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

A large vertebral artery fenestration involving the distal segments associated with bilateral duplication of the superior cerebellar artery: a case report

PURPOSE

The aim of our study is to report a case of a large fenestrated vertebral artery (FVA) and bilateral duplication of the superior cerebellar artery (SCA) incidentally diagnosed using Computed Tomography Angiography (CTA) and Digital Subtraction Angiography (DSA).

CASE PRESENTATION

A 63-year-old female patient presenting to the neurology clinic with complaints of dizziness and balance disorder. CTA and DSA revealed a large FVA involving the V3 and V4 segments. Additionally, we observed bilateral duplicated SCAs originating from the distal basilar artery.

DISCUSSION

FVA is a rare anomaly resulting from fusion failure during the embryological period, with a reported incidence of 0.1%. FVA is often (70%) detected in the extracranial region, but it can also occur intracranially at a frequency of approximately 30%. Although various nomenclatures are used in the literature, we identified only two reports of a single fenestration encompassing the V3 and V4 segments, i.e., involving both the extracranial and intracranial regions. While duplication of the SCA is relatively common, bilateral duplication of SCA occurs at a rate of 0.9-5%.

CONCLUSION

This case report describes an unusual case of VA fenestration involving both extracranial and intracranial segments, along with bilateral duplication of the SCAs. While rare, these findings highlight the importance of recognizing such vascular anomalies, which could be relevant for planning surgical or endovascular procedures in the posterior circulation.

Bilateral internal carotid artery agenesis coexisting with bovine aortic arch: case report and literature review

This case study aims to elucidate the rare occurrence of bilateral internal carotid artery agenesis combined with a bovine aortic arch. The main objectives are to explore the incidence, embryological origins, clinical manifestations, and associated anomalies of this unique vascular condition. The study involves a detailed investigation of a 55-year-old male with a history of recurrent transient ischemic attacks (TIAs) using MRI and CT scan. The patient's medical history, clinical examination, and imaging results were systematically analyzed to provide a thorough understanding of the anatomical variations. The main findings include the rare coexistence of bilateral ICA agenesis and a bovine aortic arch, making this the 39th documented occurrence of bilateral ICA agenesis and the first recorded instance of its association with a bovine aortic arch. Also, the study highlighted the demographic characteristics, clinical presentations, and associated anomalies observed in the 38 documented cases of bilateral internal carotid artery agenesis. This case report contributes valuable insights into the rarity of bilateral internal carotid artery agenesis and its unprecedented association with a bovine aortic arch. The findings emphasize the importance of heightened anatomical awareness in clinical practice, particularly. Recognizing and understanding such variations is crucial for accurate diagnosis, appropriate management, and improved patient outcomes. Further research in this area is warranted to deepen our understanding of these complex vascular anomalies.

Rare neurovascular variants that you probably have not seen before

BACKGROUND

Recognition of neurovascular variants is crucial for safe endovascular and neurosurgical interventions. We aim to review and highlight various uncommon neurovascular variants and anomalies with a discussion of their relevant embryology and pathology.

METHODS

A retrospective review of a prospectively maintained neurovascular database was performed to identify uncommon neurovascular variants and anomalies. A pictorial review of these neurovascular findings is provided along with relevant embryological development, clinical significance, and potential pathological associations.

RESULTS

A pictorial review of selected neurovascular variants and anomalies is presented. These entities, divided between intra- and extra-cranial findings, include infra-optic origin of the anterior cerebral artery, meningo-ophtalmic artery, duplicated posterior cerebral artery, duplicate middle cerebral artery (MCA), MCA fenestration, twig-like MCA, pure arterial malformation, corkscrew basilar artery, persistent hypoglossal artery, persistent trigeminal artery and its variants, direct branches from the common carotid and cervical internal carotid arteries (ICA) (ascending pharyngeal artery from the ICA, thyroidal arteries from the CCA/brachiocephalic, arteria thyroidea ima), and extra-cranial carotid fenestration. The angiographic findings of these entities are presented with relevant 3D reconstruction and multimodal cross-sectional imaging correlation when available.

CONCLUSIONS

This pictorial review highlights uncommon neurovascular variants and anomalies that neuroradiologists, interventionalists, and neurosurgeons should be aware of for accurate diagnosis and safe interventions.

Correlation between Circle of Willis configuration and intracranial arterial dolichoectasia, and genetic contributions

OBJECTIVES

Intracranial arterial dolichoectasia (IADE) is characterized by the dilation, elongation, and tortuosity of intracranial arteries. We aimed to investigate the association between variations of the Circle of Willis (COW) and IADE in the general population, as well as estimate the genetic correlation between COW variations and IADE.

METHODS

A total of 981 individuals from a population-based cohort were included. Brain magnetic resonance angiography was performed to assess COW variants and measure the diameters of intracranial arteries. IADE was defined as a total intracranial volume-adjusted diameter ≥ 2 standard deviations. Logistic regression models were used to analyze the association between COW variations and IADE. The heritability and genetic correlation were estimated using genome-wide complex trait analysis (GCTA) based on single nucleotide polymorphism (SNP) array data.

RESULTS

The prevalence of IADE was 6.2 %. Hypoplastic/absent A1 segments were associated with an increase in contralateral ICA diameter (β ± SE, 0.279 ± 0.049; p = 0.001) and a decrease in ipsilateral ICA diameter (β ± SE, -0.300 ± 0.050; p = 0.001). Fetal-type posterior cerebral artery (FTP) was associated with a larger ICA diameter (β ± SE, 0.326 ± 0.048; p = 0.001) and a smaller BA diameter (β ± SE, -0.662 ± 0.043; p = 0.001). FTP revealed a positive genetic correlation with ICA dilation (rG = 0.259 ± 0.175; p = 0.0009) and a negative genetic correlation with BA dilation (rG = -0.192 ± 0.153, p = 0.015).

CONCLUSIONS

There was an association between COW variations and larger intracranial arterial diameters in the general population. Genetic factors may play a role in the development of intracranial arterial dilation and the formation of COW variants.

Fenestration of the anterior and posterior cerebral arteries in coexistence with a contralateral posterior cerebral artery of fetal origin

PURPOSE

The present case report aims to describe the rare coexistence of three variants of the cerebral arterial system diagnosed by computed tomography angiography (CTA).

METHODS

A retrospective study on head and neck CTAs was performed on a Greek adult population from the Department of Radiology, University Hospital of Larissa. An interesting case of an 80-year-old male was further investigated.

RESULTS

The cerebral arterial circle presented with a combination of three variations. The left anterior cerebral artery (ACA) was fenestrated 1.4 mm proximally to the anterior communicating artery formation. The left posterior cerebral artery (PCA) was also fenestrated, 5.5 mm distally to its origin from the basilar artery. Lastly, the right PCA originated from the ICA supraclinoid segment.

CONCLUSIONS

This case report highlights an unusual coexistence of A1 and P1 segments fenestration with a fetal PCA, resulting in a unique cerebral circle. A1 segment fenestration has been previously reported as rare, while the PCA fenestration as extremely rare variant. Awareness of these rare variations could aid interventionists in their preoperative assessments.

Rare simultaneous fetal posterior cerebral artery and conventional posterior cerebral artery duplication in a patient with a ruptured posterior communicating artery aneurysm: illustrative case

BACKGROUND

The fetal-type posterior cerebral artery (PCA) is defined as a variant anatomy in which the posterior communicating artery (PCOM) is larger than the hypoplastic or aplastic P1 segment of the PCA. The authors present the novel case of a patient with a duplicated right PCA in parallel with fetal-type and conventional PCAs supplying adjacent components of the PCA cerebral territory.

OBSERVATIONS

A 59-year-old woman presented with a modified Fisher Scale score 4 subarachnoid hemorrhage. A right irregular PCOM aneurysm that measured 9.5 mm × 4.5 mm × 4.5 mm arose from the base of a variant branch supplying a portion of the PCA, rather than a conventional PCOM, and was found on digital subtraction angiography. Following endovascular coil embolization, the patient was discharged home.

LESSONS

The fetal-type variant has implications for thromboembolic events. If an embolism occludes the anterior circulation in a patient with a fetal-type PCA, it may result in an infarct in the PCA territory. Awareness of cerebral arterial anatomy, including an atypical collateral supply, informs a treating team's latitude in tolerance of which sites must be preserved and which can be safely sacrificed. https://thejns.org/doi/10.3171/CASE23735.

Hemodynamics regulate spatiotemporal artery muscularization in the developing circle of Willis

Vascular smooth muscle cells (VSMCs) envelop vertebrate brain arteries and play a crucial role in regulating cerebral blood flow and neurovascular coupling. The dedifferentiation of VSMCs is implicated in cerebrovascular disease and neurodegeneration. Despite its importance, the process of VSMC differentiation on brain arteries during development remains inadequately characterized. Understanding this process could aid in reprogramming and regenerating dedifferentiated VSMCs in cerebrovascular diseases. In this study, we investigated VSMC differentiation on zebrafish circle of Willis (CoW), comprising major arteries that supply blood to the vertebrate brain. We observed that arterial specification of CoW endothelial cells (ECs) occurs after their migration from cranial venous plexus to form CoW arteries. Subsequently, acta2+ VSMCs differentiate from pdgfrb+ mural cell progenitors after they were recruited to CoW arteries. The progression of VSMC differentiation exhibits a spatiotemporal pattern, advancing from anterior to posterior CoW arteries. Analysis of blood flow suggests that earlier VSMC differentiation in anterior CoW arteries correlates with higher red blood cell velocity and wall shear stress. Furthermore, pulsatile flow induces differentiation of human brain PDGFRB+ mural cells into VSMCs, and blood flow is required for VSMC differentiation on zebrafish CoW arteries. Consistently, flow-responsive transcription factor klf2a is activated in ECs of CoW arteries prior to VSMC differentiation, and klf2a knockdown delays VSMC differentiation on anterior CoW arteries. In summary, our findings highlight blood flow activation of endothelial klf2a as a mechanism regulating initial VSMC differentiation on vertebrate brain arteries.

A primer to vascular anatomy of the brain: an overview on anterior compartment

PURPOSE

Knowledge of neurovascular anatomy is vital for neurosurgeons, neurologists, neuro-radiologists and anatomy students, amongst others, to fully comprehend the brain's anatomy with utmost depth. This paper aims to enhance the foundational knowledge of novice physicians in this area.

METHOD

A comprehensive literature review was carried out by searching the PubMed and Google Scholar databases using primary keywords related to brain vasculature, without date restrictions. The identified literature was meticulously examined and scrutinized. In the process of screening pertinent papers, further articles and book chapters were obtained through analysis and additional assessing of the reference lists. Additionally, four formalin-fixed, color latex-injected cadaveric specimens preserved in 70% ethanol solution were dissected under surgical microscope (Leica Microsystems Inc, 1700 Leider Ln, Buffalo Grove, IL 60089 USA). Using microneurosurgical as well as standard instruments, and a high-speed surgical drill (Stryker Instruments 1941 Stryker Way Portage, MI 49002 USA). Ulterior anatomical dissection was documented in microscopic images.

RESULTS

Encephalic circulation functions as a complex network of intertwined vessels. The Internal Carotid Arteries (ICAs) and the Vertebral Arteries (VAs), form the anterior and posterior arterial circulations, respectively. This work provides a detailed exploration of the neurovascular anatomy of the anterior circulation and its key structures, such as the Anterior Cerebral Artery (ACA) and the Middle Cerebral Artery (MCA). Embryology is also briefly covered, offering insights into the early development of the vascular structures of the central nervous system. Cerebral venous system was detailed, highlighting the major veins and tributaries involved in the drainage of blood from the intracranial compartment, with a focus on the role of the Internal Jugular Veins (IJVs) as the primary, although not exclusive, deoxygenated blood outflow pathway.

CONCLUSION

This work serves as initial guide, providing essential knowledge on neurovascular anatomy, hoping to reduce the initial impact when tackling the subject, albeit the intricate vasculature of the brain will necessitate further efforts to be conquered, that being crucial for neurosurgical and neurology related practice and clinical decision-making.

Pathology-based brain arterial disease phenotypes and their radiographic correlates

INTRODUCTION

Brain arterial diseases, including atherosclerosis, vasculitis, and dissections, are major contributors to cerebrovascular morbidity and mortality worldwide. These diseases not only increase the risk of stroke but also play a significant role in neurodegeneration and dementia. Clear and unambiguous terminology and classification of brain arterial disease phenotypes is crucial for research and clinical practice.

MATERIAL AND METHODS

This review aims to summarize and harmonize the terminology used for brain large and small arterial phenotypes based on pathology studies and relate them to imaging phenotypes used in medical research and clinical practice.

CONCLUSIONS AND RESULTS

Arteriosclerosis refers to hardening of the arteries but does not specify the underlying etiology. Specific terms such as atherosclerosis, calcification, or non-atherosclerotic fibroplasia are preferred. Atherosclerosis is defined pathologically by an atheroma. Other brain arterial pathologies occur and should be distinguished from atherosclerosis given therapeutic implications. On brain imaging, intracranial arterial luminal stenosis is usually attributed to atherosclerosis in the presence of atherosclerotic risk factors but advanced high-resolution arterial wall imaging has the potential to more accurately identify the underlying pathology. Regarding small vessel disease, arteriosclerosis is ambiguous and arteriolosclerosis is often used to denote the involvement of arterioles rather than arteries. Lipohyalinosis is sometimes used synonymously with arteriolosclerosis, but less accurately describes this common small vessel thickening which uncommonly shows lipid. Specific measures of small vessel wall thickness, the relationship to the lumen as well as changes in the layer composition might convey objective, measurable data regarding the status of brain small vessels.

Posterior vascular anatomy of the encephalon: a comprehensive review

PURPOSE

This article presents a comprehensive exploration of neurovascular anatomy of the encephalon, focusing specifically on the intricate network within the posterior circulation and the posterior fossa anatomy; enhancing understanding of its dynamics, essential for practitioners in neurosurgery and neurology areas.

METHOD

A profound literature review was conducted by searching the PubMed and Google Scholar databases using main keywords related to neurovascular anatomy. The selected literature was meticulously scrutinized. Throughout the screening of pertinent papers, further articles or book chapters were obtained through additional assessment of the reference lists. Furthermore, four formalin-fixed, color latex-injected cadaveric specimens preserved in 70% ethanol solution were dissected under surgical microscope (Leica Microsystems Inc, 1700 Leider Ln, Buffalo Grove, IL 60089, USA), using microneurosurgical as well as standard instruments, and a high-speed surgical drill (Stryker Instruments 1941 Stryker Way Portage, MI 49002, USA). Ulterior anatomical dissection was performed.

RESULTS

Detailed examination of the basilar artery (BA), a common trunk formed by the union of the left and right vertebral arteries, denoted a tortuous course across the basilar sulcus. Emphasis is then placed on the Posterior Inferior Cerebellar Artery (PICA), Anterior Inferior Cerebellar Artery (AICA) and Superior Cerebellar Artery (SCA). Each artery's complex course through the posterior fossa, its divisions, and potential stroke-related syndromes are explored in detail. The Posterior Cerebral Artery (PCA) is subsequently unveiled. The posterior fossa venous system is explained, categorizing its channels. A retrograde exploration traces the venous drainage back to the internal jugular vein, unraveling its pathways.

CONCLUSION

This work serves as a succinct yet comprehensive guide, offering fundamental insights into neurovascular anatomy within the encephalon's posterior circulation. Intended for both novice physicians and seasoned neuroanatomists, the article aims to facilitate a more efficient clinical decision-making in neurosurgical and neurological practices.

A comprehensive review of the vertebral artery anatomy

BACKGROUND

The vertebral arteries (VA) play a critical role by supplying nearly one-third of the brain's blood flow, predominantly contributing to the posterior circulation. These arteries may need to be exposed in a various cranial and cervical procedures and offers access to investigate or treat vascular lesions by endovascular means related to the posterior circulation. Given its complex anatomy, which is subject to numerous variations, and its role in supplying vital brain regions, a thorough understanding of the VA's anatomy is paramount for any related procedure.

OBJECTIVE

To provide a comprehensive overview of vertebral artery anatomy and its relevance in contemporary clinical practice.

METHODS

Dissection of the entire vertebral artery length using cadaveric specimen, combined with a comprehensive literature review.

RESULTS

The vertebral artery can be subdivided into four segments. Each of these segments has its own unique topographic anatomy with its variations, anastomoses, and significance in surgery.

CONCLUSION

As surgical and endovascular techniques continue to evolve with technological improvements, we are now more equipped than ever to manage complex lesions involving the VA. However, with its increasingly complexity comes the necessity for a deeper and more comprehensive understanding of the VA. Possessing the detailed knowledge of the VA is vital for the successful execution of any procedure involving it.

Long-term clinical and radiological trajectories of craniocervical vasculopathy in children with PHACE syndrome

AIM

To describe the rates of stroke and craniocervical vasculopathy progression in children with posterior fossa malformations, hemangioma, arterial anomalies, coarctation of the aorta/cardiac defects, and eye abnormalities (PHACE) syndrome.

METHOD

A single-center, retrospective natural history study of children with PHACE syndrome. Clinical and sequential neuroimaging data were reviewed to study the characteristics and progression of vasculopathy and calculate the rates of arterial ischemic stroke (AIS) and transient ischemic stroke (TIA). Vasculopathy progression was defined as worsening or new vascular findings on follow-up magnetic resonance angiography.

RESULTS

Thirty-four children with cerebrovascular abnormalities at the PHACE syndrome diagnosis were studied (age range = 2 to 18 years, 85% females). Median age at the initial diagnosis was 5.5 months (interquartile range = 1-52 months); median age at the last follow-up was 8 years 6 months (range = 2-18 years). Overall, 10 (29%) patients had radiological progression of their vasculopathy, with a cumulative progression-free rate of 73% (95% confidence interval [CI] = 0.57-0.89), and a cumulative TIA-free and AIS-free rate of 87% (95% CI = 0.745-0.99). Vasculopathy was continuously progressive in six patients (18%) at the last follow-up. Three patients (9%) had TIA and all had progressive vasculopathy. One patient had presumed perinatal AIS at the initial PHACE diagnosis, while no other patient experienced an AIS during the follow-up.

INTERPRETATION

In children with PHACE syndrome, craniocervical vasculopathy is non-progressive and asymptomatic in the majority of cases. The risk of ischemic stroke in these children is very low. Larger and prospective studies are necessary to confirm these findings.

Development of Collateral Vessels after Anterior Circulation Large Vessel Occlusion in Pediatric Arterial Ischemic Stroke Relates to Stroke Etiology: A Longitudinal Study

BACKGROUND AND PURPOSE

The characteristics of large vessel occlusion (LVO) in the acute phase of pediatric arterial ischemic stroke and their natural history according to stroke etiology are poorly explored. This studied aimed at describing the prevalence and the radiological evolution of LVO in pediatric AIS.

MATERIALS AND METHODS

This single-center retrospective study included consecutive non-neonate children with acute arterial ischemic stroke, intracranial proximal LVO in the anterior circulation (MCA, anterior cerebral artery, and/or ICA), and clinical and imaging follow-up for at least 18 months, during a 9-year period.

RESULTS

Intracranial LVO was observed in 24.8% of patients with anterior circulation arterial ischemic stroke and adequate follow-up (n = 26/105), with a median age of 4.2 years (IQR 0.8-9), sex ratio 1.16. The main stroke etiology associated with LVO was unilateral focal cerebral arteriopathy (n = 12, 46%). During follow-up, a specific pattern of unilateral poststroke anastomotic bridge was observed in 8/26 patients, with the poststroke development of nonperforating collaterals forming a bridge in bypass of the LVO site with visible distal flow, within a median delay of 11 months. The development of unilateral poststroke anastomotic bridge was only observed in patients with unilateral focal cerebral arteriopathy. No patient with this pattern experienced stroke recurrence or further progressive vascular modifications.

CONCLUSIONS

After stroke, the development of unilateral poststroke anastomotic bridge is specifically observed in children with focal cerebral arteriopathy, appearing in the first year after stroke. This clinical-radiologic pattern was not associated with stroke recurrence or arterial worsening, differentiating it from progressive intracranial arteriopathy, such as Moyamoya angiopathy.

The Vertebrobasilar Trunk and Its Anatomical Variants: A Microsurgical Anatomical Study

BACKGROUND

The trunk of the basilar artery has not been included in microanatomy studies. Anatomical variants of the perforant branches of the vertebrobasilar trunk and their relationship with neural structures are very important in surgical approaches. Surgical dissection for the treatment of vascular lesions requires a perfect knowledge of the microsurgical anatomy.

METHODS

We conducted a descriptive analysis of 50 brains, which were fixed with formalin at 10% for 2 weeks, and the arterial system was injected with colored latex. After microsurgical dissection, it was divided into three segments: the lower portion went from the anterior spinal artery to the anteroinferior cerebellar artery, the middle segment was raised from the upper limit of the lower portion to the origin of the superior cerebellar artery, and the upper segment ranged from the previous portion until the origin of the posterior cerebral artery.

RESULTS

The basilar artery had an average length of 30 mm. The average diameter at its junction with the vertebral arteries was 4.05 mm. The average middle segment was 3.4 mm in diameter and 15.2 mm in length. The diameter of the upper segment was 4.2 mm, and its average length was 3.6 mm. The average number of bulbar arteries was three, and their average diameter was 0. 66 mm. The number of caudal perforator arteries were five on average, with a diameter of 0.32 mm. We found three rare cases of anatomical variants in the vertebra-basilar junction.

CONCLUSIONS

The basilar artery emits penetrating branches in its lower, middle, and upper portions. The origin of penetrating branches was single or divided after forming a trunk. However, we observed long branches from perforant arteries.

Trend of cerebral aneurysms over the past two centuries: need for early screening

OBJECTIVE

Cerebral aneurysms (CAs) are linked to variations in the cerebral basal arterial network (CBAN). This study aimed to find the optimal age for screening to detect brain arterial variations and predict aneurysms before rupture.

DESIGN

An observational, quantitative and retrospective research.

SETTING

The study analysed 1127 cases of CAs published from 1761 to 1938. Additionally, CT angiography images of 173-patients at the Royal Adelaide Hospital (RAH), South Australia between 2011 and 2019 were examined for the presence and the location of aneurysms in CBAN.

PARTICIPANTS

The data were collected from patients at RAH and 407 published sources, including males and females across the entire age range, up to 100 years old.

OUTCOME MEASURES AND RESULTS

Data, CAs cases, from 1761 to 1938 included (526 males, 573 females and 28 unknown sexes). The age of these patients varied from 18 months to 89 years (mean age=42, SD=18). Approximately 11.5% of the CAs occurred in patients aged <20 years. Among the 1078 aneurysms whose location was reported, 76% were located in the internal carotid (IC), middle cerebral (MC) and anterior communicating artery complex (AcomAC) regions, while the remaining 24% were in the vertebrobasilar region. Among 173 patients from RAH aged between 18 and 100 years (male=83 and female=90, mean age=60, SD=16), 94% of the CAs were found in the IC, MC and AcomAC regions. The pattern of aneurysm occurrence, as indicated by values at the 25th, 50th and 75th percentiles, along with the minimum and maximum patient ages, has remained consistent from 1761 to 2019.

CONCLUSION

The distribution pattern of CAs in relation to sex, age and locations in the CBAN, remained steady over the last 260 years resulting in risk of strokes early in life. Therefore, early screening for CBAN segment variations is advised for stroke prevention if possible.

Stability of infundibular dilatations: a single center follow-up study and systematic review of the literature

PURPOSE

Although infundibular dilatations (IDs) have been thought to be benign anatomical variants, case reports suggest that they can grow and rupture. The aim of this study was to determine whether IDs have a tendency to grow or rupture.

METHODS

The study population was collected from the Tampere University Hospital (TAUH) Aneurysm Database. The presence of IDs was screened from the medical records and imaging studies of 356 intracranial aneurysm patients left to follow-up from 2005 to 2020. The imaging studies were reviewed to confirm the IDs, and their clinical course. Finally, we performed a systematic review of published cases of ID leading to aneurysmatic rupture from PubMed.

RESULTS

We found 97 typical IDs in 83 patients and 9 preaneurysmal lesions resembling ID in 9 patients. Out of the typical cone-shaped IDs, none grew or ruptured in a total follow-up of 409 patient-years. One preaneurysmal lesion ruptured during a follow-up: this lesion had components of both infundibular dilatation and aneurysm at the beginning of follow-up. In the systematic literature search, we found 20 cases of aneurysmatic SAHs originating from an ID. Of those, only 7 had imaging available prerupture. All 7 IDs were typically cone-shaped, but a branching vessel originating from the apex of ID was only seen in 4/7.

CONCLUSION

Typical infundibular dilatations seem to be benign anatomical variants that are stable and, thus, do not need prophylactic treatment or imaging follow-up. Likely, the SAHs reported from IDs were actually caused by misdiagnosed preaneurysmal lesions.

Adding a chapter to the literature: A rare encounter of unilateral Moyamoya disease with ipsilateral persistent trigeminal artery

Background

The coexistence of persistent trigeminal artery (PTA) and Moyamoya disease (MMD) has been reported. If their pathogenesis is related and if PTA is protective or harmful in MMD remains unknown as these are rare cerebrovascular anomalies.

Case presentation

A 35-year-old woman with sudden global aphasia whose CT head and CT angiography of head and neck showed a hypodensity in the left posterior middle cerebral artery (MCA), a possible left proximal internal carotid artery occlusion, and a left PTA with hypoplasia of vertebral and basilar arteries. Digital subtraction angiography showed chronic MMD in the left MCA with extensive pial collateralization from anterior cerebral artery (ACA). The patient was initiated on single antiplatelet therapy and later she underwent direct bypass surgical intervention and rehabilitation.

Discussion

Our case report brings attention to the infrequent coexistence of ipsilateral MMD and PTA suggesting a potential congenital pathogenesis based on embryologic development and hemodynamics. Also, we propose a protective role of PTA in MMD in case of large anterior vessel occlusion. This case contributes to the scarce literature on the intriguing relationship between MMD and PTA.

The role of fetal-type posterior cerebral artery in mediating occipital and thalamic perfusion: An arterial spin labeling MRI study

BACKGROUND

The posterior cerebral artery (PCA) is key in supplying blood to the occipital lobes and significant portions of the thalamus. Some individuals present with a 'fetal-type' posterior cerebral artery (fPCA), which is associated with a higher risk of neurological disorders such as ischemic stroke. This study investigates the relationship between the presence of fPCA and arterial spin labeling (ASL) hyperperfusion patterns in the medial occipital cortex and thalami.

METHODS

MRI scans from 84 patients with no detectable radiological evidence of brain pathology were retrospectively analyzed. We investigated the association between PCA type (normal vs. fetal) and perfusion pattern (hyperperfused vs. non-hyperperfused) using Fisher's exact test.

RESULTS

Hyperperfusion in the medial occipital cortex and thalami was absent in all patients with fPCA, but present in 69% of those with normal PCA. In patients with unilateral fPCA, hyperperfusion was exclusively observed on the side with the normal PCA.

CONCLUSION

The study suggests a consistent relationship between PCA type and ASL perfusion patterns in the medial occipital cortex and thalami. Further research is warranted to explore the physiological underpinnings of these findings and their potential clinical implications. Understanding this relationship could improve the interpretation of ASL MRI and contribute to a better understanding of pathophysiological mechanisms associated with PCA variants.

When Carotid Artery Stenosis Cause Posterior Fossa Infarct. An Unusual Case of Persistent Hypoglossal Artery

BACKGROUND

The primitive anastomosis between the carotid artery and the vertebrobasilar arteries usually regress, in rare cases they persist beyond fetal development and form vascular anomalies such as primitive persistent hypoglossal artery(PPHA), with prevalence of 0.02-0.1% in the general population.

CASE REPORT

A 77-year-old female presented with aphasia, weakness of both legs and arms. Computed Tomography Angiography (CTA) revealed subacute infarct in right pones, severe stenosis of the right internal carotid artery(RICA) and ipsilateral PPHA. We performed Right carotid artery stenting (CAS) using a distal filter into the PPHA to protect the posterior circulation, with good result.

DISCUSSION

The posterior circulation was utterly dependent on the RICA, therefore, despite the general notion that carotid stenosis is usually associated with anterior circulation infarcts, in cases having vascular anomalies it may cause a posterior stroke. Carotid artery stenting offer a safe and simple solution, however the use of EPD requires special considerations regarding decision on the suitable protection technique and placement.

CONCLUSION

Neurological symptoms in the presence of carotid artery stenosis and PPHA can manifest as ischemia of the anterior and/or the posterior circulation. In our opinion, CAS gives a simple and safe treatment solution.

Percutaneous transluminal angioplasty for persistent primitive hypoglossal artery stenosis: illustrative case

BACKGROUND

We report a case of symptomatic, progressive stenosis of a persistent primitive hypoglossal artery (PPHA), which was successfully treated with percutaneous transluminal angioplasty (PTA) of the origin of the PPHA. The PPHA is a type of carotid-basilar anastomosis with an incidence of 0.02% to 0.10%. It originates from the internal carotid artery (ICA), passes through the hypoglossal canal, and merges with the basilar artery. In many cases, the ipsilateral vertebral artery is hypoplastic; therefore, PPHA stenosis causes cerebral infarction in the posterior circulation territory, as in this case.

OBSERVATIONS

The patient's right PPHA had severe and progressive stenosis; therefore, he experienced cerebral infarction despite medical treatment. Therefore, PTA for the stenosis was performed, which ceased the recurrence of cerebral infarction and dizziness by improving blood flow in the posterior circulation.

LESSONS

Several reports have described ICA stenosis accompanied by PPHA or PPHA stenosis in patients receiving endovascular treatments. Almost all cases were nonprogressive, and the treatment procedure was stenting. However, in our case, the PPHA stenosis was progressive, and we performed PTA because the patient experienced resistance to antiplatelet drugs and had poor collateral flow.

Nomogram model for predicting the risk of post-stroke depression based on clinical characteristics and DNA methylation

Objective

To construct a comprehensive nomogram model for predicting the risk of post-stroke depression (PSD) by using clinical data that are easily collected in the early stages, and the level of DNA methylation, so as to help doctors and patients prevent the occurrence of PSD as soon as possible.

Methods

We continuously recruited 226 patients with a history of acute ischemic stroke and followed up for three months. Socio-demographic indicators, vascular-risk factors, and clinical data were collected at admission, and the outcome of depression was evaluated at the third month after stroke. At the same time, a DNA-methylation-related sequencing test was performed on the fasting peripheral blood of the hospitalized patients which was taken the morning after admission.

Results

A total of 206 samples were randomly divided into training dataset and validation set according to the ratio of 7:3. We screened 24 potentially-predictive factors by Univariate logistic regression and least absolute shrinkage and selection operator (LASSO) regression analysis, and 10 of the factors were found to have predictive ability in the training set. The PSD nomogram model was established based on seven significant variables in multivariate logistic regression. The consistency statistic (C-index) was as high as 0.937, and the area under curve (AUC) in the ROC analysis was 0.933. Replication analysis results in the validation set suggest the C-index was 0.953 and AUC was 0.926. This shows that the model has excellent calibration and differentiating abilities.

Conclusion

Gender, Rankin score, history of hyperlipidemia, time from onset to hospitalization, location of stroke, National Institutes of Health Stroke scale (NIHSS) score, and the methylation level of the cg02550950 site are all related to the occurrence of PSD. Using this information, we developed a prediction model based on methylation characteristics.

Aplastic Internal Carotid Artery: A Potentially Catastrophic Vascular Anomaly

Congenital absence of an internal carotid artery (ICA) is a rare vascular anomaly and occurs in less than 0.01% of the population. We report a case of aplastic internal carotid artery in a 34-year-old female. The patient presented to the emergency department with complaints of new-onset involuntary swaying-like movement of her right arm. Brain magnetic resonance imaging showed multifocal tiny areas of acute infarcts in the bilateral frontal, parietal, and left occipital lobes in the watershed distribution. There was no visualization of the flow of the intracranial left internal carotid artery. Follow-up CTA of the head and neck showed a congenital absence of the left internal carotid artery with no evidence of arterial dissection, occlusion, or aneurysm. Obstruction of the internal carotid artery has significant consequences for patients. This effect is amplified if the disruption occurs in the sole anterior blood supply to the parenchyma of the brain, as in this case. In our patient care, imaging was vital to the detection and subsequent treatment with anticoagulation to avoid further cerebral complications, and the patient will now have a better understanding of the increased lifetime risk of further events.

An Unusual Origin of the Left Vertebral Artery: A Case Report

The present paper describes a 53-year-old male who presented to the emergency department with a history of sudden chest pain followed by unconsciousness at home. The autopsy revealed the left vertebral artery (LVA)'s aberrant origin from the aortic arch between the left common carotid artery and subclavian artery in a male deceased during a medicolegal autopsy. The aortic origin of the vertebral artery is an unusual branching pattern. Knowledge about the vertebral artery's normal and variant arterial anatomy is essential for patients who undergo various surgical or interventional procedures. In the sudden death of cardiac origin, its anatomy and morphology also hold crucial value. Typically, the LVA arises from the first part of the left subclavian artery (LSA).

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.

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.

Stenting-assisted embolization of a saccular aneurysm of the azygos anterior cerebral artery associated with fenestration at its beginning

Aneurysms of the azygos anterior cerebral artery (AACA) associated with fenestration are exceptional. We reported such a case. A 61-year-old woman presented with subarachnoid hemorrhage. Computed tomography angiography and digital subtraction angiography showed an aneurysm at the distal end of the AACA with a fenestration at its beginning. Stenting-assisted coiling of the aneurysm was performed. The postoperative recovery was uneventful. Follow-up DSA showed complete coiling of the aneurysm. By this case report and review of the literature, we found that the coexistence of the aneurysm and fenestration on the AACA was exceptional. Endovascular treatment of saccular AACA aneurysms is an appealing option.

Congenital and acquired anomalies of the basilar artery: A pictorial essay

INTRODUCTION

The basilar artery is one of the two cases in our body where an arterial vessel is formed by the union of two others - the vertebral arteries. It provides vascular supply to essential structures for the main vital functions; the posterior cerebral arteries originate from it as terminal branches, and form part of the anastomotic circle of Willis.

IMAGING FINDINGS

Congenital and acquired anomalies of the basilar trunk are described. We provide a schematic and detailed representation of normal anatomical variants - mainly represented by the fenestrated basilar artery or the persistence of carotid-basilar anastomosis; course anomalies are also illustrated, with reference to neuro-vascular conflicts and dolichoectasia. Among congenital anomalies, this pictorial review also shows the variants of the basilar origin, such as in the case of basilar trunk arising from only one of the two vertebral arteries, and the calibre changes - which are represented by aneurysm and hypoplasia. The latter appears to be a risk factor for posterior circulation stroke, when associated with a bilateral posterior foetal variant.Among the acquired forms, this pictorial essay describes some clinical cases of dissections, non-congenital aneurysms, thrombosis and tumour with vascular encasing or compression of basilar artery.

CONCLUSION

CT angiography and MRI allow us to study the posterior intracranial circulation in detail, providing useful pre-treatment information. Therefore, knowledge of congenital or acquired anomalies of the basilar artery is essential for radiologists, neuroradiologists and neurosurgeons.

A Rare Case Report of a Vertebral Artery Variant Arising From the Aorta With Its Clinical Significance: An Uncommon Anatomy Unveiled

The vertebrobasilar (VB) system, comprising two vertebral arteries and one basilar artery, is responsible for providing vital vascular supply to the central nervous system structures. Disruption in this network can lead to fatal neurologic outcomes, and variations in the origin of vessels may contribute to unexplained symptoms of clinical relevance. Therefore, an extensive understanding of the VB system's anatomy and its variations is crucial for diagnosing neurological disorders. Here, we report a case of a vertebral artery variant arising from the aortic arch proximal to the left subclavian artery in the cadaver of a 50-year-old male, discovered incidentally during a teaching dissection session. We also discuss the clinical pathophysiology and the relevance of the neurological symptoms in relation to the anomaly.

Deep, spontaneous intracerebral hemorrhages: Clinical differences and risk factors associated with anterior versus posterior circulation

BACKGROUND

spontaneous intracerebral hemorrhages (ICH) in different anatomical locations are considered different clinical entities, associated with different vascular etiologies. However, such a distinction between deep ICH in the posterior vs. the anterior circulation is not well documented.

OBJECTIVE

to look for different demographic, clinical, laboratory and radiological variables in order to clarify any distinction between deep ICH of the posterior versus the anterior circulations.

MATERIAL AND METHODS

Retrospective study on patients diagnosed with deep, spontaneous ICH at a single tertiary center. Patients were divided into two groups: posterior circulation (group 1) and anterior circulation (group 2). Computerized medical records were extracted for multiple variables.

RESULTS

A total of 142 patients with deep ICH were included in the study; 54.9 % (n = 78) with posterior (group 1) and 45.1 % (n = 64) with anterior circulation hemorrhages (group 2). In group 1, 67.9 % (n = 53) of hemorrhages were in the cerebellum and 28.2 % (n = 22) in the thalamus. Patients in group 1 were older at time of hemorrhage (68.69 ± 11.66 vs. 64.95 ± 13.34, p = 0.073) and had nearly threefold increased rate of BMI≥ 35 (22.0 % vs. 8.6 %, p = 0.071). In multivariate analysis, use of anti-aggregates (OR=2.391; 95 % CI 1.082-5.285, p = 0.031) and past medical history of HTN (OR=2.904; 95 % CI 1.102-7.654, p = 0.031) were significantly associated with ICH of the posterior circulation. When excluding patients with thalamic hemorrhages, BMI ≥ 35 was also associated with significant risk of having a deep hemorrhage in the posterior circulation vs. the anterior circulation (OR=3.420; 95 % CI 1.011-11.574, p = 0.048). No significant differences were found between the two groups in terms of functional and survival outcomes.

CONCLUSION

HTN, use of anti-aggregates and morbid obesity are associated with deep ICHs of the posterior circulation and should be considered significant risk factors for this major clinical event. The growing data on pathophysiology of distinct subgroups of ICH will provide useful tools that will aid in preventing and treating these neurological emergencies. Future epidemiological and clinical studies should use the distinction between ICH subgroups based on their anatomical location and vascular territories as accurately as possible in order to reach solid conclusions.

Hippocampal Vascular Supply and Its Role in Vascular Cognitive Impairment

The incidence of age-related dementia is increasing as the world population ages and due to lack of effective treatments for dementia. Vascular contributions to cognitive impairment and dementia are increasing as the prevalence of pathologies associated with cerebrovascular disease rise, including chronic hypertension, diabetes, and ischemic stroke. The hippocampus is a bilateral deep brain structure that is central to learning, memory, and cognitive function and highly susceptible to hypoxic/ischemic injury. Compared with cortical brain regions such as the somatosensory cortex, less is known about the function of the hippocampal vasculature that is critical in maintaining neurocognitive health. This review focuses on the hippocampal vascular supply, presenting what is known about hippocampal hemodynamics and blood-brain barrier function during health and disease, and discusses evidence that supports its contribution to vascular cognitive impairment and dementia. Understanding vascular-mediated hippocampal injury that contributes to memory dysfunction during healthy aging and cerebrovascular disease is essential to develop effective treatments to slow cognitive decline. The hippocampus and its vasculature may represent one such therapeutic target to mitigate the dementia epidemic.

Novel Superior Cerebellar Artery Aneurysm Coming from a Superior Cerebellar Artery-Posterior Cerebral Artery Anastomotic Branch

A middle-aged patient presented with subarachnoid hemorrhage and was found to have a ruptured superior cerebellar artery (SCA) aneurysm arising from the origin of a rare anastomotic branch between the right SCA and right posterior cerebral artery (PCA). The aneurysm was secured by transradial coil embolization, and the patient made a good functional recovery. This case demonstrates an aneurysm arising from an anastomotic branch between the SCA and PCA, which may represent a remnant of a persistent primordial hindbrain channel. Although variations in basilar artery branches are common, aneurysms rarely can form at the site of seldom- seen anastomoses between the branches of the posterior circulation. The complex embryology of these vessels, which includes anastomoses and the involution of primitive arteries, may have contributed to the development of this aneurysm arising from an SCA-PCA anastomotic branch.

New variant of persistent primitive trigeminal artery associated with duplicated basilar artery: a radiological case report

PURPOSE

This article reports a new variant of the persistent primitive trigeminal artery. This variant does not exist in Salas and Saltzman classifications.

METHODS

We analyzed CTA images of a 39-year-old male patient using RadiAnt. This work had clinical and research purposes.

RESULTS

A persistent primitive trigeminal artery arose from left internal carotid artery termination. Its course was atypical, superior, and lateral to the sella turcica. At its end, it joined a duplicated basilar artery. These morphological features are new compared to Salas and Saltzman's variants.

CONCLUSION

Anatomists, radiologists, and neurosurgeons must know this new variant. Angiographic analysis of this variant will keep the patient safe and perform the surgery. This new variant deserves to be considered in Salas and Saltzman classifications as a new type.

A challenging case of recurrent and progressive fusiform anterior circulation intracranial aneurysms: illustrative case

BACKGROUND

Intracranial fusiform aneurysms are circumferential dilations of cerebral arteries that can lead to complications including ischemic stroke due to vessel occlusion, subarachnoid hemorrhage, or intracerebral hemorrhage. Treatment options for fusiform aneurysms have expanded significantly in recent years. Microsurgical treatment options include proximal and distal surgical occlusion and microsurgical trapping of the aneurysm, usually in association with high-flow bypass procedures. Endovascular treatment options include the placement of coils and/or flow diverters.

OBSERVATIONS

Here the authors report a case of aggressive surveillance and treatment of a man with multiple progressive, recurrent, and de novo fusiform aneurysms of the left anterior cerebral circulation over 16 years. Because the long-term course of his treatment coincided with the recent expansion of endovascular treatment options, he underwent every type of treatment listed above.

LESSONS

This case demonstrates the wide range of therapeutic options for fusiform aneurysms and how the treatment model for these lesions has evolved.

Congenital internal carotid artery hypoplasia: A systematic review

This review evaluates the current evidence for the clinical management of congenital internal carotid artery hypoplasia (CICAH). We summarise clinical presentations diagnostic standards, imaging recommendations, treatment and follow-up. The review was prompted by a case of CICAH in a 50-year-old female who presented to our neurosurgery clinic with an acute episode of vertigo. The patient underwent CT angiogram, which showed an unusually low right carotid bifurcation. The right internal carotid artery (ICA) was hypoplastic, and the A1 segment of the anterior cerebral artery (ACA) was absent. Skull base CT showed an ipsilateral hypoplastic carotid canal. To summarise current evidence for clinical management of CICAH we followed PRISMA guidelines to identify papers meeting our predefined inclusion criteria. We searched three databases using the terms 'ICA' and 'Hypoplasia'. We reviewed 41 papers meeting our criteria. 34 were clinical reports. We performed a data extraction and quality appraisal on these reports. We found that CICAH may be less rare than previously described. Blood pressure control in CICAH is crucial due to the increased risk of stroke and aneurysm formation. Follow-up imaging is strongly recommended. Carotid doppler sonography is a powerful and underutilised diagnostic tool, and carotid canal hypoplasia is not a pathognomic sign. In conclusion, clinicians should be alert to anatomic variations such as CICAH because these produce haemodynamic changes that may have serious clinical consequences. We recommend a central registry of patients with CICAH in order to understand the longer-term natural history of the condition.

Anatomical variations in the Circle of Willis and the formation and rupture of intracranial aneurysms: A systematic review and meta-analysis

Background

The anterior (AcomA) and posterior communicating arteries (PcomA) are two of the most frequent sites for intracranial aneurysms. Anatomical variations in the Circle of Willis (COW) are frequently observed in patients with AcomA and PcomA aneurysms. Strong evidence is needed to determine the pooled estimate of the effect of COW variations on the formation and rupture of these aneurysms.

Aim

This systematic review and meta-analysis aimed to establish the effect of COW variations on the formation and rupture of AcomA and PcomA aneurysms using available studies.

Summary of review

PubMed, Embase, and Web of Science databases were systematically searched for studies published in English before September 21, 2022. Studies investigating AcomA aneurysms and the hypoplastic/aplastic A1 segment of the anterior cerebral artery and PcomA aneurysms and hypoplastic/aplastic PcomA or fetal-type posterior cerebral artery (FTP) were included. The heterogeneity of the studies was assessed using Cochran Q-test and I² statistic. Pooled estimate was assessed using either a random- or fixed-effects model based on the heterogeneity of the studies. Among the 4,932 studies, 21 were eligible and included in the analysis. The presence of hypoplastic/aplastic A1 was significantly correlated with the formation [OR (95% confidence interval [CI]) = 7.97 (5.58, 11.39), P < 0.001] and rupture [OR (95%CI) = 1.87 (1.29, 2.72), P < 0.001] of AcomA aneurysms. Significant associations between FTP and both the formation [OR (95%CI) = 2.15 (1.41, 3.30), P < 0.001] and rupture [OR (95%CI) = 1.72 (1.26, 2.36), P < 0.001] of PcomA aneurysms were observed.

Conclusions

Significant associations were observed between COW variations and both the formation and rupture of AcomA and PcomA aneurysms. This can help in determining interventions for patients with aneurysms.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=225149, identifier: CRD42021225149.

Concurrence of multiple aneurysms, extreme coiling of the extracranial internal carotid artery and ipsilateral persistent primitive hypoglossal artery: A case report and literature review

Background

The primitive hypoglossal artery (PHA) is an anastomotic vessel of the carotid-basilar artery system that is prevalent only transiently during the embryonic period. Persistent primitive hypoglossal artery (PPHA) is a rare vessel variation in which PHA exists persistently in adulthood and occurs in approximately 0.02-0.1% of the population. Tortuosity of the extracranial internal carotid artery (ICA) is relatively common, impacting 10-43% of the population, and is caused by either congenital or acquired factors. It is still unknown whether PPHA and tortuosity of extracranial ICA are associated. Here, we present a case report of the concurrence of three types of pathologies of the carotid artery: extreme coiling of the extracranial internal carotid artery, multiple aneurysms and persistent primitive hypoglossal artery.

Case description

A 66-year-old woman suffered intermittent headaches, dizziness and numbness of the right eyelid for 5 years. Magnetic resonance angiography performed in a local hospital reported an aneurysm of the posterior communicating artery segment of the left ICA and a left PPHA. Digital subtraction angiography conducted after admission showed a PPHA originating from the left cervical ICA and an extremely coiling segment of the ICA distal to the beginning of PPHA. Except for the aneurysm of the posterior communicating artery segment of the left ICA, multiple aneurysms were found at the coiling segment of the ICA.

Conclusion

To the best of our knowledge, this is the first report of PPHA accompanied by an adjacent, extremely coiling ICA. There are no reports of similar tortuous ICAs to this extent or at this position. Including aneurysms, three types of pathologies suggest their congenital origin, and a review of the literature infers the probable association of these lesions.

Evaluation of Circle of Willis variants using magnetic resonance angiography

The Circle of Willis (COW) is an important collateral pathway to protect the persistence of cerebral blood perfusion. This study aims to investigate the morphological variants of this significant vascular structure with a large study population. 867 patients who had undergone MR angiography (MRA) evaluation were enrolled in this study. The MRA images of these patients obtained by the three-dimensional time-of-flight technique were re-interpreted to measure the vessel diameters of all components of the COW and classify the COW variations. In addition, correlations of the vessel calibers and the integrity of the COW with gender and age groups were presented. There was female dominance in the study population, and the mean age was 48. Type A was the most common variation in anterior (75.78%) and posterior (53.98%) circulation. Types G and H were the other common variation in the anterior circulation, and types E and D were the second and third common variations in the posterior COW, respectively. Smaller calibration for both ICAs, both P1s and BA were observed in females compared with the male group. Diameters of the BA, and both P1 segments were lower, and the left PCom diameter was significantly higher in the patients with a complete circle. There was a significant sex and age difference regarding the distribution of the complete, partially complete, and incomplete circle groups. The significant differences in the vessel calibers of specific components of the COW for complete, partial, and incomplete circulations revealed by this study should be explained with further research. In addition, meta-analyses with other studies in the literature might be a guide to understanding the morphological alterations of the COW and their relationships with a complete and non-complete circle.

Anatomical labeling of intracranial arteries with deep learning in patients with cerebrovascular disease

Brain arteries are routinely imaged in the clinical setting by various modalities, e.g., time-of-flight magnetic resonance angiography (TOF-MRA). These imaging techniques have great potential for the diagnosis of cerebrovascular disease, disease progression, and response to treatment. Currently, however, only qualitative assessment is implemented in clinical applications, relying on visual inspection. While manual or semi-automated approaches for quantification exist, such solutions are impractical in the clinical setting as they are time-consuming, involve too many processing steps, and/or neglect image intensity information. In this study, we present a deep learning-based solution for the anatomical labeling of intracranial arteries that utilizes complete information from 3D TOF-MRA images. We adapted and trained a state-of-the-art multi-scale Unet architecture using imaging data of 242 patients with cerebrovascular disease to distinguish 24 arterial segments. The proposed model utilizes vessel-specific information as well as raw image intensity information, and can thus take tissue characteristics into account. Our method yielded a performance of 0.89 macro F1 and 0.90 balanced class accuracy (bAcc) in labeling aggregated segments and 0.80 macro F1 and 0.83 bAcc in labeling detailed arterial segments on average. In particular, a higher F1 score than 0.75 for most arteries of clinical interest for cerebrovascular disease was achieved, with higher than 0.90 F1 scores in the larger, main arteries. Due to minimal pre-processing, simple usability, and fast predictions, our method could be highly applicable in the clinical setting.

Delineating septo-optic dysplasia

BACKGROUND

Septo-optic dysplasia (SOD), once a variable triad of septum pellucidum defects (SPDs), optic nerve hypoplasia (ONH), and hypopituitarism, has had multiple findings added, with uncertain causes, definitions, and limits.

METHOD

Literature review.

RESULTS

SOD is a complex vascular sequence with confounders.

CONCLUSIONS

Proximal anterior cerebral artery trunk disruptions cause overlapping primary effects, giving ONH alone most often, and isolated SPD less. ONH disruptions can spread to pituitary, SPD disruptions to the cerebral cortex, causing schizencephaly and related anomalies. Pituitary defects are rare without ONH, and cortical findings are rare without SPD. Extensions are unidirectional, so isolated pituitary or cortical defects are separate from SOD. Micro- an- ophthalmia, a suggested ONH variant, is not part of SOD. Disruption by-products can affect development, causing cognitive and endocrine issues, and structural anomalies such as corpus callosum thinning, ventriculomegaly, and hippocampal and olfactory findings. Limbic extensions may also contribute to the same structural defects as by-products. Midline CNS developmental anomalies can act as disruptive foci, most likely through vascular variants, but have separate pathogenesis. Relative frequencies of specific pituitary hormone defects change as SOD rates increase. Increasing relative rates of midline CNS developmental defects and cortical anomalies are consistent with rising levels of exogenous exposures sensitizing to midline predispositions.

A Simple Review of Small Vessel Disease Manifestation in the Brain, Retina, and Kidneys

Small blood vessels express specific phenotypical and functional characteristics throughout the body. Alterations in the microcirculation contribute to many correlated physiological and pathological events in related organs. Factors such as comorbidities and genetics contribute to the complexity of this topic. Small vessel disease primarily affects end organs that receive significant cardiac output, such as the brain, kidney, and retina. Despite the differences in location, concurrent changes are seen in the micro-vasculature of the brain, retina, and kidneys under pathological conditions due to their common histological, functional, and embryological characteristics. While the cardiovascular basis of pathology in association with the brain, retina, or kidneys has been well documented, this is a simple review that uniquely considers the relationship between all three organs and highlights the prevalence of coexisting end organ injuries in an attempt to elucidate connections between the brain, retina, and kidneys, which has the potential to transform diagnostic and therapeutic approaches.

Bilateral aplasia of the anterior cerebral artery in the presence of its vascular source: a case report

PURPOSE

Our goal was to investigate the cases of bilateral aplasia of the anterior cerebral artery (ACA).

METHODS

The macro- and microdissection of the target human brain arteries of 388 cadaveric cases was applied under the magnifying glass. Each case was photographed and diagrammatically represented in the workbook. The length and the outer diameter of the corresponding arteries on the photos were measured using a computer software program.

RESULTS

There was only one case (1/388 or 0.25%) of bilateral ACA aplasia that belonged to a male adult cadaver. Except for the variations of the posterior communicating artery on one side and the basilar artery, the instance of cerebral pathology was not recorded in this case. We compared the recent case with available literature cases.

CONCLUSION

Summarizing small number of literature cases, the recent case of bilateral ACA aplasia as the fifth case discovered so far, represents a true morphological rarity.

Anatomical effects on the relationship between brain arterial diameter and length: The Northern Manhattan Study

BACKGROUND AND PURPOSE

In patients with dolichoectasia, it is uncertain how dilatation and/or elongation relate to each other. We aimed to examine the correlation between arterial diameter and length within arteries and across the circle of Willis (COW).

METHODS

We included stroke-free participants in the Northern Manhattan Study who underwent magnetic resonance angiography. Intracranial artery diameters and lengths were obtained with semiautomated commercial software and were adjusted for head size. We first investigated the correlation between diameters and length using Pearson's correlation coefficient. We then built generalized linear models adjusted for demographics and risk factors.

RESULTS

Among 1210 participants included in the analysis (mean age 71 ± 9 years, 59% women, 65% Hispanic), a larger basilar artery (BA) diameter correlated with greater BA length (r = .3), and left and right middle cerebral artery (MCA) diameters correlated with one another (r = .4). Across the COW, BA diameter correlated with MCA diameters (r = .3 for both). In adjusted analyses, MCA diameters were associated with larger posterior circulation diameters (β = 0.07), MCA and BA lengths (β = 0.003 and β = 0.002, respectively), presence of fetal posterior cerebral artery (PCA), (β = 0.11), and a complete COW (β = -0.02). Similarly, BA length was associated with a fetal PCA (β = 1.1), and BA diameter was associated with anterior circulation diameters (β = 0.15) and presence of fetal PCA (β = -0.4).

CONCLUSIONS

COW configuration should be considered when using arterial diameter cutoffs to define dolichoectasia. Further studies are needed to discern whether arterial diameter or length best identify individuals at risk of vascular events attributable to dolichoectasia.

Ruptured peripheral superior cerebellar artery dissecting aneurysms associated with primitive trigeminal artery: a case report

Background

Persistent primitive trigeminal artery (PPTA) is a remnant of the carotid-vertebrobasilar anastomoses in the embryo. Although PPTAs are discovered incidentally in most cases, altered hemodynamics may lead to increased risk of stroke. To the best of our knowledge, no reports of PPTA associated with superior cerebellar artery (SCA) dissecting aneurysms have been published in the English language.

We describe the case of a patient who presented with subarachnoid hemorrhage (SAH) due to ruptured peripheral SCA dissecting aneurysms in association with PPTA. Additionally, we discuss the relationship between PPTA and peripheral SCA aneurysms and the treatment of peripheral SCA aneurysms.

Case presentation

A 43-year-old woman presented with acute onset of headache and nausea and admitted to our hospital. She was diagnosed with SAH due to ruptured left SCA dissecting aneurysm(s) and had undergone digital subtraction angiography. The left vertebral angiography showed aneurysmal dilatations of the left S2 segment (lateral pontomesencephalic segment) along with dissection through the segments of S2 and S3 (cerebellomesencephalic segment). It also showed ipsilateral PPTA. The left vertebral artery (VA) had normal caliber and the basilar artery segment proximal to the orifice of the left PPTA was not hypoplastic. The patient underwent proximal parent artery occlusion at the S2 segment via the left VA and was successfully treated with no neurological deficits having lasted 5 months.

Conclusions

The flow alteration with PPTA may have influenced the formation of SCA dissection in this patient. Further studies are needed to understand the etiology and treatment outcomes of peripheral SCA aneurysms better.

ATHEROMATOSIS OF THE BRAIN-SUPPLYING ARTERIES: CIRCLE OF WILLIS, BASILAR, VERTEBRAL AND THEIR BRANCHES

PURPOSE

Atherosclerotic plaques in the brain-supplying arteries are slowly-developing alterations of vascular structures that can lead to neurological impairment due to stenosis and insufficient oxygenation of eloquent brain areas. The aim of this study is to provide detailed demographic information related to the incidence of atherosclerotic plaques in the cerebral arteries.

MATERIAL AND METHODS

Forty-eight circles of Willis (21 men, 21 women, mean age: 70.26, six samples unknown) were macroscopically analyzed for length, diameter, and presence of atherosclerotic plaques. Statistical analysis was used to identify potential differences in the locations and frequencies of atherosclerotic plaques in relation to age and sex.

RESULTS

The study sample revealed 261 atherosclerotic plaques. The key findings were significant correlations between plaque development and age and between plaque location and age; however, there was no significant sex difference.

CONCLUSION

The upper and lower branches of the middle cerebral artery (MCA) were novel locations predisposing to plaque development. A cut-off value at 60 years revealed a significant difference in plaque development and distribution. There were no significant sex differences in the occurrence of atherosclerotic plaques.

A Rare Case of Congenital Internal Carotid Artery Agenesis and Contralateral Internal Carotid Artery Aneurysm

Agenesis of the internal carotid artery (ICA) is a rare congenital entity. This anomaly is typically occult in nature. However, the effects of an incidental discovery secondary to a contralateral ICA aneurysmal rupture can be devastating. The association between agenesis of the ICA and contralateral intracranial aneurysm formation is significantly higher than de novo incidental intracranial aneurysms in the general population. It is important to evaluate the presence of a contralateral intracranial aneurysm in the setting of known agenesis of the ICA. This allows for the performance of prophylactic embolization and characterizes collateral cerebral circulation.

Bilateral type IIpersistent proatlantal intersegmental artery: a rare variant of persistent carotid-vertebrobasilar anastomoses

The persistent proatlantal intersegmental artery is a rare variant of persistent carotid-vertebrobasilar anastomoses, especially their bilateral presence is rarer. We report a case of bilateral typeII persistent proatlantal intersegmental artery. The absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent time-of-flight MR angiography confirmed this. The bilateral typeIIpersistent proatlantal intersegmental artery arose from the cervical external carotid artery, penetrated the C1 transverse foramen, entered the skull via the foramen magnum, and joined the lower portion of the basilar artery.

Cerebral Arterial Asymmetries in the Neonate: Insight into the Pathogenesis of Stroke

Neonatal and adult strokes are more common in the left than in the right cerebral hemisphere in the middle cerebral arterial territory, and adult extracranial and intracranial vessels are systematically left-dominant. The aim of the research reported here was to determine whether the asymmetric vascular ground plan found in adults was present in healthy term neonates (n = 97). A new transcranial Doppler ultrasonography dual-view scanning protocol, with concurrent B-flow and pulsed wave imaging, acquired multivariate data on the neonatal middle cerebral arterial structure and function. This study documents for the first-time systematic asymmetries in the middle cerebral artery origin and distal trunk of healthy term neonates and identifies commensurately asymmetric hemodynamic vulnerabilities. A systematic leftward arterial dominance was found in the arterial caliber and cortically directed blood flow. The endothelial wall shear stress was also asymmetric across the midline and varied according to vessels’ geometry. We conclude that the arterial structure and blood supply in the brain are laterally asymmetric in newborns. Unfavorable shearing forces, which are a by-product of the arterial asymmetries described here, might contribute to a greater risk of cerebrovascular pathology in the left hemisphere.