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

A nonbifurcating cervical carotid artery with a remnant of the proximal internal carotid artery that mimicked an aneurysm on magnetic resonance angiography

PURPOSE

To describe a case of a nonbifurcating cervical carotid artery with remnant of the proximal internal carotid artery (ICA).

METHODS

A 47-year-old man with unruptured cerebral aneurysm underwent magnetic resonance (MR) angiography of the neck region and intracranial region. The MR machine was a 3-T scanner. Catheter angiography was performed for the treatment of the aneurysm by coil embolization.

RESULTS

The proximal main trunk of the left external carotid artery (ECA) was absent, and branches arose separately, indicative of a nonbifurcating cervical carotid artery. At the level of the ICA origin, aneurysmal protrusion was found on MR angiography. On catheter angiography, this protrusion was not an aneurysm but a remnant of the proximal ICA.

CONCLUSION

The configuration of the nonbifurcating cervical carotid artery lacks the proximal ECA; however, segmental agenesis of the proximal ICA forms this rare cervical arterial variation. The present case had remnants of the proximal ICA. We speculate that the ICA channel, except for the origin, was occluded after the development of EC-ICA anastomosis, and a nonbifurcating cervical carotid artery with a remnant of the ICA may have formed. Including our patient, only four cases have been reported in the relevant English-language literature.

Anomalous Cervical External Carotid Artery-Internal Carotid Artery Anastomosis Diagnosed Using Digital Subtraction Angiography: A Case Report

Anomalous external carotid artery (ECA)-internal carotid artery (ICA) anastomosis is a rare variant of cervical carotid artery formation that forms an arterial ring in the cervical segment, and its embryological mechanism is still unknown. We report a case of a 41-year-old woman who was incidentally diagnosed with this arterial variation using digital subtraction angiography. The angiography revealed the occipital artery arising from the anastomotic vessel and the ascending pharyngeal artery arising from the ICA near the anastomosis. The proximal ICA was smaller in diameter than the proximal ECA, but it was not stenotic and had sufficient caliber for the distal blood flow. It is commonly believed that the persistence of primitive vessels is the result of agenesis or hypoplasia of the proximal artery. In our case, the anomalous vessel was considered to be the remnant of a primitive anastomosis between the ECA and the ICA via the pharyngo-occipital system, and the narrowing of the proximal ICA may be the result of the remaining ECA-ICA anastomosis.

Congenital external carotid-internal carotid artery anastomosis: a report of three cases and literature review

PURPOSE

Congenital external carotid-internal carotid artery (EC-ICA) anastomosis is a cervical arterial variation that was initially reported, based on anatomic dissection, from Japan in 2000. The purpose of this report is to show the characteristic radiological findings of this extremely rare cervical arterial variation.

METHODS

We analyzed nine cases, including six previously reported cases and three cases that we recently experienced. Three of the six previously reported cases were from Japan, and the remaining three cases were from Korea. MR angiography (4), CT angiography (2), catheter angiography (2) and autopsy (1) were used as diagnostic modalities.

RESULTS

The study population included eight men and one woman. Anastomosis was seen on the left side in seven cases and the right side in two cases, and it was located at the level of the C1/2-C2/3 intervertebral space. In all cases, ECA was larger than the ICA at the level of their origins. In four cases, the ICA was extremely small in caliber. In one case, the ICA may have been occluded postnatally, and its configuration was similar to that of the nonbifurcating cervical carotid artery (CCA). With the exception of this occluded case, the carotid bifurcation and EC-ICA anastomosis formed a large arterial ring in all cases.

CONCLUSION

EC-ICA anastomosis can be regarded as a variant of the nonbifurcating CCA because if the most proximal segment of the small ICA is occluded, nonbifurcating CCA may form. EC-ICA anastomosis is located between the C1/2-C2/3 intervertebral space and may be formed by the remnants of the proatlantal artery I.

Radiological and Clinical Findings of Non-bifurcating Carotid Artery With Aberrant Course: A Case Report and Review of the Literature

A non-bifurcating carotid artery is a rare variation in the carotid circulation. Here we present a rare case of a non-bifurcating carotid artery with an aberrant course of the internal carotid artery incidentally discovered in a patient who presented to the trauma center after a fall. To our knowledge, this is the first reported case of a non-bifurcating carotid artery with an aberrant course of the internal carotid artery. The embryonic mechanisms of this variation and the available literature regarding this condition are also reviewed. Knowing this variation is necessary before considering vascular intervention of the neck and ear surgery to avoid vascular injury and complications.

Bilateral non-bifurcating carotid arteries in a patient with recurrent cerebrovascular events

Introduction

Among congenital anomalies of the carotid artery circulation, the presence of a non-bifurcating carotid artery is extremely rare. Relevant cases with unilateral non-bifurcating carotid artery have scarcely been described in the literature. After extensive literature review, only one case with asymptomatic bilateral non-bifurcating carotid arteries associated with persistent proatlantal artery was identified.

Methods

We present the case of a 40-year-old man with recurrent cerebrovascular events presenting non-bifurcating carotid arteries bilaterally.

Results

A 40-year-old man presented in the emergency department with a transient ischemic attack. Past medical history included prior ischemic stroke of unknown etiology in the distribution of the left middle cerebral artery, untreated hyperlipidemia and tobacco use. Complete work-up in order to identify the underlying mechanism of the patient’s recurrent cerebrovascular events was negative, except for the finding of non-bifurcating carotid arteries bilaterally, associated with an extensive intracranial anastomosing arterial network. Long-term antiplatelet therapy and statins were administered as secondary stroke prevention therapy.

Discussion

Previous reports suggest that non-bifurcating carotid arteries may be associated with atherosclerotic plaque formation in symptomatic cases due to shear stress, tortuosity or other local factors. However, in the absence of atherosclerosis, the pathogenic association of bilateral non-bifurcating carotid arteries with cerebrovascular events remains questionable, but may be considered when other stroke etiologies are excluded.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42466-021-00154-9.

Anomalous external carotid-internal carotid artery anastomosis diagnosed by computed tomography angiography: a case report

An anomalous anastomosis between the external and internal carotid arteries forming an arterial ring at the level of the cervical internal carotid artery is an extremely rare variant, and its embryological origin remains unclear. This report describes a rare arterial variation at the level of carotid bifurcation incidentally discovered in a 67-year-old man. Computed tomography angiography revealed an anomalous anastomosis between the external and internal carotid arteries at the level of the C2–3 intervertebral space with a small proximal cervical segment of the internal carotid artery and the occipital artery originating at this anomalous anastomosis. This report may be of embryological significance and contribute to understanding the mechanisms of carotid artery formation.

Stenting for Middle Cerebral Artery Stenosis Associated with a Nonbifurcating Cervical Carotid Artery: Case Report and Naming Consideration

BACKGROUND

A nonbifurcating cervical carotid artery (NBCCA) is a rare anatomic variation of the carotid artery which directly arises from the common carotid artery without forming a bifurcation. A rare case of an NBCCA associated with middle cerebral artery (MCA) stenosis is reported herein.

CASE DESCRIPTION

A 70-year-old man was admitted to the hospital for fresh infarctions in the left frontoparietal lobe. The angiographic imaging showed severe atherosclerotic stenosis in the left MCA associated with an ipsilateral NBCCA. The origin of the left internal carotid artery (ICA) was occluded leaving a stump. A tortuous anastomotic vessel arose from the external carotid artery and continued as the cervical ICA. A stent was placed in the left MCA, and the patient recovered uneventfully and without further ischemia during follow-up. Embryogenesis and naming considerations are briefly discussed.

CONCLUSIONS

This is the first report of an NBCCA accompanied by ipsilateral MCA stenosis. The name hypogenesis/agenesis of the proximal ICA might describe the congenital anatomic variation of an NBCCA more accurately than NBCCA.

Nonbifurcating Carotid Artery: A Case Report with a Review of Embryogenesis

Patient: Male, 66

Final Diagnosis: Nonbifurcating carotid artery

Symptoms: No symptoms

Medication: —

Clinical Procedure: —

Specialty: Neurology

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.