Bilateral segmental regression of the carotid and vertebral arteries with rete compensation in a Western patient

Applied anatomy of the vertebral arteries for endovascular neurointerventions

The vertebral arteries (VAs) constitute most of the arterial supply to the posterior cerebral vascular circulation. They have anatomical specificities and may have variants that are critical for neurointerventionists to recognize in order to design open or endovascular surgical treatment. This review addresses each segment of the VA including its origin and discusses the branches and relevant anatomical features for neurointerventions.

Composition of encephalic arteries and origin of the basilar artery are different between vertebrates

Intracranial arterial anatomy is lacking for most mammalian and non-mammalian model species, especially concerning the origin of the basilar artery (BA). Enhancing the knowledge of this anatomy can improve animal models and help understanding anatomical variations in humans. We have studied encephalic arteries in three different species of birds and eight different species of mammals using formalin-fixed brains injected with arterial red latex. Our results and literature analysis indicate that, for all vertebrates, the internal carotid artery (ICA) supplies the brain and divides into two branches: a cranial and a caudal branch. The difference between vertebrates lies in the caudal branch of the ICA. For non-mammalian, the caudal branch is the origin of the BA, and the vertebral artery (VA) is not involved in brain supply. For mammals, the VA supplies encephalic arteries in two different ways. In the first type of organization, mostly found in ungulates, the carotid rete mirabile supplies the encephalic arteries, the caudal branch is the origin of the BA, and the VA is indirectly involved in carotid rete mirabile blood supply. The second type of encephalic artery organization for mammals is the same as in humans. The caudal branch of the ICA serves as the posterior communicating artery, and the BA originates from both VAs. We believe that knowledge of comparative anatomy of encephalic arteries contributes to a better understanding of animal models applicable to surgical or radiological techniques. It improves the understanding of rare encephalic variations that may be present in humans.

Revised concept of rete-like collateral formation: Rete mirabile does not exist in humans

The carotid rete is a physiological network between the external and internal carotid arteries (ICA) in lower vertebrates. However, true carotid rete does not exist in humans. This review aimed to contrast the physiological function of human "rete-like collaterals" with that of lower vertebrate "rete mirabile". An explanation for the development of rete-like collaterals in human intracranial arteries was also discussed. The rete mirabile (carotid, vertebral, spinal, and thoracic) in lower vertebrates has a specific physiological role and does not form vasculature for the same purpose in humans. Therefore, the term "rete mirabile" should not be used for cases reported in humans. Instead, "rete-like collaterals" is preferred. In the literature, rete-like or arterial anastomosis was observed in the ICA cavernous portion and the intradural arteries. Based on the hypothesis of the segmental concept, it applies to the ICA and intracranial arteries. Whether in the ICA, middle cerebral artery, posterior cerebral artery, or posterior inferior cerebellar artery, the segmental concept is the same and should be considered to have formed secondary collaterals after segmental regress or dysgenesis of affected arteries. Summarily, the significance of this review lies in its reevaluation of vascular structures previously described as "carotid rete" in humans to a true and preferred term, "rete-like collaterals". It also provides insights into the historical context and potential genetic factors associated with the formation of arteries in humans, contributing to a better understanding of human vascular anatomy.

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.

Cerebrovascular disorders associated with agenesis of the internal carotid artery: Findings on digital subtraction angiography

Objective

Agenesis of the internal carotid artery (ICA) is a rare vascular condition that is complicated by intracranial aneurysms and rete mirabile. The altered hemodynamics caused by this distinctive cerebrovascular angioarchitecture can cause ischemic or hemorrhagic accidents. Data on clinical and radiographic features have been limited to describing this vascular pattern. We present five cases of agenesis of the internal carotid artery confirmed by digital subtraction angiography (DSA) and further investigate the influence of altered angioarchitecture on the integrity of intracranial morphology.

Methods

Cases of ICA anomalies were screened from the patients who underwent DSA in two hospitals. Clinical manifestation, radiographic features, management, and outcomes were retrospectively reviewed.

Results

Five patients [mean age 44 years (range, 30–65 years)] were included. Two patients presented with subarachnoid hemorrhage, one with cognitive impairment, one with dizziness, and one with intermittent headache. DSA demonstrated that three cases were complicated by intracranial aneurysms, one by dural arteriovenous fistula, and one by rete aneurysm. Three patients underwent endovascular treatment and one underwent bypass surgery. No patient died or experienced cerebrovascular accident during short-term follow-up.

Conclusions

ICA agenesis can be complicated by disorders such as intracranial aneurysm, rete aneurysm, and dural arteriovenous fistula. This suggests that ICA agenesis is associated with a tendency towards disrupted cerebrovascular homeostasis resulting from altered hemodynamics.

Lethal subarachnoid haemorrhage in a patient with rete mirabile network of the posterior circulation with associated aneurysm

Rete mirabile (RM), an arterial network normally existing in some vertebrate animals interconnecting the extracranial and intracranial arterial circulation, can rarely be found in humans whether asymptomatic or presenting with cerebral ischaemia or haemorrhage. Encompassing diverse angiographic characteristics and similarities with other arterial malformations, proper diagnosis and differential diagnosis is challenging. We hereby describe an unusual RM case variant, presenting to us with lethal subarachnoid haemorrhage owing to a ruptured small aneurysm associated with the RM network. Angiography disclosed an absent P1 segment of the posterior cerebral artery (PCA) and an RM network anastomosing the basilar apex with the normal distal PCA. Brain death was confirmed on the fifth day after admission and attributed to the severity of subarachnoid haemorrhage (SAH). This is an exceedingly rare case representing an intradural-to-intradural RM anastomosis in a patient presenting with lethal SAH. RM epidemiology, pathophysiology, presentation, angiographic findings and prognosis are reviewed.

Unilateral cervical and petrosal segment agenesis of the internal carotid artery with rete mirabile

The carotid rete mirabile (RM) is a physiological network between the internal and external carotid arterial systems. In this paper, an extremely rare case is presented, in which internal-external carotid artery anastomoses and a dilated ascending pharyngeal artery, due to unilateral agenesis of the cervical and petrous segments of the internal carotid artery (ICA), is presented.

Rete mirabile of posterior inferior cerebellar artery: A rare cause of subarachnoid hemorrhage

Rete mirabile is a congenital aberrant arterial collateral network resulting from abnormal embryonic activity during native vessel formation. Even though frequently observed in mammals, this entity is rare in humans except when there is hypoplasia, aplasia or narrowing of native vessels. Rete mirabile is reported involving internal carotid and vertebral arteries. Rete mirabile of the posterior inferior cerebellar artery (PICA) is not described in the literature. We report the clinical presentation, imaging findings and management of PICA rete mirabile formation with subarachnoid hemorrhage.

Rete mirabile of the ICA: Report of three cases

Carotid rete mirabile is an arterial meshwork, occurring at the cavernous portion of the internal carotid artery (ICA). Rete mirabile in humans is not present during normal development of the intracranial circulation and hence is considered as a collateral pathway that develops as a consequence of segmental agenesis of the ICA. We report three cases of this rare entity encountered at our institute.

Congenital absence of the bilateral internal carotid artery: a review of the associated (ab)normalities from a newborn status to the eighth decade of life

PURPOSE

Due to the fact that the internal carotid artery (ICA) is responsible for nourishing two thirds of the brain volume, our aim was to inspect the morphofunctional consequences of the bilateral lack of this artery.

METHODS

In order to examine this condition, we referred to both the library archive of our Faculty of Medicine and electronic databases of anatomical and clinical reports that included the following keywords: "absence," "aplasia," or "agenesis" in combination with "internal carotid artery," "common carotid artery," or only "carotid artery."

RESULT

We found 60 recorded cases of the bilateral ICA absence in the subjects of newborn status to the eighth decade of life, which had been discovered in 20 countries. The following ten parameters were described: the embryological base, terminology, history, incidence, general data, differential diagnosis, collateral circulation, the associated vascular aplasia and/or other variants, pathophysiology, and the importance in praxis.

CONCLUSION

This review noted all the cases of the bilateral ICA aplasia published for the past 104 years. Although there were 11.6% of cases of the associated cerebral aneurysms and 1-4 cases of 16 other diseases, approximately one quarter of the cases was without any pathology.

Rete mirabile associated with pial arteriovenous fistula: imaging features with literature review

A rete mirabile is a vascular network of intercommunicating small arteries or arterioles that replace the definitive adult artery supplying the brain. It supplies the brain in lower mammals but is not seen in normal human embryological development. A 26-year-old man presented with worsening tinnitus that was interfering with his sleep. On CT and digital subtraction angiography he was found to have a temporal lobe pial arteriovenous fistula with bilateral carotid and vertebral rete mirabile. The patient was offered open surgical and endovascular treatment options for pial arteriovenous fistula but he refused both and opted for conservative medical management. At 6-month follow-up he continued to have pulsatile tinnitus but was otherwise neurologically normal. We present the first described association of rete mirabile with pial arteriovenous fistula and discuss its clinical presentation and imaging features, with a review of the literature for bilateral carotid and vertebral rete mirabile.

Stenting for symptomatic vertebral artery stenosis associated with bilateral carotid rete mirabile: the long-term clinical and angiographic outcome

Symptomatic vertebral artery (VA) stenosis associated with bilateral carotid rete mirabile (CRM) has not been reported. We report the long-term clinical and angiographic outcome after stenting for symptomatic VA stenosis in the patient with bilateral CRM. This report is the first case that symptomatic VA stenosis associated with bilateral CRM was treated with stenting.

Carotid rete mirabile associated with subarachnoid hemorrhage from intracranial aneurysm: A case report and systematic review

Carotid rete mirabile (CRM) is a rare physiological vascular network in humans that is most often found in Eastern populations. This paper describes a CRM associated with an aneurysmal subarachnoid hemorrhage (aSAH) and discusses the details of the patient's treatment. A 28-year-old woman was admitted to our service with clinical signs and symptoms of a spontaneous aSAH. Computed tomography revealed a diffuse and extensive SAH (Fisher group IV), while an angiogram showed an abnormal collateral network in the right carotid system and a hypoplastic aspect to the internal carotid artery (ICA) on the same side. In addition, a saccular aneurysm with a diameter of 9.5 mm was present in the ophthalmic segment of the left ICA. This case is extremely uncommon. To avoid rebleeding in the patient, we successfully treated the patient by clipping the aneurysmal lesion. No procedure was performed for the CRM.

Bilateral carotid and vertebral rete mirabile with vein of Galen aneurysmal malformation: an unreported association

Rete mirabile is a fine meshwork of anastomosing vessels that replace the parent artery. A 30-year-old woman complained of slurring of speech, right eye proptosis, recurrent vomiting, and loss of bladder and bowel control, followed by drowsiness lasting 30-40 min, for the past 6 months. On cross sectional imaging and angiography, the patient was found to have a vein of Galen aneurysmal malformation, with bilateral carotid and vertebral rete mirabile. The patient was offered both endovascular and open surgical options but she refused any form of surgical treatment and opted for conservative management. At the 6 month follow-up, she continued to have occasional episodes of headache and vomiting but was otherwise normal. We describe the clinical, cross sectional, and angiographic features of this patient. A comparison with other patients with bilateral carotid and vertebral rete mirabile is also reported.

Bilateral carotid and vertebral rete mirabile presenting with subarachnoid hemorrhage caused by the rupture of spinal artery aneurysm

Rete mirabile (or carotid rete) is a normal structure that plays physiological roles in the lower mammals. However, the rete does not exist in the normal carotid circulation of humans. Carotid rete mirabile (CRM) is a rare condition compensating for congenital dysplastic internal carotid artery. Arterial plexus at the cavernous region, which supplies intradural internal carotid artery instead of the aplastic cavernous portion of internal carotid artery, looks like the "rete mirabile" seen in the lower mammals, and is a characteristic angiographical finding of CRM. In addition to the CRM, existence of segmental occlusion and tortuous collaterals of vertebral artery, so-called carotid and vertebral rete mirabile (CVRM), is a very rare condition. We report a 70-year-old female patient with bilateral CVRM presenting with subarachnoid hemorrhage (SAH) caused by the rupture of a cervical spinal artery aneurysm. Our patient is the oldest, compared with the previously reported four patients with CVRM. Moreover, this is the first report of ruptured spinal artery aneurysm as a cause of SAH associated with CRM/CVRM. To avoid rebleeding in the patient, we successfully treated the patients by performing coil embolization of the remaining spinal aneurysms. In patients with CVRM, aneurysm formation of the cervical spinal artery may be a reasonable consequence because of the hemodynamic stress on the spinal artery as a collateral pathway. Detailed evaluation of the cervical spinal arteries should be performed to detect or to rule out ruptured aneurysm in patients with SAH associated with CVRM.

Bilateral segmental agenesis of carotid and vertebral arteries with rete mirabile and the prominent anterior and posterior spinal arteries as compensations

Agenesis of carotid or vertebrobasilar arteries with rete formation is rare. The anterior spinal artery or posterior spinal arteries supplying the posterior circulation with steno-occlusion or agenesis of bilateral vertebral arteries is also uncommon. Here, we describe a very rare case of concomitant segmental agenesis of bilateral carotid and vertebral arteries with collateral compensations from the prominent anterior spinal artery and posterior spinal arteries, as well as some transdural arterial networks which were considered a rete mirabile. We discuss its embryological and anatomic significance.

Unilateral rete mirabile as a result of segmental agenesis of the ascending petrous segment of the internal carotid artery: embryology, differential diagnosis and clinical implications

We describe an extremely rare case of unilateral rete mirabile in a young woman and discuss its significance in embryological development as well as its radiological aspects, differential diagnosis and potential clinical implications.

Bilateral carotid and vertebral rete mirabile presenting with a prominent anterior spinal artery mimicking a spinal dural AV fistula at MRI

Bilateral carotid and vertebral rete mirabile (CVRM) is a very rare condition. We report a new case of CVRM initially detected by magnetic resonance imaging (MRI) of the cervical spine. MRI demonstrated tortuous vascular signal voids limited to the anterior cerebrospinal fluid space mimicking spinal dural arteriovenous fistula. A diagnosis of CVRM was confirmed on the basis of angiographic findings of rete formation associated with bilateral aplasia of the cavernous internal carotid and vertebral arteries without abnormal arteriovenous connection.

Asymptomatic carotid rete mirabile and contralateral carotid agenesis: a case report

Carotid rete mirabile (CRM) is a physiological network between the external carotid artery (ECA) and internal carotid artery (ICA) in lower mammals. It is a transdural arterial network centered at the parasellar area, in anatomical localization of intracavernous or petrous segment of ICA, associated with hypoplasia or absence of the cervical or petrous segment of ICA. It clinically presents as hemorrhagic or ischemic cerebrovascular disorder. Carotid rete mirabile have an angiographic frequency of 0.01%. The authors present a new case of right ICA agenesis supported by primary collateral channels associated with left hypoplasic ICA and CRM. It is an unusual entity and we highlight the role of CRM in cerebral hemodynamic in this asymptomatic vascular patient. Our aim is detail the angiographic features and diagnosis criteria of CRM.

A new pattern of arterial rete compensation of segmental basilar agenesis associated with carotid retia mirabilia: a case report (2010: 1b)

The carotid rete mirabile is a transdural arterial network centered at the parasellar area, in place of the intracavernous internal carotid artery (ICA), associated with hypoplasia or absence of the cervical and petrous ICA. Rare cases of vertebral rete mirabile associated with segmental agenesis of transdural vertebral arteries have been reported before. The authors present a new case of carotid rete mirabilia associated with segmental basilar agenesis compensated by a previously unknown pattern of arterial rete. Collateral flow, its efficacy and differential diagnosis are discussed.

Ophthalmic rete mirabile: the first angiographic documentation of embryonic ophthalmic collaterals in a patient with moyamoya disease. A case report

SUMMARY

Plexiform vascular networks of the rete mirabile in humans are rare but can be observed in some vertebrates such as cobaye, cat, cow and sheep. Each set of embryonic arteries can be a potential source of these vascular networks which reconstitute the distal flows in segmental agenesis of internal carotid or vertebral arteries especially in patients with PHACE (posterior fossa malformation of the brain, facial hemangiomas, arterial anomalies, cardiac anomalies with coarctation of aorta, and eye abnormalities) syndrome. Ophthalmic rete mirabile has been found in some mammals such as camel, deer and avian species of pigeon, Hawaiian seabirds and deep-water fish of the cod other than human. We describe the first human case of ophthalmic rete mirabile confirmed on angiography in a patient with moyamoya disease. These findings are the first description in the English literature as far as we know. The clinical implications with moyamoya disease will be briefly discussed according to the embryologic development of cranial arteries.

[Rete compensation in agenesis of the internal carotid artery]

The term carotid rete mirabile refers to an anatomic structure common in several lower mammals (e.g., swine). The blood supply for the intracranial arteries originates from branches of the external carotid artery, predominantly the ascending pharyngeal and internal maxillary arteries. In these animals the intracranial internal carotid artery forms from a dense network of numerous converging, small-caliber vessels. An analogous structure is rarely found in humans. Associated with segmental agenesis of the internal carotid artery, so-called carotid rete mirabile can be observed. In it numerous tortuous vessels with a diameter of 1-2 mm are found along the expected course of the internal carotid artery and coming from branches of the external carotid artery. These vessels converge to the intradural paraclinoid segment of the internal carotid artery, which shows a normal diameter. This rare pattern of collateral supply to the brain is illustrated here on the basis of two clinical case histories. Both patients presented with aneurysmal subarachnoid hemorrhage. In one, histological examination of a vessel biopsy revealed medial fibromuscular dysplasia. In both patients the rete mirabile was found in only one carotid system. The affected carotid canal in the skull base was hypoplastic. Human carotid rete mirabile probably has no inherent pathologic significance, but its frequent association with other intra- and extracranial vascular pathologies should be kept in mind.

Carotid and vertebral rete mirabile in man presenting with intraparenchymal hemorrhage: a case report

Carotid and vertebral rete mirabile is an unusual segmental regression of both the cavernous carotid artery and transdural vertebral arteries with a network of collateral vessels seen rarely in human beings. We present a 57-year-old woman with carotid and vertebral rete mirabile who presented with an acute intraparenchymal hemorrhage. The majority of patients present with subarachnoid hemorrhage or ischemic stroke. This is the first case of a non-Asian patient presenting with an intraparenchymal hemorrhage. In this case report, we describe the clinical and angiographic features of this unusual entity.

Bilateral segmental agenesis of the vertebrobasilar junction: developmental and angiographic anatomy

BACKGROUND AND PURPOSE

Bilateral vertebrobasilar junction agenesis is an exceptional anatomic variation. This article explores the angiographic characteristics of this variant and its embryologic mechanisms.

MATERIALS AND METHODS

Two observations of bilateral agenesis of the vertebrobasilar junction are reported. A case of atheromatous disease of the vertebrobasilar junction is shown to highlight characteristics distinguishing such a lesion from the reported variant.

RESULTS

In the 2 reported cases, the distal segment of both vertebral arteries (VAs) and the proximal portion of the basilar artery (BA) were absent. In addition, distal connections of the BA with the posterior cerebral arteries (PCA) were also lacking. As a consequence, the remaining portion of the BA was isolated from its usual sources of blood supply, which was provided by a persistent carotid-basilar anastomosis.

CONCLUSION

The developmental mechanism underlying bilateral agenesis of the vertebrobasilar junction likely involves the anterior radicular artery of C1. This branch of the proatlantal artery normally becomes the adult distal VA and the proximal BA. The lack of cranial connection of the BA with the PCA may be secondary to the proximal vertebrobasilar agenesis and the resulting paucity of antegrade flow within the BA. Alternatively, the absence of both the proximal and distal connections of the BA could be the result of a similar, yet unknown, developmental mechanism. From a clinical standpoint, this vascular anomaly was discovered incidentally in our 2 patients, a finding consistent with the assumed congenital nature of the variant.

Pathologie neurovasculaire malformative de l'enfant: malformations anévrismales de la veine de Galien (MAVG), malformations artérioveineuses piales (MAVP), malformations des sinus duraux (MSD)

The purpose of this article is to give an overview of the cerebral and spinal cord pediatric malformations; we particularly describe three of them: Vein of Galen arteriovenous Malformation, Pial Arteriovenous Malformation, and Dural Sinus Malformation. We report the experience of Bicêtre since 1981 to 2003, with 317 VGAM, 302 Pial AVM and 30 DSM. We describe natural history, clinical and imaging features, endovascular management and the clinical and morphologic results. The clinical consequences of the VGAM and Pial AVM are systemic or cerebral. When they are cerebral they are mainly from hydrovenous type, as melting brain, or chronic hydrocephalus with calcifications and seizures. Depending of their angioarchitecture and amount of arteriovenous shunt, their gravity and the time of revealing are variable. Pial AVM, they carry the risk of hemorrhage, unlike VGAM. The presence of a fistula type should lead to suspect hereditary hemorrhagic telangiectasia. The main risk of DSM is hemorrhage due to thrombosis of the malformation, more than hydrovenous disorders. In VGAM, we obtain the complete cure of the shunt in 55% of case, and reduction of more than half of the shunt in 93.8%. Seventy-four percent of treated cases had a normal neurologic examination. DSM have a worse prognostic, and mortality is 38% despite treatment.

Anatomically specific clinical examination of the carotid arterial tree

Clinical examination of the carotid arterial system has traditionally been used as a non-specific screening tool of atherosclerotic pathology. Because it has not yet been shown to delineate the precise location and grade of stenosis, further imaging modalities, such as duplex ultrasound, digital subtraction angiography, computed tomography and magnetic resonance, are currently used to obtain this information. These, however, have been shown to be susceptible to inaccuracies. Herein, a new protocol for bedside clinical examination that may define anatomical locality and degree of disease is presented. This consists of palpating the carotid pulse and auscultating for bruits along the course of the common carotid, internal carotid and external carotid arteries, as defined by surface anatomical landmarks from the lower neck to the pharynx. This protocol is not to replace more conventional methods of disease assessment but, in an era of diminishing clinical skills, may add to the overall evaluation of the pathological carotid tree.

A case of carotid rete mirabile associated with basilar tip aneurysm

SUMMARY

Carotid rete mirabile (CRM) is a rare condition consisting of a physiological network between the external and internal carotid arteries in lower vertebrates. Only a few cases have been reported in humans presenting as hemorrhagic or ischemic cerebrovascular disorder. We present a case of CRM presenting as an aneurysmal subarachnoid hemorrhage and discuss the embryologic, anatomic, hemodynamic and clinical significance of this rare entity.

Bilateral segmental absence of the internal carotid artery with rete compensation associated with absence of basilar artery: case report

BACKGROUND

Bilateral ICA absence is a rare lesion. Collateral circulation to the middle and anterior cerebral arteries in the absence of one or both ICAs may develop transcranial anastomoses from the external carotid system, a so-called CRM. Very rarely, theses arterial channels are observed in humans.

CASE DESCRIPTION

In the following case study, a 38-year-old man presented himself. He had a headache and scalp laceration after having had an accident. A right external carotid angiography identified anastomoses to distal intracranial vessel through the internal maxillary artery, but the intracranial vessels were only faintly visible. A right ascending pharyngeal arteriography showed an abnormal course and anastomoses with the intracranial vessel. The right ICA was absent. The left external carotid angiography demonstrated a network of tortous arteries in the region of the cavernous and petrous portion of ICA. The plexus of vessels on the left side communicated with the proximal part of the cavernous segment of the ICA. Both vertebral angiographies demonstrated a sudden diminution in caliber at the level of vertebrobasilar junction. There was an anomalous arterial collateral circulation originating from vertebral muscular and meningeal branch. There was also an absence of the basilar artery (BA).

CONCLUSION

This is the first case with CRM associated with bilateral segmental ICA and BA absence. The cause of this bilateral segmental ICA and BA absence may be maldevelopment of vessel connective tissue or extracellular matrix.

"Duplicated" or "multiple" cervical internal carotid and vertebral arteries from fenestration, duplication and vasa vasorum to segmental rete

SUMMARY

The appearance of multiple cervical arteries may be due to a variety of anatomic situations. Arterial fenestrations and duplications have different anatomic origins, with distinct appearances on angiography. They are associated with incomplete segmental development. The vasa vasorum of the internal carotid artery are rarely seen unless enlarged in pathological situations. They represent a peculiar segmental, in-situ, collateral circulation. Retes, on the other hand, correspond to a more complex reconstitution of an early segmental regression. Careful analysis of each of these features is required to choose the best appropriate terminology. The purpose of this paper is to report illustrative cases to enhance the distinctive features of each disposition.