Type II proatlantal artery (occipital subtype) with bilateral absence of the vertebral arteries

The Vertebral Artery: A Systematic Review and a Meta-Analysis of the Current Literature

(1) Background. The anatomical variations of the vertebral arteries (VAs) have a significant impact both in neurosurgery and forensic pathology. The purpose of this study was to evaluate the variational anatomy of the vertebral artery. We evaluated anatomical aspects regarding the V1 and V2 segments of the VA: origin, course, tortuosity, hypoplasia, and dominance, and established the prevalence of each variation. (2) Methods. We conducted a systematic search in PubMed and Google Scholar databases, up to December 2022. Sixty-two studies, comprising 32,153 vessels, were included in the current meta-analysis. We used a random-effects model with a DerSimonian-Laird estimator. The confidence intervals were set at 95%. The heterogeneity between studies was assessed using I². The funnel plot and Egger's regression test for plot asymmetry were used for the evaluation of publication bias. Statistical significance was considered at p < 0.05. (3) Results. The most common site for the origin of both VAs was the subclavian artery. The aortic arch origin of the left VA had a prevalence of 4.81%. Other origins of the right VAs were noted: aortic arch (0.1%), right common carotid artery (0.1%), and brachiocephalic trunk (0.5%). Ninety-two percent of the VAs entered the transverse foramen (TF) of the C6 vertebra, followed by C5, C7, C4, and least frequently, C3 (0.1%). Roughly one out of four (25.9%) VAs presented a sort of tortuosity, the transversal one representing the most common variant. Hypoplasia occurred in 7.94% of the vessels. Left VA dominance (36.1%) is more common, compared to right VA dominance (25.3%). (4) Conclusions. The anatomy of the VA is highly irregular, and eventual intraoperative complications may be life-threatening. The prevalence of VA origin from the subclavian artery is 94.1%, 92.0% of the VAs entered the TF at C6, 26.6% were tortuous, and 7.94% were hypoplastic.

Type 2 left proatlantal artery with normal left vertebral artery and association with an aberrant right subclavian artery and a bi-carotid trunk

Type 2 proatlantal artery (PA) is a rare type of the carotid-vertebrobasilar anastomosis that arises from the external carotid artery and enters the posterior fossa via the foramen magnum (FM). The type 2 PA is usually large and takes a similar course to the occipital artery (OA). The peripheral branch of the OA arises from the distal segment, just proximal to the FM. The ipsilateral vertebral artery (VA) is usually aplastic or hypo-plastic. We diagnosed a case of relatively small type 2 left PA in a patient with a normally developed ipsilateral VA. Furthermore, the patient had an aberrant right subclavian artery associated with a bi-carotid trunk. The combination of these extracranial arterial variations has not been reported in the relevant English language literature.

Clinical importance of the occipital artery in vascular lesions: A review of the literature

The occipital artery (OA) is a critical artery in vascular lesions. However, a comprehensive review of the importance of the OA is currently lacking. In this study, we used the PubMed database to perform a review of the literature on the OA to increase our understanding of its role in vascular lesions. We also provided our typical cases to illustrate the importance of the OA. The OA has several variations. For example, it may arise from the internal carotid artery or anastomose with the vertebral artery. Therefore, the OA may provide a crucial collateral vascular supply source and should be preserved in these cases. The OA is a good donor artery. Consequently, it is used in extra- to intracranial bypasses for moyamoya disease (MMD) or aneurysms. The OA can be involved in dural arteriovenous fistula (DAVF) and is a feasible artery for the embolisation of DAVF. True aneurysms and pseudoaneurysms can occur in the OA; surgical resection and embolisation are the effective treatment approaches. Direct high-flow AVF can occur in the OA; embolisation treatment is a good option in such cases. The OA can also be involved in MMD and brain arteriovenous malformation (AVM) by forming transdural collaterals. For a patient in the prone position, if occipital and suboccipital craniotomies are performed, the OA can also be used for intraoperative angiography. In brief, the OA is a very important artery in vascular lesions.

A rare case report of a mixed persistent proatlantal intersegmental artery

Adults with persistent proatlantal intersegmental artery (PPIA) are rarely seen. We present a case of a special type of PPIA that was in a 57-year-old man who presented with dizziness and episodic vertigo of 9 months duration. The diagnosis relied on computed tomography angiography and digital subtraction angiography, by which a left internal carotid artery stenosis and an ipsilateral PPIA originating from the external carotid artery (ECA) was found. This special type of PPIA can be described as a ''mixed PPIA'' that originated as Type II from the ECA and coursed as Type I. The patient underwent carotid artery stenting and had no relapse during 3 months follow-up. In addition, the literatures on PPIA were reviewed.

A systematic classification of the vertebral artery variable origin: clinical and surgical implications

Several congenital anomalies regarding the right (RVA) and left (LVA) vertebral artery have been described. The current paper aims to perform a systematic literature review of the variable vertebral artery (VA) origin from the aortic arch (AOA) and its branches. The incidence of these variants and the ensuing AOA branching pattern are highlighted. Atypical origin cases were found more commonly unilaterally, while LVA presented the majority of the aberrancies. The LVA emersion from the AOA (3.6%) and the RVA from the right common carotid artery (RCCA) (0.14%) were the commonest origin variations. Aberrant RVA origin as last branch of the AOA is very rare. Eighteen cases (0.12%) with an aberrant right subclavian artery (ARSCA) were found. Among them, the RVA originated from the RCCA and right subclavian artery in 94.4 and 5.6%, respectively. Sporadic cases had an AOA origin bilaterally; RVA and LVA had a double origin in 0.027 and 0.11%, respectively. A dual origin was detected in 0.0069%, bilaterally. The atypical VA origin may coexist with: (i) an ARSCA, (ii) a common origin of brachiocephalic artery and left common carotid artery (the misnomer bovine arch) and (iii) a bicarotid trunk. The aberrant VA origin favors hemodynamic alterations, predisposing to cerebrovascular disorders and intracranial aneurysm formation. Detailed information of VA variants is crucial for both endovascular interventionists and diagnostic radiologists involved in the treatment of patients with cerebrovascular disease. Such information may prove useful to minimize the risk of VA injury in several procedures.

Unilateral Aplasia versus Bilateral Aplasia of the Vertebral Artery: A Review of Associated Abnormalities

Morphological characteristics of 108 cases of uni- and bilateral aplasia of the vertebral artery (VA) in reports or images of retrospective studies, including one recent case, published between 1967 and 2016 are analyzed. Incidence, gender, persistence of carotid-vertebrobasilar anastomosis (CVBA), associated with other vascular variants, and vascular pathology in each group of uni- and bilateral VA aplasia are mutually compared. Most of the cases of VA aplasia in ages 31 to 80 were discovered in USA, Japan, and India. The bilateral VA aplasia is more common in the male gender than in the female one. The side of the VA aplasia had a significant effect on the side of CVBA persistence. Associated aplasia of other arteries was more common in cases of unilateral VA aplasia. The left VA was more commonly hypoplastic in cases of single right VA aplasia than the right VA in cases of single left VA aplasia. Aneurysms of definitive arteries were more frequent in cases of single right VA aplasia than in cases of single left VA aplasia. We claim that the aplasia of the VA probably depends on genetic factors in some races, while diseases are expressed usually in persons over 30 years of age.

Anastomosis of the external carotid artery and the V3 segment of the vertebral artery (presumed persistent second cervical intersegmental artery) diagnosed by CT angiography

Congenital anastomosis of the external carotid (ECA) and vertebral (VA) arteries is extremely rare. We report a case of right ECA-VA anastomosis diagnosed by computed tomography (CT) angiography. The presumed dilated ascending pharyngeal artery coursed posteriorly and entered the C1 right transverse foramen. The proximal right VA was aplastic, and the C2 right transverse foramen was absent. Based on these findings, we diagnosed congenital anastomosis of the ECA and V3 segment of the VA, which we presumed to represent persistence of the second cervical intersegmental artery. Detection of rare variations of the vertebral arteries requires careful observation of CT angiography with bone images and source images, especially to identify the level of entry into the transverse foramen. Correct diagnosis of anastomosis is important when intravascular embolization or infusion chemotherapy or surgical ligation of the ECA is planned.

A Previously Unreported Arterial Variant of the Suboccipital Region Based on Cadaveric Dissection

Introduction Several arterial variants have been reported to occur around the posterior arch of the atlas. Understanding the various anomalies and diagnosing them preoperatively can dramatically reduce the risk of surgical insult during neurosurgical procedures. Herein we report a case of an arterial variant found just below the posterior arch of C1. Case Report During the routine dissection of the suboccipital region via a posterior approach, an unusual bulge was identified just inferior to the inferior capitis oblique muscle. With further dissection, the structure was identified as a tortuous internal carotid artery. Conclusion Arterial variants around the posterior arch of C1 are surgically significant and can result in catastrophic injuries if unappreciated. Most of these variants will be related to the vertebral artery. To our knowledge, an arterial variant of the internal carotid artery in this location, as reported herein, has not been previously reported.

Arterial variations around the atlas: a comprehensive review for avoiding neurosurgical complications

INTRODUCTION

Neurosurgical approaches often involve the atlas. Therefore, the arterial relationships and anatomical variations are of paramount importance to the neurosurgeon.

METHODS

Using standard search engines, a literature review of arterial variants near the first cervical vertebra was performed.

CONCLUSIONS

Arterial variations around the atlas are surgically significant. Awareness of their existence and course may provide better pre-operative planning and surgical intervention, potentially leading to better clinical outcomes. Three-dimensional computed tomography angiography (3D CTA) is an important tool for identifying and diagnosing such abnormalities and should be used when such vascular anomalies are suspected.

Monolateral type I proatlantal artery with bilateral absence of vertebral arteries: description of a case and review of the literature

We report a case of a patient with right type I proatlantal intersegmental artery associated with right fetal posterior cerebral artery and absence of both vertebral arteries and of the left posterior communicating artery. We also describe the clinical relevance of these findings for this patient. A 56-year-old woman with vertigo and tinnitus underwent contrast enhanced Magnetic Resonance Angiography (MRA) of the supra-aortic arteries using a 1.5 Tesla scanner. Maximum intensity projection and volume rendering reconstructions were obtained. MRA demonstrated the persistence of an anastomotic artery between the right internal carotid artery and basilar artery, passing through the foramen magnum, suggesting a type I proatlantal intersegmental artery. The examination also showed the absence of both vertebral arteries and the presence of a right fetal-type posterior cerebral artery. To our knowledge, this is the first report of a type I proatlantal intersegmental artery associated with an omolateral fetal-type posterior cerebral artery and the absence of both vertebral arteries and of the left posterior communicating artery. This condition requires a watchful monitoring of the patient and has to be considered in case of surgical procedures of the carotid arteries.

External carotid dissection and external carotid proatlantal intersegmental artery with subclavian steal prompting external carotid and subclavian artery stenting

BACKGROUND AND PURPOSE

The authors describe a case of a proatlantal intersegmental artery seen in the setting of external carotid artery dissection and subclavian steal due to proximal subclavian artery stenosis.

METHODS

An 83-year-old woman presented with left homonymous hemianopsia and a right posterior cerebral artery distribution stroke. She was found to have severe left subclavian artery stenosis proximal to the vertebral artery (VA) and an occluded contralateral VA. Doppler ultrasonography and angiography both showed a dissection of the proximal left external carotid artery. Left common carotid artery angiography also demonstrated a connection between the external carotid and vertebral arteries at the C1 level with anterograde flow into the vertebrobasilar system and retrograde flow toward the vertebral origin, consistent with subclavian steal.

RESULTS

The patient underwent successful stenting of the subclavian and external carotid arteries with resolution of anterograde flow in the left VA.

CONCLUSIONS

This case represents an interesting presentation of both subclavian steal and an external carotid artery to VA anastomosis. Also, the presence of a dissection of the external carotid artery represents a rare finding.

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.