Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography.

PURPOSE: To describe a case of multiple extremely rare cervical arterial variations. METHODS: A 55-year-old man with a tentative diagnosis of right internal carotid artery (ICA) stenosis was examined using computed tomography (CT) angiography for the evaluation of vascular lesions in the neck and head region. A 64-slice CT machine was used. RESULTS: On CT angiography, there was laterally located and narrowed petrous segment of the right ICA, indicative of aberrant course of the petrous ICA. Right vertebral artery (VA) was small in caliber and a relatively large anomalous artery arose from the proximal right ICA. This anomalous artery entered the posterior fossa via the foramen magnum, indicative of a type 1 proatlantal artery. Right occipital artery (OA) arose from the proximal ICA. The left OA also arose from the proximal ICA. CONCLUSION: An aberrant course of the petrous ICA is an extremely rare arterial variation which is formed by segmental agenesis of the cervical ICA, and the collateral channel passes through the middle ear cavity. It can be dangerous during middle ear surgery. The type 1 proatlantal artery is also an extremely rare arterial variation formed by the persistence of the proatlantal intersegmental artery. It is clinically significant because of its unique blood flow from the carotid system to the vertebrobasilar system. The OA rarely arises from the proximal ICA. Identification of these cervical arterial variations before surgery and vascular intervention are important to avoid complications during the procedure.

Interventions and imaging in patients with anatomic variations of cerebral circulation: a pictorial review.

The cerebral arterial system shows a wide spectrum of variations. Minor degrees of anatomic differences can be seen in almost all patients. Recognition of these anatomic variants is essential for the following: evaluating collateral circulation; some anatomic variants may mimic pathology; increased risk for aneurysm formation with some variants (e.g. fenestration, persistent trigeminal artery); dealing with pathologies that can arise with these variations; and for preoperative planning. The anterior and posterior groups of intracranial circulation show numerous anastomoses that play a major role in maintaining adequate blood supply to the cerebral parenchyma. This review focuses on the imaging features of these variants as seen on computed tomography and magnetic resonance imaging with relevant digital subtraction angiography imaging. We also present some case illustrations where understanding of these variants contributed to providing appropriate management.

Aberrant course of the petrous internal carotid artery associated with ipsilateral type 1 proatlantal artery.

PURPOSE: To describe an extremely rare case of an aberrant course of the petrous internal carotid artery (ICA) associated with an ipsilateral type 1 proatlantal artery (PA) that was diagnosed by cerebral magnetic resonance (MR) angiography. CASE REPORT: The patient was a 64-year-old man with double vision. Cerebral MR imaging and MR angiography were subsequently performed using a 1.5-T scanner. MR angiography showed an aberrant course of the petrous right ICA that was associated with right type 1 PA. The left vertebral artery (VA) and proximal right VA were absent. DISCUSSION: An aberrant course of the petrous ICA is rare but clinically significant, because it is dangerous during middle ear surgery. Type 1 PA is an extremely rare type of persistent fetal anastomosis between the carotid and vertebrobasilar systems. Type 1 PA is also clinically significant, because it is dangerous during craniovertebral junction surgery. We found no similar cases in the relevant English-language literature. CONCLUSION: Although both variations were seen ipsilaterally and were located relatively close to each other, the embryological development of these variations is quite different. In addition, no similar case has been reported previously. Thus, these may have formed incidentally.

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.

Aberrant right subclavian artery with right type 1 proatlantal artery and segmental dysplasia of the right internal carotid artery: a case report.

PURPOSE: We present a case of an aberrant right subclavian artery (ARSA) with extremely rare vascular anomalies. CASE REPORT: A 69-year-old woman was suspected to have right internal carotid artery (ICA) stenosis. Computed tomography angiography demonstrated an ARSA and hypoplasia of the right ICA. The proximal segment of the right vertebral artery (VA) was aplasia, and a right type 1 proatlantal artery (PA) arose from the right common carotid artery. Cerebral angiography demonstrated segmental dysplasia of the right ICA. The ascending intrapetrous segment and the ascending foramen lacerum-horizontal intracavernous segment of the right ICA demonstrated hypoplasia. The collateral pathways promoted reconstitution of each of the distal segments. Left internal carotid angiography demonstrated anterior communicating artery aneurysm and sufficient cross flow to the contralateral middle cerebral artery via the AcomA. DISCUSSION: A type 1 PA with an ARSA may result in the regression of the right dorsal aorta with persistence of the first cervical intersegmental artery. Although there are few findings of a relationship between an ARSA and intracranial artery anomalies, a developmental error of the right dorsal aorta may cause such complex vascular anomalies. CONCLUSION: Knowledge of anatomical variations in patients with ARSA is useful when performing angiography or endovascular therapy, as well as during clinical follow-up.

Anomalous anastomosis between the external carotid artery and vertebrobasilar artery via the hypoglossal canal: a case report and review of literature.

We report a case of an anomalous anastomosis formed between the external carotid artery (ECA) and the vertebrobasilar artery (VBA) and passing through the hypoglossal canal. A carotid-vertebrobasilar anastomosis of this kind is typically considered a variant of persistent primitive hypoglossal artery which usually originates from the internal carotid artery. However, the anastomotic vessel in this case had a common trunk with the occipital artery (OA), a remnant of the primitive proatlantal artery. The proximal and distal parts of the anastomotic vessel seemed to have been derived from the primitive proatlantal artery and the primitive hypoglossal artery, respectively. Thus, we propose that this ECA-VBA anastomosis, which passed through the hypoglossal canal and had a common trunk with the OA, be referred to as a dilated primitive hypoglossal-proatlantal anastomosis; that is, a dilated ascending pharyngeal artery rather than a variant of persistent primitive hypoglossal artery.

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.

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.

Bilateral concurrent type I and type II persistent proatlantal arteries: A case report.

Transient embryonic carotid-vertebrobasilar anastomoses can intermittently persist beyond the embryonic period. These vascular anomalies are often serendipitously identified during evaluation for unrelated disease states and pathologies. The persistent proatlantal intersegmental artery is one such recognized rare fetal anastomotic connection, often arising unilaterally. Bilateral persistence of the proatlantal anastomosis is a rarer occurrence, seldom described in the literature. We report a case of bilateral concurrent type I and type II proatlantal arteries, describe the embryology of persistent carotid-vertebrobasilar anastomoses, and consider pertinent clinical implications.

Treatment of a posterior cerebral artery aneurysm in the context of complex cardio-cerebrovascular variations using the Tubridge flow diverter.

We present a case of intracranial aneurysm located in the P1 segment of left posterior cerebral artery in the context of tetralogy of Fallot. Complex variations included right aortic arch with abnormal branching. Also, the bilateral vertebral arteries were absent, with a type I persistent proatlantal intersegmental artery of the left side. The aneurysm was treated with endovascular intervention with a Tubridge flow diverter and was noted to be completely cured on 6-month follow-up. We discuss the many considerations in this patient including developmental and modern-era treatment.

Mechanical Thrombectomy for Basilar Artery Occlusion with a Type 1 Persistent Proatlantal Artery: A Case Report and Literature Review.

Objective: Persistent proatlantal artery (PPA) is a primitive carotid-vertebrobasilar anastomosis (CVA); acute ischemic stroke due to basilar artery (BA) occlusion via a PPA is extremely rare. Case Presentation: An 84-year-old female developed disturbance of consciousness (Glasgow Coma Scale E2V1M5) and quadriparesis with a National Institutes of Health Stroke Scale score of 35. Head CT revealed early ischemic changes in the right temporal lobe, and a hyperdense vessel sign in the BA. Cerebral angiography showed that the left vertebral artery (VA) did not originate from the left subclavian artery or aortic arch. A left common carotid artery angiogram showed the presence of the left PPA originating from the left external carotid artery. Mechanical thrombectomy (MT) with contact aspiration using a Penumbra 5MAX ACE 60 aspiration catheter was performed, and successful recanalization was achieved after clot retrieval in the first attempt (thrombolysis in cerebral infarction scale 2b). MRI performed the following day, however, revealed a newly developed large hemorrhagic infarction in the pons, with no improvement in her symptoms (modified Rankin Scale score of 5 at 90 days). Conclusion: Although MT achieved successful recanalization of the BA via the PPA, her clinical symptoms did not improve, probably because of poor collateral circulation or the long length of the occlusion. In patients with acute vertebro-BA occlusion, if the VA does not originate from the subclavian artery or aortic arch, the presence of a primitive CVA should be considered.

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.

Endovascular Therapy for an Aneurysm of a Distal Posterior Inferior Cerebellar Artery via the Ipsilateral Persistent Primitive Proatlantal Artery: A Case Report.

Objective: We describe the rare case of a patient who was treated for a ruptured distal posterior inferior cerebellar artery (PICA) aneurysm via an ipsilateral persistent primitive proatlantal artery (PPPA). Case Presentation: An 86-year-old female with a medical history of hypertension presented with headache and nausea. CT showed subarachnoid hemorrhage in the posterior cranial fossa, and CTA revealed an aneurysm at the left-side distal PICA. In the left-sided common carotid angiography, the artery with a branch of the occipital artery from the external carotid artery was described. This artery continued as the V3 segment and entered the dura via the foramen magnum. The artery perfused the territory of the left vertebral artery and PICA. We concluded that the artery, which entered the dura, was a PPPA. We decided to perform endovascular therapy that passed through the PPPA. The aneurysm was located in the cortical segments, beyond the cranial loop. We decided that parent artery occlusion (PAO) would be more effective than selective coil embolization to achieve safe and adequate hemostasis. The patient had a good outcome with PAO not assessing collateral circulation. Conclusion: The emergency endovascular treatment with rare vascular variations requires accurate anatomical knowledge for treatment.

Segmental Agenesis of External Carotid Artery from Common Carotid Artery with Anomalous Reformation through Occipital Artery Anastomoses.

Anomalous origin of extracranial and intracranial carotid system is subject to permutations of embryonal regression of the developing primitive embryonal vasculature. We present a case of segmental agenesis of left external carotid artery from the cervical carotid circulation. The entire left external carotid artery was supplied by the vertebral artery through muscular branches via the occipital artery. This anomaly of proximal external carotid agenesis with the entire vascular tree dependent on the posterior circulation via occipital artery muscular collaterals is unique and has not been described before. We discuss this anomaly with its embryology, clinical implications, and its relationship to a Proatlantal artery.

Stent-assisted coil embolization for an unruptured vertebral artery-posterior inferior cerebellar artery aneurysm with retrograde access via type 1 persistent primitive proatlantal artery: A case report.

Vertebral artery (VA)-posterior inferior cerebellar artery (PICA) aneurysms are rare lesions that are difficult to treat with both endovascular and surgical techniques. Tight angulation of the PICA from VA may make access to the PICA difficult from ipsilateral VA if adjunctive techniques are needed. Recently, the safety and efficacy of retrograde access have been reported. We report a case of endovascular treatment for a VA-PICA aneurysm with a stent-assisted technique using retrograde access via contralateral persistent primitive proatlantal artery (PPA).The patient was a 76-year-old woman with an unruptured VA-PICA aneurysm on the dominant VA side. Coil embolization with a stent-assisted technique using retrograde access seemed appropriate. However, the origin of the left VA was not confirmed. Left common carotid artery angiography demonstrated that the PPA (type 1) branching from external carotid artery joined the VA V4 segment.Retrograde access via the PPA for stenting was performed. A microcatheter for stenting was retrogradely advanced to the right PICA at ease. After deploying the stent, coil insertion was completed from the right VA, and the final angiogram showed adequate occlusion of the aneurysm with preservation of the PICA.Thus, PPA may be an approach route in the treatment of VA-PICA aneurysms with unconfirmed contralateral VA orifice and apparent PPA on angiography, when retrograde access is needed.

Carotid-vertebrobasilar anastomosis: magnetic resonance and computed tomographic angiographic demonstration.

Carotid-vertebrobasilar (VB) anastomoses are rare and usually found incidentally, but they can have clinical significance. Their variance can represent aneurysm formation at the origin of the anomalous artery, cerebral ischemia due to unique blood flow, or other complications. Thus, recognition and correct diagnosis of these anomalous vessels are important when interpreting magnetic resonance (MR) and computed tomography (CT) angiography. This pictorial essay presents MR and CT angiographic images of several types of persistent fetal carotid-VB anastomoses, including those involving the proatlantal, hypoglossal, and trigeminal arteries as well as their variants. Images depict types 1 and 2 proatlantal arteries, persistent second cervical intersegmental artery, persistent hypoglossal artery (PHA), PHA of external carotid origin, two types of the PHA variant, posterior inferior cerebellar artery arising from the jugular branch of the ascending pharyngeal artery, lateral and medial types of persistent trigeminal arteries (PTAs), and four types of PTA variants.

A Type 1 Persistent Proatlantal Artery Originating from the External Carotid Artery Detected by Computed Tomographic Angiography.

A persistent proatlantal artery (PA) is rare. We report a type 1 persistent PA originating from the right external carotid artery (ECA). A 78-year-old woman presented with dizziness. Computed tomographic (CT) angiography showed a persistent PA originating from the right ECA. This persistent PA did not pass through the atlas transverse foramen. The extracranial segment of this artery in the atlas transverse process level had a more lateral position than a normal left vertebral artery. CT angiography well demonstrated the relationship with bony structures and the course of this persistent PA. This anomalous artery in our patient presented as an incidental finding. Surgeon should recognize a persistent PA when performing carotid endarterectomy or ligation of the ECA for avoidance of complication.

Basilar vascular system supplied by only right proatlantal intersegmentary artery type 1 with aneurysm and left internal carotid occlusion: a case report and review from the literature.

Persistence of proatlantal artery (PA) is a rare condition. More than 40 cases were described in the literature. Aneurysm may involve the PA itself in approximately 2% of cases, most arising from the internal carotid artery (ICA) side of PA. This case was particular because the PA showed a saccular aneurysm on the posterior wall, probably due to atherosclerosis disease and other alterations: plaque ulcerative of ICA, occlusion of left ICA, and aberrant right VA.