Rare carotid-vertebrobasilar anastomoses with notes on the differentiation between proatlantal and hypoglossal arteries

Disappearing Cerebral Communicating Vessels in Embryonic Development-With a Case of Carotid-Vertebrobasilar Artery Anastomosis

In early embryonic development, anastomoses between carotid and basilar arteries occur in the primitive trigeminal, primitive otic, primitive hypoglossal, and primitive proatlantal arteries, and these anastomoses gradually disappear as the embryo continues to develop. This article reported a case of vascular anastomosis occurring between the external carotid artery and vertebral artery.

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.

A rare case report: bilateral occipital artery arising from the vertebral artery

BACKGROUND

Variations of the origin of the occipital artery (OA) can be considered as congenital anomalies that are often asymptomatic and detected incidentally on angiography or during cadaver dissection. While OA normally originates from the posterior aspect of the external carotid artery (ECA), recent evidence also reflects that OA may infrequently originate from the internal carotid artery (ICA); however, OA originating from the vertebral artery (VA) is a highly rare phenomenon.

CASE PRESENTATION

In a 54-year-old female patient with the complaint of left hemiparesis, computed tomography (CT) angiography revealed nonstenotic calcified plaques at the beginning of right ICA where common carotid artery (CCA) bifurcates. We also incidentally observed that bilateral OA originated from the VA using maximum intensity projection (MIP) technique. In addition to this rare variation, CT angiography showed the osseous anomaly termed as high-riding VA (HRVA) in the C1/2 vertebral space of the V3 segment of the VA.

CONCLUSION

To the best of our knowledge, a case of bilateral OA originating from the VA has not been reported to date. We believe that recognition of this rare variation may contribute to the relevant literature and it is of importance to consider this variation in radiological imaging and surgical procedures involving this region.

Posterior circulation ischaemic stroke-a review part I: anatomy, aetiology and clinical presentations

Posterior circulation ischaemia is a clinicopathological condition with complex symptomatology associated with an infarction within the vertebrobasilar arterial system. Posterior circulation strokes account for about 20-25% of all ischemic strokes and remain a significant cause of patient disability and mortality. Diagnosis can be challenging because presenting symptoms are often non-focal and because there is a substantial overlap in symptoms and signs of ischaemia in the anterior circulation. Despite better imaging techniques, diagnosis and treatment of life-threatening conditions, such as basilar artery occlusions, are often delayed. Therefore, early detection of symptoms and causes of posterior circulation ischaemia is essential for choosing the most appropriate therapy. In this review, we summarise the anatomy, aetiology, typical presentations and characteristic findings of common strokes resulting from disease in the vertebrobasilar arterial system.

Isolation of right internal carotid artery, persistent proatlantal 1 artery and rete mirabile in a child with 22q11 deletion syndrome

We report a case of a 2-year-old girl with 22q11 deletion syndrome who underwent studies for cardiac murmur. Ultrasound, computed tomography angiography and digital subtraction angiography revealed an aberrant right subclavian artery and an isolated right internal carotid artery (ICA) originating from the right pulmonary artery. A right carotid rete mirabile (CRM) and a proatlantal (Pa) type 1 artery were also found. We hypothesize that Pa type 1 persistence and CRM development are secondary to the reversal of flow of the isolated ICA.

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.

A Functional Perspective on the Embryology and Anatomy of the Cerebral Blood Supply

The anatomy of the arterial system supplying blood to the brain can influence the development of arterial disease such as aneurysms, dolichoectasia and atherosclerosis. As the arteries supplying blood to the brain develop during embryogenesis, variation in their anatomy may occur and this variation may influence the development of arterial disease. Angiogenesis, which occurs mainly by sprouting of parent arteries, is the first stage at which variations can occur. At day 24 of embryological life, the internal carotid artery is the first artery to form and it provides all the blood required by the primitive brain. As the occipital region, brain stem and cerebellum enlarge; the internal carotid supply becomes insufficient, triggering the development of the posterior circulation. At this stage, the posterior circulation consists of a primitive mesh of arterial networks that originate from projection of penetrators from the distal carotid artery and more proximally from carotid-vertebrobasilar anastomoses. These anastomoses regress when the basilar artery and the vertebral arteries become independent from the internal carotid artery, but their persistence is not uncommon in adults (e.g., persistent trigeminal artery). Other common remnants of embryological development include fenestration or duplication (most commonly of the basilar artery), hypoplasia (typically of the posterior communicating artery) or agenesis (typically of the anterior communicating artery). Learning more about the hemodynamic consequence that these variants may have on the brain territories they supply may help understand better the underlying physiopathology of cerebral arterial remodeling and stroke in patients with these variants.

[Type II proatlantal artery with unusual origin of the occipital artery feeding of a type IV dural arteriovenous fistula: case report]

CASE REPORT

We report the case of a 49 year-old woman, who presented with an intracranial haemorrhage. During cerebral angiography investigations, we observed an unusual vertebral artery that originated from the external carotid artery and an uncommon origin of the occipital artery from the vertebral artery feeding a dural arteriovenous fistula grade IV. This rare vertebral artery origin is probably the remnant of a type II proatlantal artery. In addition, the origin of the occipital artery evoked a vascular development disease including a dural arteriovenous fistula which may be the result. These multiple vascular abnormalities could be explained by embryologic disorders.

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.

Bilateral persistent hypoglossal arteries: MRI findings

Persistence of foetal anastomoses between carotid and vertebrobasilar arteries is well recognised, but their bilateral presence is rare. We report a case of bilateral persistent hypoglossal arteries. Absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent MRI confirmed this and revealed persistent hypoglossal arteries that arose bilaterally from the cervical internal carotid artery, entered the cranium through the hypoglossal canal and joined the lower portion of the basilar artery.

Trigeminal artery: a review of normal and pathological features

OBJECTS

Carotid-vertebrobasilar anastomoses-the trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries-serve as transitory channels between primitive internal carotid arteries and bilateral longitudinal neural arterial plexus, which is the precursor of future basilar artery, when the human embryo reaches about 4-mm length.

MATERIAL AND METHODS

Normal and/or abnormal morphofunctional aspects of the prenatal and postnatal forms of the trigeminal artery are described according to personal and literature data. Many arteries of similar origin and course are also noted in the differential diagnosis of the trigeminal artery.

CONCLUSIONS

The persistent primitive trigeminal artery, as the most commonly carotid-vertebrobasilar anastomosis, has a reported incidence of 0.03-2.2% in the literature. There is female sex predilection, and it may be discovered in patients of any age, on either side, and in association with many vascular variants. Although the significance of persistent primitive trigeminal artery regarding the development of an aneurysm or association with another pathological condition may not be clear, its (ab)normal morphology is the inspiration for anatomists, especially for neurosurgeons, before planning diagnostic and therapeutic procedures.

Incidental finding of a proatlantal intersegmental artery. A case report

We describe the case of a 70-year-old woman who had a left proatlantal intersegmental artery disclosed during carotid artery angiography with the findings of carotid-basilar anastomosis which originated from the petrous segment of the ICA and was filling the horizontal segment of the vertebral artery. Awareness of this vascular variation can prevent morbidity and mortality associated with carotid ligation or carotid endarterectomy, especially when an incomplete circle of Willis is present.

Normal and abnormal embryology and development of the intracranial vascular system

The brain vascular system develops in such a way that it continuously adapts the supply of oxygen and other nutrients to the needs of the parenchyma. To accompany the developing brain vesicles, it evolves in several steps: superficial meningeal network first; intraventricular choroid plexuses which determine the arterial pattern; penetrating capillaries from the surface to the ventricular germinal matrix forming simple transcerebral arteriovenous loops; cortical capillaries last, mainly in the last trimester. The venous return becomes connected to both the surface and to the choroidal veins, so forming distinct meningeal and subependymal venous drainage systems, while the arteries are on the surface only. While the arterial system was determined early (week 8), the venous system is continuously remodeled by the morphological changes of the base of the skull and the expansion of the brain vesicles. Until late in gestation, the vascular system is made of simple endothelial channels in which the arterial or venous fate is determined primarily by the direction of flow.

Persistent fetal intracranial arteries: a comprehensive review of anatomical and clinical significance

As fetal intracranial vessels may persist into adulthood, knowledge of their anatomy and potential clinical and surgical complications should be borne in mind by the surgeon. A comprehensive review of these vessels, however, is not easily identified in the literature. Therefore, the present analysis was undertaken so that such information is available to the clinician and morphologist.

Internal carotid and ipsilateral type II proatlantal artery stenoses causing simultaneous hemispheric and vertebrobasilar transient ischemia

A case of persistent proatlantal artery (PA) is described in a 60-year-old woman who presented with cerebellar ataxia, homonymous hemianopia, and aphasia. Both Doppler scan and magnetic resonance angiography (MRA) showed agenesis of both vertebral arteries, 80% stenosis of the left internal carotid artery (ICA), and an anastomotic vessel between the left external carotid artery (ECA) and the left vertebral artery (LVA) with a tight stenosis at the origin. It was thought to be a type II PA. Both lesions were successfully treated by ICA endarterectomy and common carotid artery to PA bypass. This case demonstrates the clinical significance of persistent PA in the evolution of an ischemic cerebrovascular disease.

An uncommon anastomosis of the posterior inferior cerebellar artery and the external carotid artery with the patent vertebrobasilar system

The hypoglossal artery arises as a branch of the internal carotid artery and traverses the hypoglossal canal. However, the hypoglossal artery arising from the external carotid artery (ECA) and connecting directly with the posterior inferior cerebellar artery (PICA), instead of the basilar artery or the vertebral artery, is very rare. We present a case of an uncommon variant of the hypoglossal artery arising from the ECA that connected directly with the PICA.

Giant cavernous aneurysm associated with a persistent trigeminal artery and persistent otic artery

Primitive trigeminal artery (PTA) and primitive otic artery (POA) is a very rare entity in adult life. We present a case of PTA and POA associated with a giant unruptured cavernous aneurysm in a 54-year-old woman. The PTA and the POA arose from the sac of the aneurysm directly, which greatly complicated endovascular therapy management.

Persistent hypoglossal artery detected incidentally in a hypertensive patient with intracerebral hemorrhage: a case report and review of the literature

A 73-year-old woman with a history of chronic hypertension admitted to our clinic with complaint of acute paresis in her left arm. Computed tomography and magnetic resonance imaging were performed to the patient which displayed intracerebral hemorrhage in the right parieto-occipital lobe. Further review of the computed tomography and magnetic resonance imaging scan showed an enlarged left hypoglossal canal with a large vessel passing through it. The patient was thereafter examined with cerebral digital subtraction angiography to determine the cause of hemorrhage, but no vascular etiology was demonstrated, except from a persistent hypoglossal artery. We present a rare case of persistent hypoglossal artery, which we detected incidentally during angiographic evaluation, with a review of the literature.

The right vertebral artery arising as a branch of the right internal carotid artery: report of a rare case

Atypical origins of the vertebral artery (VA) are rare anatomical findings. We present an extremely rare arrangement of the cerebral circulation in a 61-year-old male patient detected on magnetic resonance angiography, where the right VA arose as a direct branch of the cervical internal carotid artery (ICA). This likely reflects the failure of the pro-atlantal artery to regress during the third to fourth week of embryological life. Although the effect of the variant on symptomology is debateable, knowledge of the potential for the VA to arise as a branch of the ICA is pertinent to radiologists and surgeons operating on the great vessels and their branches, particularly vascular surgeons undertaking carotid endarterectomy.

Proatlantal intersegmental artery: a review of normal and pathological features

OBJECTS

Primitive carotid-vertebral and carotid-basilar anastomoses are formed early during human embryogenesis at approximately 24 days. From cephalic to caudal direction, these anastomoses are cranial extensions of the primitive internal carotid, trigeminal, otic, hypoglossal and proatlantal intersegmental arteries.

MATERIALS AND METHODS

Normal and/or abnormal morphofunctional aspects of prenatal and postnatal forms of the proatlantal intersegmental artery, from the 24th day of gestation to postnatal eight decades, are described according to personal and literature data. Many (ab) normal carotid-vertebral anastomoses are also marked in differential diagnosis of the proatlantal intersegmental artery.

CONCLUSIONS

The proatlantal intersegmental artery maintains the posterior circulation until the vertebral arteries are fully developed between the seventh and eighth gestational weeks. When this artery fails to obliterate, it becomes persistent one. The proatlantal intersegmental artery, most commonly, is an incidental finding or it may be of clinical significance in some patients.

Unusual variant of persistent primitive hypoglossal artery

Here, we present a case of an unusual variant of a persistent primitive hypoglossal artery, which was found incidentally during an examination for a hypertensive thalamic haemorrhage. The anastomotic vessel arose from the external carotid artery and joined the vertebral artery through the hypoglossal canal. The embryology of the anomaly is briefly discussed.

Ruptured aneurysm of a persistent primitive hypoglossal artery treated by endovascular approach—case report and literature review

BACKGROUND

A persistent PHA is the second most common of the embryonic carotid-basilar anastomoses that fail to regress in the embryo. The fact that PHA often is functionally a single artery providing blood to the posterior circulation poses challenging therapeutic problems in case of an aneurysm located on the PHA.

CASE DESCRIPTION

A 46-year-old woman presented with SAH due to a large ruptured aneurysm of the left PHA. Identification of such an artery by CT angiogram is the proposed cold standard. The aneurysm was obliterated by coil embolization. To our knowledge, this is the first reported case of aneurysm located on a primitive persistent hypoglossal artery that was endovascularly treated.

CONCLUSION

Aneurysms located on a persistent PHA can be treated safely and effectively via an endovascular approach.

Bilateral occipital infarcts associated with carotid atherosclerosis and a persistent hypoglossal artery

The persistent hypoglossal artery (PHA) is the second most common persistent embryological carotid-basilar connection and usually represents an incidental finding in cerebral arteriograms. The hypoglossal artery connects the primordial carotid artery with the longitudinal neural arteries, which later form the basilar artery. The PHA leaves the internal carotid artery as an extracranial branch, enters the skull through the anterior condyloid foramen, the hypoglossal canal and joins the caudal portion of the basilar artery. We report magnetic resonance and digital subtraction angiography findings in the first case of bilateral occipital infarctions associated with PHA and carotid atherosclerosis. The probable mechanism underlying bilateral occipital infarcts was embolism from the carotid territory to the posterior cerebral arteries. PHA may present a challenge in diagnosis and management of patients with carotid atherosclerosis and vertebrobasilar ischemia.

Cerebral Arteriovenous Malformation Embolized through Persistent Primitive Hypoglossal Artery: A Case Report

SUMMARY

Carotid-vertebral anastomoses are commonly detected as incidental findings. But sometimes these channels are important for the clinical condition of the patient. Here a case of right thalamo- capsular arteriovenous malformation is described where a persistent primitive hypoglossal artery was the only route for embolization of the arteriovenous malformation.

Vertebrocarotid collateral in extracranial carotid artery occlusions: digital subtraction angiography findings

The internal and external carotid arteries are usually considered occluded distal to a common carotid artery occlusion but some collateral vessels may provide blood keeping the internal and external carotid arteries patent distal to the occlusion. Most common communication in such a case is diversion of blood from muscular branches of the vertebral artery to occipital branch of the external carotid artery which in turn could maintain blood flow into the internal carotid artery, a condition called carotid steal. We encountered vertebrocarotid anastomoses maintaining the patency of carotid circulation in six patients. Patients were four females and two males, ages ranging from 40 to 67 (mean age: 56) years. Five of the patients had ischemic cerebral symptoms. The origin of the external carotid artery was occluded in two and the whole common carotid artery in the remaining four patients. Two patients had double steal, carotid and subclavian at the same time. There was also severe stenosis or occlusion of at least one other major extracranial cerebral artery in all the cases. This concomitant involvement of the second extracranial cerebral artery was thought to be the main reason for the development of vertebrocarotid collateral. In contrast to most of the previously published reports claiming the inadequacy of angiography when compared with colour Doppler ultrasonography, angiography finely depicted the distal patency of the carotid circulation and all the collaterals in detail in every case. Selective injection of the vertebral artery ipsilateral to the occlusion, is the key to demonstrate distal patency of the carotid circulation in cases of proximal carotid occlusion. Demonstration of patency of the distal circulation is very important because some of the patients might get benefit from a reconstructive surgery.

Persistent carotid-vertebrobasilar anastomoses

The persistent carotid-vertebrobasilar anastomoses (PCVBA) can be explained by an interruption of the vertebrobasilar system (VBS) embryogenesis. We present two very rare cases of persistent anastomoses: a hypoglossal artery and a type I proatlantal artery, insisting on the angiographic criteria allowing differentiation. After a brief review of the embryogenesis of the VBS, we describe the different types of persistent anastomoses (hypoglossal, type I and II proatlantal, trigeminal and otic arteries). We will insist on the potential risks, not well-known, but typical of each anastomosis. PCVBA usually are incidental findings but imaging follow-up may be required since aneurysms may develop.

Reevaluation of the Morphological Parameters according to 11 Different Duplications of the Fetal Vertebral Artery at Prevertebral (V1) and Intracranial (V4) Parts

It is noted that the vertebral artery lies buried in a sea of generalities, prejudices, fear, and ignorance in the clinical literature. This fact is the reason why this observation is based on 11 cases, selected from 206 fetal cases, of various duplications of the vertebral artery. Aberrant or anastomotic vessels are illustrated and their definition is largely modified according to the recent anatomic terminology. Duplications of the vertebral artery indicate the 'segmental duplication' as a first form, and the presence of an abnormal 'fenestra' in the vessel's trunk as a second form of duplication. There are 9 (5 at prevertebral and 4 at intracranial parts) or 4.36% cases of 'segmental duplication' of the vertebral artery and 2 or 0.98% 'arteria vertebralis unifenestrata' at the intracranial part of all 206 cases. Successive morphological parameters of aberrant or anastomotic vessels are described and discussed according to personal cases and cases in the literature.

Watershed infarcts in the fetal and neonatal brainstem. An aetiology of central hypoventilation, dysphagia, Möibius syndrome and micrognathia

Watershed zone infarcts of the human cerebral cortex at the overlapping junctions of the anterior and middle cerebral arterial territories are well known. Another watershed zone exists in the brainstem tegmentum, between the terminal perfusion zones of the paramedian penetrating and long circumferential arteries, which are paired segmental vessels arising from the basilar artery. The vertebrobasilar circulation achieves its mature configuration and caudorostral flow by 9 weeks gestation. Systemic hypotension and other conditions of reduced basilar perfusion in the fetus, either early or late in gestation, may result in symmetrical longitudinal columns of infarction in the midbrain and tegmentum of the pons and medulla oblongata and laminar necrosis of the midbrain tectum. Within this zone are cranial nerve nuclei III-XII, the nucleus and tractus solitarius or central pneumotaxic center, as well as the nucleus ambiguus and other somatic motor nuclei that subserve muscles of swallowing, mastication and tongue movement. Watershed infarcts in the human fetal and neonatal brainstem are clinically expressed as multiple cranial neuropathies, failure of central respiratory drive and apnea, dysphagia and aspiration, Möbius syndrome and Pierre Robin sequence. MRI is sometimes helpful, but most of the involved neuroanatomical structures are beneath the resolution of present imaging techniques, and the diagnosis during life depends upon clinical neurological examination of the neonate, sometimes supported by evoked potential studies. Postmortem examination confirms the diagnosis and dates the lesions, but also contributes to better understand transient or persistent vascular insufficiencies in the fetal and neonatal brainstem.

Primitive trigeminal artery variant aneurysm treated with Guglielmi detachable coils--case report

A 69-year-old woman had suffered from diplopia on right lateral gaze for the last 4 months due to right abducens nerve paresis. Right carotid angiography showed a cavernous internal carotid artery (ICA) aneurysm of 17 x 16 x 14 mm size and a primitive trigeminal artery (PTA) variant supplying the territory of the posterior inferior cerebellar artery. Intraluminal occlusion of the aneurysm was performed with 15 Guglielmi detachable coils. The flow of the PTA variant and the ICA was preserved. Right abducens nerve paresis improved partially. PTA variant is a primitive artery originating from the cavernous ICA supplying the cerebellum without opacification of the basilar artery. Only four of the 67 cases of PTA variant were associated with an aneurysm of the PTA variant. The possibility of this rare association should be considered when treating cavernous portion aneurysm because of the risk of cerebellar ischemia.

Carotid endarterectomy in rare bilateral carotid-vertebral anastomosis

In the embryo, the anterior and the posterior cerebral circulations are connected by several longitudinal anastomotic vessels. These anastomoses disappear progressively, until the carotid and vertebrobasilar systems are connected only by a pair of posterior communicating arteries. These embryonal anastomoses rarely persist in adults and may have an important physiologic role during carotid surgery. We report a case in which a patient with bilateral embryonal carotid-vertebral anastomoses underwent right carotid endarterectomy for asymptomatic internal carotid stenosis.

Endovascular treatment for a ruptured persistent trigeminal artery variant aneurysm on the distal portion--case report

A 71-year-old female presented with a rare case of ruptured aneurysm on the distal persistent trigeminal artery (PTA) variant trunk. The endovascular approach was used to successfully occlude the proximal PTA variant, as direct catheter approach to the PTA variant aneurysm on the distal portion was prevented by the tortuous course of the vessel. She was discharged without neurological deficit.

Carotid endarterectomy in the presence of a persistent hypoglossal artery: case report

OBJECTIVE AND IMPORTANCE

A persistent hypoglossal artery, one of the embryonic carotid-basilar anastomoses that can fail to regress in the embryo and can be observed past birth, is one of the only congenital anatomic variations of the internal carotid artery (ICA) that can complicate the performance of carotid endarterectomy. When associated with atherosclerotic carotid artery disease, the recognition and intraoperative management of a persistent hypoglossal artery is important.

CLINICAL PRESENTATION

A 72-year-old man presented with a symptom of transient right hemisphere ischemia, and although ultrasonography indicated a right ICA stenosis (and no other abnormality), angiography also demonstrated that the atherosclerotic plaque extended into the origin of a large right persistent hypoglossal artery arising 1.5 cm from the origin of the ICA. In this patient, the persistent hypoglossal artery was the only arterial supply to the basilar artery.

INTERVENTION

The patient underwent a right ICA endarterectomy, and intraoperative angiography was necessary to ensure that the persistent hypoglossal artery was the vessel shunted during the arterial repair.

CONCLUSION

Recognition of the primitive carotid-basilar anastomoses is important to surgeons who perform carotid endarterectomy and is not possible with ultrasonography alone. Intraoperative angiography enables the surgeon to accurately catheterize a persistent hypoglossal artery with a carotid shunt.

Primitive persistent carotid-basilar and carotid-vertebral anastomoses: a report of seven cases and a review of the literature

The persistence of embryonic carotid-basilar and carotid-vertebral anastomoses was investigated retrospectively in 4,400 cerebral angiograms. Six primitive persistent carotid-basilar anastomoses and one primitive persistent carotid-vertebral anastomosis were found. In 4,400 cerebral angiograms, the incidence of primitive carotid-basilar and carotid-vertebral anastomoses was 0.14% and 0.023% respectively. Primitive persistent anastomoses are associated with intracranial vascular anomalies, especially aneurysms. The clinical and pathological findings in combination with these primitive persistent anastomoses were also examined.

Persistent hypoglossal artery: diagnostic and therapeutic considerations concerning carotid thromboendarterectomy

Fetal anastomotic connections between the developing internal carotid and basilar arterial systems are via the three presegmental arteries: the otic artery, the hypoglossal artery, and the trigeminal artery. After formation of the posterior communicating artery from the caudal branch of the internal carotid artery, the presegmental arteries are generally obliterated. Rarely, however, these primitive carotid-basilar anastomoses will persist into adult life, and may be detected as incidental findings at the time of cerebral angiography during evaluation of the patient with suspected cerebrovascular disease. In addition, persistence of such anastomoses may result in the coexistence of anterior and posterior circulation symptoms, precipitating diagnostic confusion. Two patients with symptoms and persistent hypoglossal artery undergoing carotid thromboendarterectomy are discussed, with emphasis on clinical presentation, diagnostic criteria and intraoperative management.

Persistent primitive proatlantal intersegmental artery (proatlantal artery I) results in 'top of the basilar' syndrome

BACKGROUND

Persistent primitive proatlantal intersegmental artery (proatlantal artery I) is an anastomotic channel between the carotid and vertebrobasilar arterial systems. Persistence of this embryonic anastomosis is very rare. The "top of the basilar" syndrome is usually due to occlusion of thalamoperforating arteries by emboli that rise from the vertebrobasilar arterial system. In this case, however, the emboli stemmed from atherosclerotic plaques in the carotid system.

CASE DESCRIPTION

A 55-year-old woman was hospitalized with top of the basilar syndrome. A brain scan showed hypodense lesions extending from the mesencephalon to both thalami. Digital subtraction angiography of the cerebral circulation was performed, which revealed a proatlantal artery I on the left side. In addition, atheromatous plaques were seen along the internal and common carotid arteries on the same side.

CONCLUSIONS

The occurrence of proatlantal artery I is extremely rare. Top of the basilar syndrome is also rarely encountered. To our knowledge, this is the first report of a patient with both conditions.

Right proatlantal artery type I, right internal carotid occlusion, and left internal carotid stenosis: case report and review of the literature

A 66-year-old man presented with right cerebellar infarction and ischemic lesions in the left dorsal thalamus and right upper parietal lobe. Angiography showed occlusion of the right internal carotid artery proximal to an ipsilateral proatlantal artery type I, 70% stenosis of the left internal carotid artery, and aplasia of both posterior communicating arteries. The carotid occlusion was successfully treated by thrombendarterectomy. Persistence of a proatlantal artery is a rare condition. In relation to the 38 literature reports on proatlantal arteries, this case demonstrates the clinical significance of a persistent proatlantal artery in the evolution of atypical ischemic cerebrovascular disease.

Persistent hypoglossal artery: An anomaly leading to false-positive carotid duplex sonography

Duplex ultrasonography is becoming increasingly popular as the sole diagnostic test in the evaluation of carotid artery bifurcation disease. We present a patient with a persistent hypoglossal artery, a rare primitive internal carotid-basilar anastomosis, masquerading as an internal carotid artery stenosis on ultrasound. The operative management of this anomaly is reviewed.

Persistent proatlantal artery associated with carotid artery stenosis treatment by percutaneous transluminal balloon angioplasty

A 58-year-old man had an asymptomatic tight stenosis of the internal carotid artery associated with a persistent proatlantal artery. This as well as other compositional arterial anomalies of the basilar artery were discovered on arteriograms. The stenosis was successfully treated by percutaneous transluminal balloon angioplasty. Therapeutic choices are discussed in this setting because of the risk of carotid clamping in the presence of persistent carotid-basilar anastomoses.

The carotid web: a developmental anomaly of the brachiocephalic system

A case of a congenital carotid web is reported. This lesion is believed to be a very rare anomaly of carotid development. The embryologic development of the brachiocephalic arteries is discussed. Anomalies of the brachiocephalic arteries including anomalies of origin from the aortic arch, atresia, and persistent communications between the carotid and vertebral system are reviewed.

Persistence of both proatlantal arteries with absence of vertebral arteries

A case of bilateral persistence of the proatlantal arteries with absence of both vertebral arteries proved by angiography is reported.

Proatlantal intersegmental artery and trigeminal artery associated with an aneurysm. Case report

A case of coexisting proatlantal intersegmental artery and primitive trigeminal artery is described. These anomalies were incidental findings in a patient with hemiparesis due to occlusion of the middle cerebral artery. The primitive trigeminal artery had an asymptomatic aneurysm at its origin from the internal carotid artery.

Proatlantal intersegmental artery with absence of bilateral vertebral arteries. Case report

A case of proatlantal intersegmental artery with absence of bilateral vertebral arteries is presented. This rare anomaly was accidentally encountered on angiography in a patient with a ruptured aneurysm of the anterior communicating artery.