Persistence of both proatlantal arteries with absence of vertebral arteries

Embryology of the vertebral artery and variants of the adult

The vertebral arteries represent in the adult the main blood supply of the posterior cranial fossa, even if they appear relatively late during the embryological life. We reviewed all the most important steps of the vertebral artery's embryological development and the most common variants that can occur in the adult. The aim of this review is to summarize the main events of the development of this artery and to give an embryological explication for the most common variants of this artery.

Occipital artery arising from the cervical internal carotid artery at the level of the C2 vertebral body: three cases detected utilizing magnetic resonance angiography

We incidentally observed the occipital artery (OA) arising from the cervical internal carotid artery (ICA) at the level of the C2 vertebral body on magnetic resonance (MR) angiography in three patients. In the rare case in which the OA arises from the ICA, it is generally at its origin. The OA arises from the cervical ICA when all but the distal part of the anastomosis of the primitive proatlantal artery between the ICA and vertebral artery persists. Careful review of MR angiographic images is important to detect rare arterial variations, and both partial maximum-intensity-projection images and source images aid their identification on MR angiography.

Type 2 persistent primitive proatlantal intersegmental artery, a rare variant of persistent carotid-vertebrobasilar anastomoses

We describe a 48-year-old man with type 2 persistent primitive proatlantal intersegmental artery found incidentally on imaging. It is one of the rare persistent carotid-vertebrobasilar anastomoses in which the anomalous vessel arises from the external carotid artery and enters the skull through the foramen magnum.

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.

Aberrant posterior inferior cerebellar artery injury with C1 lateral mass screw placement: a case report and review of the literature

BACKGROUND CONTEXT

Complications associated with C1 lateral mass screw placement are relatively infrequent. The most commonly feared complications include neural or vascular injury. Although both vertebral artery and internal carotid artery injuries have been discussed in the literature, there have been no reports of posterior inferior cerebellar artery (PICA) injury from C1 lateral mass screw placement. We report a case of patient who had a cerebellar stroke after C1 lateral mass screw placement, secondary to injury of an aberrant PICA.

PURPOSE

To describe the normal anatomy of the PICA, the anatomic variations previously reported in the literature, the sequela and symptoms of a patient with PICA injury, and the relevance to C1 lateral mass screw placement. No previous reports of PICA injury with a cerebellar stroke have been reported with C1 lateral mass screw instrumentation.

STUDY DESIGN

Case report and literature review.

METHODS

The patient underwent an Occiput-C6 posterior instrumentation for a pathologic fracture, secondary to multiple myeloma. In the postoperative period, the patient was found to have dysarthria, imbalance, and dysdiadochokinesia. Urgent computed tomography confirmed well placed C1 lateral mass screws. Magnetic resonance imaging/Magnetic Resonance Angiography showed an infarct in the PICA distribution with an abnormal variant of the PICA coursing extracranially around C1. Neurologic monitoring did not detect the injury intraoperatively.

RESULTS

The patient was treated with anticoagulation and he made a reasonable recovery from his stroke.

CONCLUSIONS

We report the first case of an aberrant PICA injured during a C1 lateral mass screw placement, resulting in a cerebellar stroke. Consideration should be given to abnormal PICA variation when placing C1 lateral mass screws.

Bilateral Type II Persistent Proatlantal Intersegmental Arteries

A 64-year-old man with treated hypertension presented with acute left arm and leg weakness. A brain magnetic resonance imaging (MRI) and neck magnetic resonance angiography (MRA) were performed. There was restricted diffusion in the right internal capsule posterior limb consistent with an acute lacunar infarct. The MRA demonstrated aplastic bilateral cervical vertebral arteries (V1 and V2 segments). bilaterally, a variant artery arose from the external carotid just above its origin, extended superiorly then medially, and forming the vertebral artery (V3 and V4 segments). bilaterally, the occipital artery arose from the variant artery at the juncture where it turned medially. The right variant artery terminated intracranially in the right posterior inferior cerebellar artery. The left variant artery continued intracranially to supply the basilar. The appearance was consistent with bilateral persistent proatlantal intersegmental arteries (PPIA) type II.

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.

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.

Cutaneous hemangioma associated with persistence of the trigeminal and both proatlantal arteries

The authors describe a girl who was evaluated at 7 years old because of facial segmental hemangioma associated with unilateral persistent trigeminal artery, bilateral proatlantal arteries, hypoplasia of 1 posterior cerebral artery, kinking of 1 internal carotid artery at 2 different levels, and transdural collateral vascularization supplying the posterior areas of the cerebral hemispheres. This is the first patient known to have a cutaneous hemangioma associated with bilateral proatlantal arteries despite having a unilateral facial hemangioma.

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.

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.

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.