic arterial blood pressure. The damage of carotid artery bulb increases sympathetic innervation and causes dysregulation of the baroreceptor mechanism.

CONCLUSIONS

In our study, we did not reveal a significant difference in the incidence of postoperative hypertension and the dependence of HR on the choice of surgical technique. Thus, the proposed ARBCCA method does not lead to an increased risk of pre-existing arterial hypertension development. A significant difference is found out on the parameter of the clamping time of carotid arteries in favor to ARBCCA group. Another advantage of the suggested technique is the number of restenosis greater than 50% during the 2-year follow-up (4 [4%] cases (ARBCCA group) versus 12 [12%] cases ["classic" CEA], respectively, P = .037).

CT cervico-cerebral angiography in acute stroke. Can we justify aortic arch imaging?

OBJECTIVES

Computed tomography cervico-cerebral angiography (CTCCA) plays a pivotal role in the evaluation of acute stroke. Currently no evidence justifies the inclusion of the upper chest in the CTCCA field of view. The aim of this study was to assess the prevalence and clinical significance of vascular findings identified on CTCCA in the head, neck, and upper chest regions in patients presenting with acute stroke symptoms.

METHODS

A retrospective review of radiology images and reports of 900 consecutive patients (425 men, 475 women; mean age 63.2 years, age range 19-99 years) with a suspected acute stroke who underwent CTCCA in the emergency department between January 2011 and July 2016. Clinically significant vascular CTCCA findings were recorded for each patient within the head, neck, and upper chest regions, respectively.

RESULTS

Of the 900 patients, clinically significant vascular CTCCA findings were identified in 404/900 (44.8%) patients. 218/900 (24.2%) were located within the head region; 174/900 (19.3%) within the neck; and 12/900 (2.4%) in the upper chest. Of the 12 vascular findings located within the upper chest, 3/900 (0.33%) were related to a clinically significant posterior circulation infarct.

CONCLUSIONS

Routine inclusion of the upper chest on CTCCA is currently difficult to justify in the evaluation of a suspected acute anterior circulation stroke, contributing significantly to total radiation dose without demonstrating significant extra-cranial vascular findings. Prospective studies adopting narrower fields of view excluding the upper chest are necessary.

Revascularization for failed carotid artery stenting in a patient with a rare vertebral artery anomaly

There is a growing cohort of patients requiring complex revascularization for failed carotid artery stenting. This revascularization can be complex in patients with coexisting supra-aortic vascular anomalies. Aberrant origin of the vertebral artery (VA) is an example of such an anomaly. Although VA anomalies are rare, their occurrence is of significant importance in endovascular and open vascular procedures. We report a case of a 78-year-old man with rare VA anomaly, whose left internal carotid artery ostium was inadvertently covered during a carotid artery stenting procedure. We discuss the carotid artery revascularization in this patient as well as the relevant literature.

A rare diaphragm in the common carotid artery: A first case report and literature review

RATIONALE

We present a case of common carotid artery (CCA) diaphragm. To our knowledge, this is the first reported case in the imaging literature.

PATIENT CONCERNS

A 33-year-old woman presented herself to an annual health examination without any report of ill health.

DIAGNOSES

A stenosis with aneurysm dilation on the proximal part of the right CCA was revealed on ultrasound and CTA, by which a diaphragm-like structure on the stenosis lesion was clearly identified. An anatomic variant of artery was first considered.

INTERVENTIONS

The patient was followed up closely.

OUTCOMES

There was no progression of her CCA stonosis 1 year later.

LESSONS

This unusual and previously unreported case is presented to alert vascular sonographers and radiologists to its existence.