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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.

Craniopharyngiomas in the retrochiasmatic space may extend into the third ventricle. The extended endoscopic endonasal approach (EEEA) provides direct access to the tumor with minimal manipulation of the perforating arteries from the circle of Willis, avoiding brain retraction. EEEA allows a clear view of the hypothalamic wall and tumor interface, preventing hypothalamic injury. In this case, the tumor, located between the optic tract and hypothalamus, was completely resected while preserving the hypothalamus and vascular perforators.By Prakash Nair; M. Gowtham; Akhilesh Gowda and Ashutosh CarpenterReported by Author; Author; Author; Author [Extracted from the article]

The article published in the Journal of Neurological Surgery focuses on the microanatomy of the temporal division of the facial nerve in the periorbital region, specifically for minimally invasive keyhole approaches (MIKA) to the anterior skull base and circle of Willis. The study aims to define a safe zone for skin incisions during MIKA by identifying reliable skin landmarks to avoid the branches of the temporal division of the facial nerve. Through cadaveric dissections, the researchers found a semicircular area around the lateral canthus with a low chance of containing a temporal division branch, providing a clinically applicable landmark for surgical planning in the superolateral region of the orbit. [Extracted from the article]

The article published in the Journal of Neurological Surgery discusses a new hemodynamic classification system for cerebral arteriovenous malformations (AVMs) to predict the risk of hemorrhage. The study analyzed angiograms of AVM patients and found that the proposed classification system could predict the risk of bleeding, independent of other known risk factors. The classification system categorized AVMs into low, medium, or high risk of bleeding based on blood flow velocity and angioarchitecture, providing valuable insights for treatment decisions. [Extracted from the article]

Purpose: Despite significant improvements in the design and performance of continuous flow left ventricular assist devices (CFLVADs), one of the most important reasons hampering further penetration of this technology is the occurrence of adverse events, especially strokes. One of the well-known risk factors for strokes is hypertension which is particularly common in patients undergoing a CFLVAD implant. While the device is implanted in the heart, strokes happen due to pathology in the brain and we hypothesised that modelling the blood flow in the circle of Willis might shed light on the causation of strokes in this situation. The aim of the study was two-fold: 1. What is the reason for hypertension in CFLVADs? Are there physical factors at play, besides neurohumoral mechanisms? 2. Do anatomical factors in the circle of Willis play a role in the causation of strokes in these patients? Methods: The circle of Willis is often incomplete and has a number of anatomical variations, the commonest being the absence of the posterior communicating artery. Hypertension is common after CFLVAD implantation and is also a well-known risk factor for strokes. We examined the blood pressure in the cerebral circulation with pulsatile and non-pulsatile flow for identical conditions and the effect of the absence of the posterior communicating artery on regional cerebral blood flow and pressure. One-dimensional blood flow model was used, taking into account wave propagation and reflections and physiological data obtained from anatomically detailed arterial network (ADAN86) which has data from 86 arteries including detailed cerebral network. Results: The mean arterial pressure was significantly higher in the non-pulsatile blood flow of CFLVADs compared to pulsatile flow, for identical conditions, across all arteries. With increasing imparted pulsatility to CFLVAD flow, the mean arterial pressure progressively decreased. Isolated absence of the posterior communicating artery had no effect on the flow as well as pressure in the middle cerebral artery. However, when combined with the absence of flow in the ipsilateral carotid artery, the flow as well as the pressure decreased very significantly in both continuous and pulsatile flow situations. Conclusions: Physiologically significant pulsatility in CFLVADs can have important clinical advantages in lowering of blood pressure which can lead to lower incidence of strokes, pump thrombosis, gastrointestinal (GI) bleeds, and aortic incompetence. Patient-specific anatomical variations in the circle of Willis, especially the absence of the posterior communicating artery, can have important consequences in regional cerebral perfusion under some circumstances. [ABSTRACT FROM AUTHOR]

Background: Preterm birth (< 37 weeks' gestation) alters cerebrovascular development due to the premature transition from a foetal to postnatal circulatory system, with potential implications for future cerebrovascular health. This study aims to explore potential differences in the Circle of Willis (CoW), a key arterial ring that perfuses the brain, of healthy adults born preterm. Methods: A total of 255 participants (108 preterm, 147 full-term) were included in the analysis. High-resolution three-dimensional Time-of-Flight Magnetic Resonance Angiography (3D TOF MRA) datasets were analysed, measuring vessel diameters and classifying segments into different groups of CoW anatomical variations. Statistical comparisons assessed the prevalence of each variant group between preterm and full-term populations, as well as the relationship between CoW variability, sex, and degree of prematurity. Results: We identified 164 participants with variant CoW configurations. Unilateral segment hypoplasia (30%) and unilateral segment absence (29%) were the most common variations, with over 50% related to the posterior communicating artery (PComA). However, the incidence of absent segments was lower in preterm adults, who were more likely to exhibit variants associated with complete CoW configurations compared to full-term adults (p = 0.025). Preterm males had a higher probability of a group 1 variant (circles with one or more hypoplastic segments only) than the full-term group (p = 0.024). In contrast, preterm females showed higher odds of a group 4a variant (circles with one or more accessory segments, without any absent segments) in comparison to their full-term counterparts (p = 0.020). Conclusions: Preterm birth is linked to a distinct vascular phenotype of CoW in adults born preterm, with a higher likelihood of a CoW configuration with hypoplastic segments but a lower likelihood of absent segments. Future work should focus on larger prospective studies and explore the implications of these findings for normal development and cerebrovascular disease. Furthermore, TOF MRA might be a useful adjunct in the neurovascular assessment of preterm-born individuals. [ABSTRACT FROM AUTHOR]

Background: This study aims to investigate how A1 segment asymmetry—also known as A1 dominancy—influences the development of the anterior communicating artery aneurysm (AcomA) as it affects hemodynamic conditions within the circle of Willis (COW). Using time-of-flight magnetic resonance angiography (TOF-MRA), the research introduces a novel approach to assessing shear stress in A1 segments to uncover the hemodynamic factors contributing to AcomA formation. Method: An observational study was conducted over 6 years at a tertiary university hospital's outpatient clinic. Recruited patients who underwent TOF-MRA imaging were divided into AcomA and non-AcomA groups. MRA images were analyzed using semi-automatic software (VINT, Mediimg, Inc.) to calculate the signal intensity gradient (SIG), which reflects wall shear stress. The comparison metrics included general demographics, anatomical characteristics, and hemodynamic attributes of the COW, mainly focusing on A1 segment asymmetry. Results: Among the 700 subjects, 106 were categorized into the AcomA group, while 594 were placed in the non-AcomA group. The AcomA group showed a more significant difference in the bilateral A1 diameter (49.0% vs. 20.8%, p < 0.001) and a greater prevalence of unilateral A1 aplasia (32.1% vs. 6.7%, p < 0.001) compared to the non-AcomA group. Increased bilateral A1 asymmetry in the AcomA group corresponded with notable variations in A1 SIG, indicating increased wall shear stress. The occurrence of AcomA is associated with both anatomical factors of the circle of Willis, represented by the bilateral A1 diameter ratio, and hemodynamic factors, represented by the bilateral A1 SIG ratio, suggesting that both factors are almost equally significant. Conclusion: Our findings suggest that A1 segment asymmetry influences hemodynamic changes within the COW, contributing to AcomA formation. Hemodynamic factors provide an intuitive understanding of how anatomical characteristics within the COW can lead to aneurysm development. [ABSTRACT FROM AUTHOR]

Objective: Endovascular mechanical thrombectomy (EVMT) is widely employed in patients with acute intracranial carotid artery occlusion (AIICAO). This study aimed to predict the outcomes of EVMT following AIICAO by utilizing anatomic classification of the circle of Willis and its relative position to the thrombus. Methods: In this study, we retrospectively analyzed a cohort of 108 patients with AIICAO who underwent endovascular mechanical thrombectomy (EVMT) at Shaoxing People's Hospital. Based on variations in the circle of Willis, as well as the size and location of the thrombus occluding the middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral artery (PCA), we classified AIICAO into four grades using digital subtraction angiography (DSA). EVMT was initiated upon admission, and baseline data including demographic characteristics, vascular risk factors, angiographic features, initial National Institutes of Health Stroke Scale (NIHSS) scores, Alberta Stroke Program Early CT Score (ASPECT), and etiology classification were compared across these four grades. The prognosis and mortality rates at 90 days post-stroke were evaluated for the different grades and within each grade, patients were further categorized into two subtypes based on vascular compensation and occluded vessels. Results: Significant differences were observed among the four grades of Willis compensation concerning etiologic classification (p = 0.008), postoperative modified treatment in cerebral ischemia (mTICI, p = 0.017), postoperative symptomatic intracranial hemorrhage (sICH, p = 0.007), NIHSS score at admission (p = 0.001), and favorable outcomes at 90 days (modified Rankin Score 0–2) (p = 0.003). The mortality rate at 90 days exhibited a significant difference across the four grades of Willis compensation (p = 0.05). However, prognosis did not reveal any significant differences among the various subtypes within the same grade (p > 0.05). Conclusion: The assessment of the degree of Willis compensation can be improved by evaluating the integrity of the circle of Willis, as well as the size and location of the clot in cases of isolated internal carotid artery occlusion (iICAo). This approach provides valuable prognostic indicators and important insights for the pre-selection of patients prior to endovascular mechanical thrombectomy (EVMT). [ABSTRACT FROM AUTHOR]

Hypertension, a major modifiable risk factor for cardiovascular diseases, is linked to late-life neurocognitive disorders such as vascular dementia and Alzheimer's disease (AD). This study explores the associations between hypertension, intracranial atherosclerotic disease (ICAD), cerebral small vessel disease (cSVD), and Alzheimer's disease neuropathologic change (ADNC) in a large community-based autopsy study. This cross-sectional study used data from the Biobank for Aging Studies of the University of São Paulo Medical School. Sociodemographic and clinical information was gathered from a reliable next-of-kin informant. Neurofibrillary tangles, neuritic plaques, lacunar infarcts, hyaline arteriolosclerosis, and cerebral amyloid angiopathy were evaluated. Causal mediation analyses with natural effect models were performed to examine indirect associations of hypertension with cerebrovascular pathologies and ADNC through morphometric measurements of intracranial artery lumen obstruction. Hypertensive participants (n = 354) presented a higher rate of stenosed arteries (obstruction ≥ 50 %), critically stenosed arteries (obstruction ≥ 70 %), and more severe ICAD, shown by higher maximum and mean obstruction indexes compared to nonhypertensive participants (n = 166). These measurements of atherosclerosis were associated with neurofibrillary tangles and cSVD lesions. Hypertension was indirectly associated with hyaline arteriolosclerosis and lacunar infarcts through the pathway of ICAD. Presenting hypertension indirectly increased the odds of displaying hyaline arteriolosclerosis by 26 % (95 % CI: 1.08, 1.45, p = 0.002) and lacunar infarcts by 17 % (95 % CI: 1.01, 1.35, p = 0.029). Cognitive and APOE ε4 carrier status did not alter the investigated associations. In this community sample, hypertension was indirectly associated with cSVD through ICAD. • Hypertension was linked to increased severity of ICAD. • ICAD was associated with neurofibrillary tangles and cSVD. • Hypertension was indirectly associated with cSVD through ICAD, but not with ADNC. • APOEε4 did not alter the indirect associations of hypertension with cSVD or AD lesions. [ABSTRACT FROM AUTHOR]

The article discusses two cases of secondary aldosteronism due to fibromuscular dysplasia (FMD) and renal artery stenosis (RAS). Case 1, a 35-year-old female, presented with hypertension and hypokalemia, leading to a diagnosis of FMD. After balloon angioplasty, her blood pressure normalized. Case 2, a 31-year-old female, also had FMD and RAS, which were successfully treated with renal arteriography and balloon dilation. The article emphasizes the importance of recognizing and treating FMD to prevent missed diagnoses and misdiagnoses in clinical practice. [Extracted from the article]

The circle of Willis (CoW) is a circular arrangement of arteries in the human brain, exhibiting significant anatomical variability. The CoW is extensively studied in relation to neurovascular pathologies, with certain anatomical variants previously linked to ischemic stroke and intracranial aneurysms. In an individual CoW, arteries might be absent (aplasia) or underdeveloped (hypoplasia, diameter < 1 mm). As the assessment of such variations is time-consuming and susceptible to subjectivity, robust automatic extraction of personalized CoW topology from time-of-flight magnetic resonance angiography (TOF-MRA) images would highly benefit large-scale clinical investigations. Previous work has sought to extract CoW topology from voxel-based semantic segmentation masks. However, hypoplastic arteries are challenging to recover in voxel-based segmentation. Instead, we propose using a complete CoW as an anatomical prior for extracting all possible CoW arteries as shortest paths between automatically identified anatomical landmarks, guided by automatically determined artery orientation vector fields. These fields are obtained using a scale-invariant and rotation-equivariant mesh-CNN-based model (SIRE). For a 3D TOF-MRA volume, a potentially overcomplete graph of the CoW is thus extracted in which each edge represents an artery. Subsequently, a binary Random Forest classifier labels each artery as normal or hypo-/aplastic. The model was optimized and validated using a data set of 351 3D TOF-MRA scans in a cross-validation setup. We showed that using a shortest path algorithm with a cost function based on local artery orientations results in continuous artery paths, even in hypoplastic cases. We tracked the correct path in the posterior communicating arteries in 70–74% of the cases, an artery that is known to pose challenges in voxel-based segmentation models. Our downstream artery path classifier obtained an average F1 score of 0.91, demonstrating the potential of our proposed framework to extract personalized CoW topology automatically. [ABSTRACT FROM AUTHOR]

Children requiring veno‐arterial extracorporeal membrane oxygenation (VA ECMO) or cardiac surgery often undergo cervical cannulation or carotid artery clamping, which can interrupt cerebral circulation. Inadequate collateral flow through the circle of Willis (CoW) may lead to cerebral ischaemia within the vascular territory and/or watershed regions. Pre‐cannulation survey of the CoW using transcranial Doppler (TCD) ultrasound may be performed to predict and plan neuroprotection. It is important to note in this article TCD refers to Duplex or colour coded trans‐cranial Doppler (TCCD) using radiology‐based machines, which is distinct from the more traditional trans‐cranial Doppler technique that does not incorporate a B‐mode image. This article describes our technique, in use since 2019, to guide surgical approaches and neuroprotective measures when an incomplete CoW is identified. High‐end radiology‐based ultrasound platforms and various transducers are used to assess brain morphology and haemorrhage through the anterior fontanelle in neonates. TCD is performed with the highest frequency transducer possible, utilising Doppler imaging to visualise cerebral arteries. Manual carotid compression can be used to functionally assess collateral flow when segments appear aplastic or hypoplastic. Potential pitfalls include mistaking the anterior choroidal artery for a hypoplastic posterior communicating artery (PCommA). Since implementing this protocol 5 years ago, no catastrophic infarcts related to cervical cannulation have occurred. This technique provides a practical solution for pre‐operative assessment of cerebral collateral circulation in children undergoing VA ECMO or cardiac surgery, allowing for consideration of neuroprotective measures and improving patient safety. [ABSTRACT FROM AUTHOR]

The circle of Willis (COW) refers to the anastomotic arterial network found on the brain base, tasked with provision of collateral circulation aimed at prevention of ischemia. The COW is of immense clinical importance especially with regard to the assessment of neurovascular diseases. Individuals portray significant variations in the COW's anatomical configuration. The present study seeks to evaluate the existing anatomical variations of the COW and within the anterior and posterior segments of the COW. Thus, the study seeks to evaluate the different anatomical variations of the COW and its segments and components within the study population. To attain the set objectives, the present study has utilized the angiographic images for studying the COW variants in patients who underwent cerebral angiography during assessment of different types of cerebral anomalies and conditions. Therefore, this study used conventional angiography as an important tool in the evaluation of the different variations in the COW, and is most appropriate for evaluation of smaller anatomical variations owing to its perfect spatial resolution and portrayal of COW anatomy. The study findings indicated the existence between age and sex, and anatomical variations of the COW, particularly with regard to diameters of COW components like basilar artery (BA), P1, and internal carotid arterys (ICAs). Males had bigger BA, P1 and ICA diameters than females, while individuals aged below 40 years had bigger BA, A1, posterior communicating artery, and ICA diameters than those aged above 40 years. [ABSTRACT FROM AUTHOR]

Introduction: Risk factors for cerebrovascular disease (CVD) are nonmodifiable and modifiable. Non-modifiable factors are represented by: age, family history of CVD, race, sex, history of stroke or transient ischemic attack, and the following are considered modifiable factors: diet rich in fat and salt, sedentary lifestyle, obesity, smoking, hypertension, diabetes mellitus, hypercholesterolemia, arterial disease, peripheral artery disease, atrial fibrillation and sickle cell disease. It appears that modifiable factors are most involved in the occurrence of cerebrovascular disease, with some authors reporting a percentage of up to 90%. Material and method: We present a brief background of the literature on the interrelation between risk factors and the development of cerebrovascular disease in patients with anatomical variants in the Circle of Willis. There were performed a Google Scholar and also a MEDLINE search on PubMed using the following terms: "risk factors, stroke, anatomical variants, Circle of Willis" and "stroke, aneurysm, variants, Circle of Willis". Results and Discussion: Nonmodifiabible risk factors for stroke development are related to age, sex, ethnicity/race, genetical characteristics. Genetical characteristics have been associated with an increase of stroke development: parental or familial stroke history and the presence of a certain genetical mutation that can lead to stroke development. There are mentioned in literature as modifiable risk factors involved in the rupture of intracranial aneurysm: obesity, atherosclerosis, metabolic diseases, high blood pressure, in patients with anatomical variants in the circle of Willis. Anatomical variations in the circle of Willis are associated with increased odds of intracranial aneurysms. Conclusion: Understanding the anatomy of the most common variations and their prevalence in the general population would be indicated for the anticipation of cerebral stroke, either ischemic or hemorrhagic and of the affected regions. [ABSTRACT FROM AUTHOR]

Because of the complexity of the brain and its structures, anatomical knowledge is fundamental in neurosurgery. Anatomical dissection, body preservation, and vascular injection remain essential for training, teaching, and refining surgical techniques. This article explores the historical development of these practices and provides the contextual background of modern neurosurgical cadaveric brain models. Body preservation has ancient beginnings, evident in the Chinchorro mummifications and Egyptian embalming. However, brain preservation techniques for education were scarce until the beginning of the Renaissance in Europe. At the University of Bologna in the 13th century, occasional dissections were performed only in winter because of the lack of preservation techniques. Pope Sixtus IV's 1482 papal bull (official decree) formalized and expanded the use of dissection in medical education, leading to an explosion in anatomical studies. This surge brought advances in body preservation, such as soaking bodies in vinegar and distilled liquors. In subsequent centuries, Andreas Vesalius and Charles Bell advanced brain anatomical techniques and knowledge, combining novel illustrations and instruction. To better understand brain vasculature, Richard Lower developed vascular injection techniques using india ink and spirits of wine, leading to the 1664 description of the circle of Willis by Thomas Willis. In 1868, August Hofmann synthesized formaldehyde, markedly improving tissue preservation. Later, William Kruse introduced latex in 1939, and Sidney Sobin introduced silicone in 1965 for vascular studies. These advancements laid the foundation for modern neurosurgical cadaveric studies, many remaining relevant today. [ABSTRACT FROM AUTHOR]

Background/Objectives: Acute type A aortic dissection is among the many types of catastrophic cardiovascular emergencies. The development of serious morbidity, especially neurological complications after the operation, remains a huge threat. We aimed to present comparatively the results of using unilateral or bilateral antegrade cerebral perfusion to minimize these threats and to demonstrate the postoperative effects of antegrade cerebral perfusion choices. Methods: The 147 patients who underwent emergency acute type A aortic dissection surgery between January 2018 and January 2023 were evaluated retrospectively. The patients were divided into two groups: those who underwent unilateral antegrade cerebral perfusion (Group 1) (n = 89) and those who underwent bilateral antegrade cerebral perfusion (Group 2) (n = 59). Baseline demographics, and preoperative, operative, and postoperative data of patients were compared statistically. Results: When the analyses of baseline demographics, and preoperative and operative data were evaluated, no significant difference was found between the groups. In addition, when comparing postoperative results, no statistical difference was found between the groups except for new-onset permanent neurological complications. The rate of postoperative new-onset permanent neurological complications was found to be 17.9% in group 1, where unilateral antegrade cerebral perfusion was applied, and 5.1% in group 2, where bilateral antegrade cerebral perfusion was applied, and this comparison was statistically significant. Conclusions: The competence of the Willis Polygon should not be relied upon without any evidence, and we believe that bilateral antegrade cerebral perfusion can be performed with a technique that does not compromise surgical comfort. [ABSTRACT FROM AUTHOR]

Simple Summary: The Bawean deer (Axis kuhlii) is a critically endangered small deer species endemic to the island of Bawean in Indonesia. This study aimed to describe the arterial blood supply to the brain in this species using three different angiological methods. This is the first description of this anatomical area in this species of deer. The Bawean deer (Axis kuhlii) is a small deer species endemic to the island of Bawean in Indonesia. The species is listed as critically endangered by the IUCN Red List. The current population is assessed to be less than 500 adults living in the wild. The cerebral arterial circle (also called the circle of Willis) is an anastomosis of arteries that supply the brain. The aim of this study was to describe the arterial vascularization of the brain in this species. Three different methods were used to obtain a complete arterial pattern of this region—latex injection, corrosion cast, and contrast-enhanced computed tomography. The arterial vascularization of the brain was described. The pattern of the arterial vessels supplying the brain in this species was similar to that described previously by ruminants. The vessel with the biggest lumen branching off from the circle of Willis was the medial cerebral artery. The basilar artery is a vessel with a narrow lumen and does not mediate the delivery of blood to the encephalon from the caudal side. The results of the study may be useful in creating veterinary protocols for treating vascular diseases in this species and further studies from the field of pathophysiology or pathology. [ABSTRACT FROM AUTHOR]

Introduction: There is a lack of evidence of flow diversion (FD) safety for aneurysms treatment beyond the circle of Willis. Therefore, we provide a single-center real-world experience with the Silk Vista Baby (SVB). Methods: A single-center database was retrospectively reviewed for aneurysms treated with SVB flow diverters. Demographic information, clinical presentation, radiographic characteristics, procedural complications, and outcomes were assessed. Results: About 57 patients (66.7% female, mean age 54.3 ± 13.2) encompassing 57 aneurysms were included. Overall, 40.4% were ruptured: 68.4% saccular, 17.5% blister, 8.7% fusiform, and 5.3% dissecting. The majority were in the anterior circulation (68.4%), and in 48.2% of cases, the distal vessel diameter was inferior to 2 mm. The symptomatic ischemic rate was 5.2%, with one case due to in-stent thrombosis (1.8%). There were no hemorrhagic complications. Complication rates did not differ between ruptured and unruptured lesions (p = 0.356). There were no cases of delayed aneurysm rupture, and overall mortality was 1.8%. The median follow-up time was 18 ± 12 months. In-stent stenosis rate was 10.5% (6/57), all of which were asymptomatic. At the last follow-up, 70.2% of cases had an adequate occlusion (OKM C and D), and 96.5% had an mRS of 0–2. Conclusion: In our series, SVB was shown to be a safe device in the treatment of not only distal anterior circulation aneurysms but also in the management of complex posterior fossa and ruptured blister aneurysms. Multicenter studies are needed to confirm and generalize these results. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The ultrasonographic evaluation of the brain is widely disseminated, focusing on the transcranial Doppler technique, which allows the evaluation of the flows of the different arteries of the circle of Willis in neurocritical patients. In this context, for a long time the brightness mode (B‐mode) has not been taken into account for the study of the pathology of the central nervous system. However, it has been shown that it can also provide valuable information in neurocritical patients by being able to identify hemorrhagic, tumoral, ischemic, traumatic and inflammatory lesions to mention some of its applications. Due to this, the B‐mode should also be considered as an indispensable tool in the management of neurocritical patients. [ABSTRACT FROM AUTHOR]

Abstract Background The Circle of Willis (CoW) is a crucial cerebral arterial structure that facilitates collateral blood flow to the brain. Anatomical variations within the CoW are prevalent and can have significant clinical implications, particularly concerning strokes, aneurysms and other cerebrovascular disorders. This study aimed to assess the anatomical variations of the CoW in the Ethiopian population presenting with neurological symptoms and to explore the factors associated with these variations. By investigating these relationships, the research seeks to enhance understanding of the CoW's anatomical diversity and its potential impact on cerebrovascular health. Methods A facility-based cross-sectional study was conducted among adult patients undergone brain CT angiography at St. Paul’s Hospital Millennium Medical College. A simple random sampling technique was employed to select participants. Multivariate binary logistic regression analyses were performed to determine relationships between dependent and independent variables. Statistical significance was assessed with a p-value

Abstract Background Preterm birth (

Objective To investigate the efficacy and safety of mechanical thrombectomy in patients with acute progressive ischemic stroke with large vessel occlusion in the anterior circulation. Methods From January 2020 to April 2023, 414 patients with acute progressive ischemic stroke with large vessel occlusion in the anterior cirulation in Hebei General Hospital were included. According to the time of onset and whether the patients underwent mechanical thrombectomy, the patients were divided into direct mechanical thrombectomy group (n = 293), progressive stroke mechanical thrombectomy group (n =45), and standard medical treatment group (n = 76). The modified Rankin Scale (mRS) and modified Thrombolysis in Cerebral Infarction (mTICI) were used to evaluate neurological prognosis and vascular recanalization. The incidence of symptomatic intracranial hemorrhage after treatment and 3⁃month all⁃cause mortality were recorded. Results There was a statistically significant difference in neurological prognosis among the 3 groups (χ2 = 19.572, P = 0.000). The rate of good prognosis in standard medical treatment group was lower than that progressive stroke mechanical thrombectomy group (Z = ⁃ 2.829, P = 0.005) and direct mechanical thrombectomy group (Z = ⁃ 4.422, P = 0.000), while there was no statistically significant difference in the rate of good prognosis between direct mechanical thrombectomy group and progressive stroke mechanical thrombectomy group (Z = ⁃ 0.525, P = 0.600). Logistic regression analysis showed that high National Institutes of Health Stroke Scale (NIHSS) score before treatment (OR = 1.298, 95%CI: 1.216- 1.385; P = 0.000) and standard medical treatment (OR = 7.572, 95%CI: 3.048-18.809; P = 0.000) were the risk factors for poor prognosis, and direct mechanical thrombectomy was the protective factor for good prognosis (OR = 0.431, 95%CI: 0.212-0.879; P = 0.021). There was no statistically significant difference in the vascular recanalization rate between progressive stroke mechanical thrombectomy group and direct mechanical thrombectomy group (χ2 = 0.218, P = 0.640). There was a statistically significant difference in the incidence of symptomatic intracranial hemorrhage after treatment among the 3 groups (χ2 = 6.575, P = 0.037), and direct mechanical thrombectomy group was higher than that of standard medical treatment group (Z = ⁃ 2.376, P = 0.018). There was no statistically significant difference in the 3⁃month all⁃cause mortality (χ2 = 5.178, P = 0.075). Conclusions Mechanical thrombectomy is feasible in patients with acute progressive ischemic stroke with large vessel occlusion in the anterior circulation, and has a good efficacy and safety.

The aim of this study was to evaluate the the measurements of the circle of Willis (CW) arteries diameters in a Romanian population. Material and methods: We performed a retrospective study on a sample of 221 adult patients (≥18 years-old), hospitalized in the Emergency Clinical Hospital “Prof. Dr. N. Oblu” from Iași, Romania, over a period of 12 years, who died during hospitalization and on whom an autopsy was performed. Demographic data (age, gender, residence), causes of death and the outer diameters of CW constituent arteries were collected. There were 221 subjects, who were divided into four groups, according to the association of patient’s cause of death with the presence of anatomical variants of CW. 76.01% of all subjects presented cerebrovascular disease (CVDs) and anatomical variant of the CW, thus representing the great majority. Patients “with CVDs and anatomical variants of CW” were older with about 4 years compared to the other three categories of patients, having an average age of 64.17 ±14.22 years. 56.3% of those “without CVDs and with anatomical variant of CW” and 62.5% of those patients deceased ”with CVDs and anatomical variants of CW” had rural residences. 68.8% of all cases ”without CVDs, but with anatomical variants of CW” were female patients. 37.5% of the patients “with CVDs and anatomical variants of CW” and 43.8% of the patients “without CVDs, but with anatomical variants of CW” lived in the urban environment. Statistically significant differences were observed between the mean outer diameters of the arteries of CW and the patient’s cause of death (p

The Circle of Willis (CoW) serves as the primary source of contralateral blood supply in patients who undergo carotid artery cross-clamping (CC) for carotid endarterectomy (CEA). It has been suggested that the CoW's anatomy influences CEA outcomes. The aim of this study was to evaluate associations between the cerebral collateral circulation, a positive awake test for intraoperative neurologic deficit after carotid CC, and postoperative adverse neurologic events. A systematic review was conducted searching MEDLINE, Cochrane, and Web of Science databases for studies that assessed the cerebral circulation, including CoW variations, using neuroimaging techniques in patients who underwent carotid CC. For the metanalytical incidence, the statistical technique used was weight averaging. Otherwise, descriptive analysis was used due to the excessive heterogeneity of the studies. Eight publications, seven cohort and one case-controlled study, involving 1313 patients who underwent carotid artery CC under loco-regional anesthesia, were included in the systematic review. The incidence of positive awake test in the cohort studies ranged from 4.4% to 19.7%. Carotid artery CC resulted in positive awake test in 5% to 91% of patients with alterations in the anterior portion and in 27% to 74% with alterations in the posterior portion of the CoW. A positive awake test in patients with contralateral carotid stenosis or occlusion ranged from 5.8% to 45.7%. Contralateral carotid stenosis >70% or occlusion were associated with a positive awake test (P <.001). Patients with incomplete CoW did not have statistically significant correlation with intraoperative neurological deficits after CC. Data were insufficient to evaluate the effect of the collateral circulation on early outcome after CEA. In this systematic review, contralateral carotid artery stenosis or occlusion, but not CoW abnormalities, were associated with a positive awake test after carotid artery CC. Further research is needed to evaluate which specific CoW anomaly predicts neurologic deficit after CC and to confirm association between a positive awake test and clinical outcome after CEA. [ABSTRACT FROM AUTHOR]

Background and Objectives: Contralateral A1 and AComA aplasia/hypoplasia are critically important in distal ICA T occlusion as the protective collateral blood supply from the circle of Willis via the anterior communicating artery is compromised. Although the terms aplasia/hypoplasia are used broadly in the literature, the need for concrete measurements and data on their clinical significance is apparent. Features of the individual anatomy of the circle of Willis may determine patient outcomes. We aim to determine the cut-off values of contralateral A1 and AComA segments that determine worse outcomes for patients with acute ischemic stroke with T occlusion of the terminal internal carotid artery. Material and Methods: Retrospective patient data from 2015 to 2020 and prospective data from 2021 to 2022 of 482 patients with diagnosed acute ischemic stroke that underwent mechanical thrombectomy at the Republican Vilnius University Hospital (Vilnius, Lithuania) were obtained. Of these patients, 70 were selected with occlusion of internal carotid artery bifurcation and extension to M1 or A1 segments. For statistically significant interactions, patient data were analyzed using two statistical methods (logistic regression and Multivariate Adaptive Regression Splines (MARS)). Results: The narrowest segment of contralateral A1 and/or AComA was statistically significant for 7-day NIHSS, and the optimal cut-off points for this variable were 1.1 mm (MARS model) and 1.2 mm (logistic regression, p = 0.0079, sensitivity 66.7%, specificity 67.9%). The other considered variables (age, gender, time from last seen well to groin puncture, intravenous recombinant tissue plasminogen activator, admission NIHSS, and ASPECT score) and their interactions were not statistically significant. Conclusions: A negative correlation was found between the narrowest segment and seven days of NIHSS. A larger diameter of contralateral A1 and AComA appears to be essential for better patient outcomes at 7-day evaluation post mechanical thrombectomy. [ABSTRACT FROM AUTHOR]

Background: The recurrent artery of Heubner (RAH) is typically the largest medial lenticulostriate branch of the anterior cerebral artery (ACA). Neurosurgical procedures such as aneurysm treatment on the anterior part of the circle of Willis can result in damage of the RAH leading to neurological deficits. The aim of this study was to identify the gaps and provide comprehensive data on the prevalence and anatomical characteristics of the RAH with neurosurgical considerations. Methods: The major electronic databases were thoroughly searched to identify the eligible studies. The information concerning study type, geographical origin, prevalence of the RAH, course and origin of the RAH, symmetry of origin and number of RAHs in each hemisphere, and morphometric data were extracted. The PRISMA guidelines were rigorously followed throughout the study. The AQUA tool was used to evaluate the reliability of included studies. Results: A total of 34 studies (n = 3645 hemispheres) were included in the meta-analysis. The analysis revealed that the RAH was present in 97.5% (95%CI: 95.5–98.6) of the hemispheres, originating most frequently from the A2 segment (42.2%, 95%CI: 35.0–49.7) or the ACoA-ACA junction (41.6%, 95%CI: 34.0–49.6), and coursing anteriorly (47.6%, 95%CI: 38.7–56.6) or superiorly (43.9%, 95%CI: 34.4–53.8) in relation to ACA. Almost a quarter of patients had more than one RAH, which was on average 22.82 mm (SD: 1.35, 95%CI: 20.16–25.47; I2 = 99.1%, p < 0.01) long and reached 0.76 mm (SD: 0.05, 95%CI: 0.66–0.85; I2 = 99.4%, p < 0.01) in diameter. Conclusions: As the RAH is present in the majority of the population, it is important to be aware of the wide variations in its anatomy. This will help to prevent postoperative neurological deficits by avoiding undesirable complications during surgeries that are performed in close proximity to the anterior segment of the circle of Willis. [ABSTRACT FROM AUTHOR]

Cerebrovascular abnormalities are critical indicators of stroke and neurodegenerative diseases like Alzheimer's disease (AD). Understanding the normal evolution of brain vessels is essential for detecting early deviations and enabling timely interventions. Here, for the first time, we proposed a pipeline exploring the joint evolution of cortical volumes (CVs) and arterial volumes (AVs) in a large cohort of 2841 individuals. Using advanced deep learning for vessel segmentation, we built normative models of CVs and AVs across spatially hierarchical brain regions. We found that while AVs generally decline with age, distinct trends appear in regions like the circle of Willis. Comparing healthy individuals with those affected by AD or stroke, we identified significant reductions in both CVs and AVs, wherein patients with AD showing the most severe impact. Our findings reveal gender-specific effects and provide critical insights into how these conditions alter brain structure, potentially guiding future clinical assessments and interventions. Cerebrovascular abnormalities are key indicators of stroke and neurodegenerative diseases. Here, the authors show evolutionary trends of cortical and vascular volumes across spatial hierarchies with a deep learning-based pipeline and varying volume reductions in different brain pathologies. [ABSTRACT FROM AUTHOR]

The circle of Willis (CoW) is a critical, arterial structure that ensures balanced, cerebral-blood supply. The fetal-type posterior cerebral artery (f-PCA) is a CoW variant that can significantly affect hemodynamics and elevate the risk of cerebrovascular diseases. This study used computational fluid dynamics simulations and a patient-specific, three-dimensional model to evaluate the hemodynamic effects of the f-PCA variants on cerebral-blood flow and key hemodynamic indices—such as time-averaged wall-shear stress (TAWSS), oscillatory shear index (OSI), pulsatility index, and resistive index. The fetal ratio (FR) is defined as the ratio of the diameter of the posterior communicating artery (PCoA) to that of the first segment (P1) of the PCA. Our findings indicate that as the FR increases, the contribution of the basilar artery to the second segment (P2) of PCA decreases significantly. Specifically, the flow rate through ipsilateral P1 decreased by 40.0% for FR = 1 and 70.9% for FR = 2, with the internal carotid artery (ICA) compensating for this reduction. Moreover, variations in f-PCA led to significant increases in TAWSS and OSI in key arterial segments (including the ipsilateral P1, PCoA, and the anterior communicating artery), which are associated with a higher risk of aneurysm initiation and growth. Under conditions of unilateral stenosis in the ipsilateral ICA, f-PCA models exhibit a more complex and pronounced impact on blood flow than models without f-PCA, emphasizing the need for detailed hemodynamic assessments in clinical evaluations and preoperative planning to mitigate the risks associated with CoW anatomical variations. [ABSTRACT FROM AUTHOR]

How do regional brain volume ratios and cerebral blood flow (CBF, mL/min) change with aging, and are there sex differences? This study aimed to comprehensively evaluate the relationships between regional brain volume ratios and CBF in healthy brains. The study participants were healthy volunteers who underwent three-dimensional T1-weighted MRI, time-of-flight MR angiography, and four-dimensional (4D) flow MRI between 2020 and 2022. The brain was automatically segmented into 21 brain subregions from 3D T1-weighted MRI, and CBF in 16 major intracranial arteries were measured by 4D flow MRI. The relationships between segmented brain volume ratios and CBFs around the circle of Willis were comprehensively investigated in each decade and sex. This study included 129 healthy volunteers (mean age ± SD, 48.2 ± 16.8; range, 22–92 years; 43 males and 86 females). The association was strongest between the cortical gray matter volume ratio and total outflow of the intracranial major arteries distal to the circle of Willis (Pearson’s correlation coefficient, r: 0.425). In addition, the mean flow of the total inflow and outflow around the circle of Willis were significantly greater in women than men, and significant left–right differences were observed in CBFs even on the peripheral side of the circle of Willis. Moreover, the correlation was strongest between the left cortical gray matter volume ratio and the combined flows of the left anterior and posterior cerebral arteries distal to the circle of Willis (r: 0.486). There was a trend toward greater total intracranial CBF, especially among women in their 40s and younger, who had a larger cortical gray matter volume. This finding may be one of the reasons for the approximately twofold higher incidence of cerebral aneurysms and subarachnoid hemorrhage, and a threefold higher incidence of migraine headaches. [ABSTRACT FROM AUTHOR]

The effectiveness of various stroke treatments depends on the anatomical variability of the cerebral vasculature, particularly the collateral blood vessel network. Collaterals at the level of the Circle of Willis and distal collaterals, such as the leptomeningeal arteries, serve as alternative avenues of flow when the primary pathway is obstructed during an ischemic stroke. Stroke treatment typically involves catheterization of the primary pathway, and the potential risk of further flow reduction to the affected brain area during this treatment has not been previously investigated. To address this clinical question, we derived the lumped parameters for catheterized blood vessels and implemented a corresponding distributed compartment (0D) model. This 0D model was validated against an experimental model and benchmark test cases solved using a 1D model. Additionally, we compared various off‐center catheter trajectories modeled using a 3D solver to this 0D model. The differences between them were minimal, validating the simplifying assumption of the central catheter placement in the 0D model. The 0D model was then used to simulate blood flows in realistic cerebral arterial networks with different collateralization characteristics. Ischemic strokes were modeled by occlusion of the M1 segment of the middle cerebral artery in these networks. Catheters of different diameters were inserted up to the obstructed segment and flow alterations in the network were calculated. Results showed up to 45% maximum blood flow reduction in the affected brain region. These findings suggest that catheterization during stroke treatment may have a further detrimental effect for some patients with poor collateralization. [ABSTRACT FROM AUTHOR]

Purpose: The variations of Cerebral arterial circle (Circle of Willis) are not rare. The study is done to assess the pattern of the component vessels of its anterior part with regard to Right- Left variations and compare with other studies. Material and method: 56 formalin fixed cadavers were analyzed. The diameter, length and variations of the following vessels were observed: Anterior Cerebral Artery (proximal A1 segment to distal A2 segment) and anterior communicating artery. Statistical analysis was done by Statistica 14.0.1 software. Result: 53.57% had normal anterior cerebral artery- anterior communicating artery complex. Length and diameter were slightly more on left side. Unilateral hypoplasia, Azygos and Tripple Anterior Cerebral Artery was present in 21.43%, 3.57 and 1.78% respectively. Aplastic, double and fenestration type anterior communicating artery were present in 5.3%, 8.92% and 1.78% respectively. Conclusion: Anatomical knowledge of variations should be updated regularly for neurosurgeons, radiologists and clinicians to avoid unexpected consequences. [ABSTRACT FROM AUTHOR]

The text discusses a rare case of postoperative paraplegia due to spinal cord infarction following tricuspid valve replacement surgery. The patient, an 81-year-old man with a history of aortic valve replacement and coronary artery bypass grafting, developed paraplegia after the tricuspid valve surgery. The article highlights the importance of recognizing and managing this catastrophic complication, emphasizing the need for awareness among healthcare providers involved in cardiac surgery to optimize patient care. [Extracted from the article]

Cerebral hyperperfusion occurs in some patients after superficial temporal artery–middle cerebral artery bypass surgery. However, there is uncertainty about cerebral hyperperfusion after bypass for patients with different Circle of Willis (CoW) structures. This study established a lumped–parameter model coupled with one–dimensional model (0–1D), whilst a deep learning model for predicting pressure drop (DLM–PD) caused by stenosis and a cerebral autoregulation model (CAM) were introduced into the model. Based on this model, 9 CoW structural models before and after bypass were constructed, to investigate the effects of different CoW structures on cerebral hyperperfusion after bypass. The model and the results were further validated by clinical data. The MSE of mean flow rates from 0–1D model calculation and from clinical measurement was 1.4%. The patients exhibited hyperperfusion in three CoW structures after bypass: missing right anterior segment of the anterior cerebral artery (mRACA1) (13.96% hyperperfusion); mRACA1 and foetal–type right anterior segment of posterior cerebral artery (12.81%), and missing anterior communicating artery and missing left posterior communicating artery (112.41%). The error between the average flow ratio from the model calculations and from clinical measurements was less than 5%. This study demonstrated that the CoW structure had a significant impact on hyperperfusion after bypass. The general 0–1D model coupled with DLM–PD and CAM proposed in this study, could accurately simulate the hemodynamic environment of different CoW structures before and after bypass, which might help physicians identify high–risk patients with hyperperfusion before surgery, and promote the development of non–invasive diagnosis and treatment of cerebrovascular diseases. [ABSTRACT FROM AUTHOR]

Purpose: Civilian penetrating brain injuries (PBI) caused by firearms are a medical emergency with high rates of morbidity and mortality. The aim of this study was to evaluate the association between trajectory vectors in CT brain angiography and clinical outcomes in patients with civilian gunshots. Methods: This is a retrospective analytical cross-sectional study that includes patients over 15 years of age with PBI due to firearms, admitted from January 2019 to December 2021 at a University Hospital in Cali, Colombia. A brain CT with angio-CT was performed the first day of admission. An XYZ coordinate system centered on the Turk's saddle was developed. Trajectories of projectiles were plotted and compared to a patient 0 in a 3D-Slicer software. A bivariate analysis of the clinical and geometric characteristics of the trajectory was performed. Primary outcomes include mortality and disability at 6 months. Results: Twenty-eight patients with a mean age of 27.39 ± 11.66 years were included. The vectors of non-survivors show a trend, crossing at a specific area. This area was designated as a "potential lethal zone" and inside this area, injuries around 25.3 mm from the circle of Willis, were associated with greater mortality (p < 0.005). Conclusions: In our study PBI avoiding the ventricular system, brain stem, dorsum sellae and the circle of Willis were associated with more survivability. A "potential lethal zone" was detected and associated with poor outcome after civilian PBI due to firearms. A better evaluation of the performance of this "potential lethal zone" in larger studies will be required. [ABSTRACT FROM AUTHOR]

Background: Hypertension‐induced impairment of the cerebral artery network contributes to cognitive impairment. Characterizing the structure and function of cerebral arteries may facilitate the understanding of hypertension‐related pathological mechanisms and lead to the development of new indicators for cognitive impairment. Purpose: To investigate the associations between morphological features of the intracranial arteries distal to the circle of Willis on time‐of‐flight MRA (TOF‐MRA) and cognitive performance in a hypertensive cohort. Study Type: Prospective observational study. Population: 189 hypertensive older males (mean age 64.9 ± 7.2 years). Field Strength/Sequence: TOF‐MRA sequence with a 3D spoiled gradient echo readout and arterial spin labeling perfusion imaging sequence with a 3D stack‐of‐spirals fast spin echo readout at 3T. Assessment: The intracranial arteries were segmented from TOF‐MRA and the total length of distal arteries (TLoDA) and number of arterial branches (NoB) were calculated. The mean gray matter cerebral blood flow (GM‐CBF) was extracted from arterial spin labeling perfusion imaging. The cognitive level was assessed with short‐term and long‐term delay‐recall auditory verbal learning test (AVLT) scores, and with montreal cognitive assessment. Statistical Tests: Univariable and multivariable linear regression were used to analyze the associations between TLoDA, NoB, GM‐CBF and the cognitive assessment scores, with P < 0.05 indicating significance. Results: TLoDA (r = 0.314) and NoB (r = 0.346) were significantly correlated with GM‐CBF. Multivariable linear regression analyses showed that TLoDA and NoB, but not GM‐CBF (P = 0.272 and 0.141), were significantly associated with short‐term and long‐term delay‐recall AVLT scores. These associations remained significant after adjusting for GM‐CBF. Data Conclusion: The TLoDA and NoB of distal intracranial arteries on TOF‐MRA are significantly associated with cognitive impairment in hypertensive subjects. Level of Evidence: 2 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Background: Compromised cerebral blood flow can contribute to future ischemic events in patients with symptomatic carotid artery disease. However, there is limited knowledge of the effects on cerebral hemodynamics resulting from a reduced internal carotid artery (ICA) blood flow rate (BFR). Purpose: Investigate how reduced ICA‐BFR, relates to BFR in the cerebral arteries. Study Type: Prospective. Subjects: Thirty‐eight patients, age 72 ± 6 years (11 female). Field Strength/Sequence: 3‐Tesla, four‐dimensional phase‐contrast magnetic resonance imaging (4D‐PCMRI). Assessment: Patients with ischemic stroke or transient ischemic attack were evaluated regarding the degree of stenosis. 4D‐PCMRI was used to measure cerebral BFR in 38 patients with symptomatic carotid stenosis (≥50%). BFR in the cerebral arteries was assessed in two subgroups based on symptomatic ICA‐BFR: reduced ICA‐flow (<160 mL/minutes) and preserved ICA‐flow (≥160 mL/minutes). BFR laterality was defined as a difference in the paired ipsilateral‐contralateral arteries. Statistical Tests: Patients were grouped based on ICA‐BFR (reduced vs. preserved). Statistical tests (independent sample t‐test/paired t‐test) were used to compare groups and hemispheres. Significance was determined at P < 0.05. Results: The degree of stenosis was not significantly different, 80% (95% confidence interval [CI] = 73%–87%) in the reduced ICA‐flow vs. 72% (CI = 66%–76%) in the preserved ICA‐flow; P = 0.09. In the reduced ICA‐flow group, a significantly reduced BFR was found in the ipsilateral middle cerebral artery and anterior cerebral artery (A1), while significantly increased in the contralateral A1. Retrograde BFR was found in the posterior communicating artery and ophthalmic artery. Significant BFR laterality was present in all paired arteries in the reduced ICA‐flow group, contrasting the preserved ICA‐flow group (P = 0.14–0.93). Data Conclusions: 4D‐PCMRI revealed compromised cerebral BFR due to carotid stenosis, not possible to detect by solely analyzing the degree of stenosis. In patients with reduced ICA‐flow, collaterals were not sufficient to maintain symmetrical BFR distribution to the two hemispheres. Evidence Level: 2 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

A Brain-Computer Interface (BCI) is a system that allows a person to control external devices using only their brain activity. It works by translating brain signals into commands that can be understood by a computer. Several lines of evidence demonstrated the deleterious effect of methamphetamine (MA) on neurological and psychological functions. The use of amphetamines, such as MA, is associated with cerebrovascular complications such as cerebrovascular accidents (CVA), hemorrhage, hypoxic damage and vasculitis. Interestingly, while changes to cerebral blood flow (CBF) in response to acute amphetamine exposure have been reported. Transcranial Color Doppler (TCCD) is a non-invasive medical imaging technique that uses ultrasound waves to measure blood flow velocity in the major arteries of the brain, specifically within the circle of Willis. The research paper you referenced explores the use of TCCD as a potential measurement modality for BCIs. Quantitative electroencephalogram (qEEG) is a powerful tool for understanding brain function qEEG can reveal specific brain wave patterns associated with drug addiction, potentially providing insights into the neurobiological mechanisms underlying cravings, withdrawal symptoms, and relapse risk in Methamphetamine User Disorder (MUD). There is growing research interest in using Transcranial dopller as a measurement modality for BCIs.Here are some of the key considerations for using Transcranial doppler in BCIs: Mental Tasks, signal processing and classification, accuracy and reliability. Transcranial doppler provides information about blood flow in specific arteries but lacks detailed spatial information about brain activity. These patterns could vary depending on the type of drug, the severity of addiction, and individual differences. Transcranial doppler in measuring middle cerebral artery (MCA) blood flow velocity parameters (peak systolic velocity (PSV) and mean flow velocity (MFV)). qEEG can help researchers investigate the complex interplay between addiction and other brain disorders, like depression or anxiety. Characteristic qEEG in drugs addiction Increased Theta (4-8 Hz) and delta (1-4 Hz) brain waves are often associated with sleep and relaxation. However, research has shown that individuals with drug addiction may have increased theta and delta activity, particularly in the frontal and temporal regions of the brain. Altered Beta (13-30 Hz) brain waves are generally associated with wakefulness, alertness, and cognitive processing. Studies have observed both increases and decreases in beta activity in individuals with drug addiction, depending on the type of drug, the stage of addiction, and the specific brain regions being examined. The results of this research have important practical implications for building an diagnostic and functional assement with a better understanding of an using technology. [ABSTRACT FROM AUTHOR]

Cerebral aneurysms, a common yet silent condition, affect many people worldwide. Proper treatment selection is crucial because the disease's severity guides the course of treatment. An aneurysm in the Circle of Willis is particularly concerning due to its potential for rupture, leading to severe consequences. This study aims to predict the rupture status of cerebral aneurysms using a comprehensive dataset of clinical and hemodynamic data from blood flow simulations in real three-dimensional geometries from past patients. The Carreau–Yasuda model was used to capture the effects of shear thinning, considering blood as a non-Newtonian fluid that affects the hemodynamic properties of each patient. This research provides insights to aid treatment decisions and potentially save lives. Diagnosing and predicting aneurysm rupture based solely on brain scans is challenging and unreliable. However, statistical methods and machine learning (ML) techniques can help physicians make more confident predictions and select appropriate treatments. We used five ML algorithms trained on a database of 708 cerebral aneurysms, including three clinical features and 17 hemodynamic parameters. Unlike previous studies that used fewer parameters, our comprehensive prediction approach improved prediction accuracy. Our models achieved a maximum accuracy and precision of 0.79 and a recall rate of 0.92. Given the condition's critical nature, recall is more vital than accuracy and precision, and this study achieved a fair recall score. Key features for predicting aneurysm rupture included aneurysm location, low shear area ratio, relative residence time, and turnover time, which significantly contributed to our understanding of this complex condition. [ABSTRACT FROM AUTHOR]

Introduction: There is considerable variability in the morphology of the circle of Willis (CW) among the general healthy population, but also among neurological and neurosurgical patients. The aim of the present study was to identify on autopsied brains the configuration of the circle of Willis (CW) and to evaluate its possible association with the existence of brain lesions, especially with psychiatric disorders. Material and methods: The present study is a retrospective descriptive one and included 221 adult patients (aged ≥ 18 years), who died in the hospital and were autopsied consecutively over between January 1, 2011 - December 31, 2022) in the Department of Pathology, "Prof. Dr. N. Oblu" Emergency Clinical Hospital, Iasi, Romania. We collected the demographic data of the participants (age, gender and residence), the morphological data related to the causes of death, systemic diseases and diseases of the central nervous system (CNS) that contributed to death, as well as the configuration (typical or atypical) of the circle of Willis (CW). The collected data were systematized and statistically analyzed. Results: The patients' mean age was 63.16 ± 14.73 years, with a male: female ratio of 1.45. 181 patients (81.9% of cases) presented an atypical circle of Willis. 86.9% of all cases presented essential hypertension, and 75.1% had atherosclerosis. The presence of CNS disorders, excluding stroke, were identified in 44.3% of the deceased patients. In terms of type and frequency, these CNS disorders were identified as follows: sequelar stroke (15.4% of all cases), CNS infections (13.1%), primary and secondary CNS tumors (10.0%), neurodegenerative diseases (5.0%), psychiatric disorders (0.5%) and others (0.5%). CNS disorders, excluding stroke, were observed only in 42.0% of patients with atypical configurations of CW, compared to 55.0% of those with typical configurations of CW. In patients with atypical configurations of CW, the most frequent diagnosis was sequelar stroke (17.7% of cases). Psychiatric disorders (0.5% of all cases) were identified only in association with atypical configuration of CW. Conclusion: Psychiatric disorders can be associated with the presence of anatomical variations of the circle of Willis, mainly in elderly male patients. These vascular anomalies represent not only a risk factor for the development of psychiatric disorders, but they are also a prognostic factor as it can contribute to the death of the patients, especially when some vascular risk factors, such as hypertension, type 2 diabetes mellitus, and atherosclerosis are associated. [ABSTRACT FROM AUTHOR]

The Circle of Willis (CoW) is a ring-like network of blood vessels that perfuses the brain. Flow in the collateral pathways that connect major arterial inputs in the CoW change dynamically in response to vessel narrowing or occlusion. Vasospasm is an involuntary constriction of blood vessels following subarachnoid hemorrhage (SAH), which can lead to stroke. This study investigated interactions between localization of vasospasm in the CoW, vasospasm severity, anatomical variations, and changes in collateral flow directions. Patient-specific computational fluid dynamics (CFD) simulations were created for 25 vasospasm patients. Computed tomographic angiography scans were segmented capturing the anatomical variation and stenosis due to vasospasm. Transcranial Doppler ultrasound measurements of velocity were used to define boundary conditions. Digital subtraction angiography was analyzed to determine the directions and magnitudes of collateral flows as well as vasospasm severity in each vessel. Percent changes in resistance and viscous dissipation were analyzed to quantify vasospasm severity and localization of vasospasm in a specific region of the CoW. Angiographic severity correlated well with percent changes in resistance and viscous dissipation across all cerebral vessels. Changes in flow direction were observed in collateral pathways of some patients with localized vasospasm, while no significant changes in flow direction were observed in others. CFD simulations can be leveraged to quantify the localization and severity of vasospasm in SAH patients. These factors as well as anatomical variation may lead to changes in collateral flow directions. Future work could relate localization and vasospasm severity to clinical outcomes like the development of infarct. [ABSTRACT FROM AUTHOR]

Although mice are used extensively to study atherosclerosis of different vascular beds, limited data are published on the occurrence of intracranial atherosclerosis. Since intracranial atherosclerosis is a common cause of stroke and is associated with dementia, a relevant animal model is needed to study these diseases. We examined the presence of intracranial atherosclerosis in different atherogenic mouse strains and studied differences in vessel wall characteristics in mouse and human tissue in search of possible explanations for the differing atherosclerotic susceptibility between extracranial and intracranial vessels. The presence of atherosclerotic plaques was systematically examined from the distal common carotids to the circle of Willis in three atherogenic mouse models. Extra- and intracranial vessel characteristics were studied by immunohistochemistry. All three strains developed atherosclerotic lesions in the common carotids, while no lesions were found intracranially. This coincided with altered vessel morphology. Compared to extracranial sections, intracranially the number of elastic layers decreased, tight junction markers increased, and antioxidant enzyme heme oxygenase (HO)-1 increased. Higher HO-1 expression was also shown in human intracranial arteries. Human brain endothelial cell stimulation with oxidized LDL induced endogenous protective antioxidant HO-1 levels through NRF2 translocation. Intracranial atherosclerosis was absent in three atherogenic mouse models. Intracranial vessel segments showed an increased presence of junction markers in mice and increased HO-1 in both mice and human tissue. We suggest that differences in brain vessel structure and induced antioxidant levels in the brain endothelium found in mouse and human tissue may contribute to the decreased atherosclerosis susceptibility of intracranial arteries.

ObjectiveEndovascular mechanical thrombectomy (EVMT) is widely employed in patients with acute intracranial carotid artery occlusion (AIICAO). This study aimed to predict the outcomes of EVMT following AIICAO by utilizing anatomic classification of the circle of Willis and its relative position to the thrombus.MethodsIn this study, we retrospectively analyzed a cohort of 108 patients with AIICAO who underwent endovascular mechanical thrombectomy (EVMT) at Shaoxing People’s Hospital. Based on variations in the circle of Willis, as well as the size and location of the thrombus occluding the middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral artery (PCA), we classified AIICAO into four grades using digital subtraction angiography (DSA). EVMT was initiated upon admission, and baseline data including demographic characteristics, vascular risk factors, angiographic features, initial National Institutes of Health Stroke Scale (NIHSS) scores, Alberta Stroke Program Early CT Score (ASPECT), and etiology classification were compared across these four grades. The prognosis and mortality rates at 90 days post-stroke were evaluated for the different grades and within each grade, patients were further categorized into two subtypes based on vascular compensation and occluded vessels.ResultsSignificant differences were observed among the four grades of Willis compensation concerning etiologic classification (p = 0.008), postoperative modified treatment in cerebral ischemia (mTICI, p = 0.017), postoperative symptomatic intracranial hemorrhage (sICH, p = 0.007), NIHSS score at admission (p = 0.001), and favorable outcomes at 90 days (modified Rankin Score 0–2) (p = 0.003). The mortality rate at 90 days exhibited a significant difference across the four grades of Willis compensation (p = 0.05). However, prognosis did not reveal any significant differences among the various subtypes within the same grade (p > 0.05).ConclusionThe assessment of the degree of Willis compensation can be improved by evaluating the integrity of the circle of Willis, as well as the size and location of the clot in cases of isolated internal carotid artery occlusion (iICAo). This approach provides valuable prognostic indicators and important insights for the pre-selection of patients prior to endovascular mechanical thrombectomy (EVMT).

The circle of Willis (CoW) is a network of cerebral arteries with significant inter-individual anatomical variations. Deep learning has been used to characterize and quantify the status of the CoW in various applications for the diagnosis and treatment of cerebrovascular disease. In medical imaging, the performance of deep learning models is limited by the diversity and size of training datasets. To address medical data scarcity, generative AI models have been applied to generate synthetic vessel neuroimaging data. However, the proposed methods produce synthetic data with limited anatomical fidelity or downstream utility in tasks concerning vessel characteristics.We adapted the StyleGANv2 architecture to 3D to synthesize Time-of-Flight Magnetic Resonance Angiography (TOF MRA) volumes of the CoW. For generative modeling, we used 1782 individual TOF MRA scans from 6 open source datasets. To train the adapted 3D StyleGAN model with limited data we employed differentiable data augmentations, used mixed precision and a cropped region of interest of size 32 × 128 × 128 to tackle computational constraints. The performance was evaluated quantitatively using the Fréchet Inception Distance (FID), MedicalNet distance (MD) and Area Under the Curve of the Precision and Recall Curve for Distributions (AUC-PRD). Qualitative analysis was performed via a visual Turing test. We demonstrated the utility of generated data in a downstream task of multiclass semantic segmentation of CoW arteries. Vessel segmentation performance was assessed quantitatively using the Dice coefficient and the Hausdorff distance.The best-performing 3D StyleGANv2 architecture generated high-quality and diverse synthetic TOF MRA volumes (FID: 12.17, MD: 0.00078, AUC-PRD: 0.9610). Multiclass vessel segmentation models trained on synthetic data alone achieved comparable performance to models trained using real data in most arteries. The addition of synthetic data to a baseline training set improved segmentation performance in underrepresented artery segments, similar to the addition of real data.In conclusion, generative modeling of the Circle of Willis via synthesis of 3D TOF MRA data paves the way for generalizable deep learning applications in cerebrovascular disease. In the future, the extensions of the provided methodology to other medical imaging problems or modalities with the inclusion of pathological datasets has the potential to advance the development of more robust AI models for clinical applications.

A patient presented with acute onset headache and subsequent unconsciousness. The neurologic exam showed left-sided myoclonic jerking and right flaccid hemiparalysis. Noncontrast computed tomography revealed diffuse subarachnoid hemorrhage (SAH) with acute hydrocephalus. Initial digital subtraction angiography (DSA) showed no culprit source for SAH. Repeat DSA on day 7 after initial presentation raised suspicion for left internal carotid artery ophthalmic segment and left lateral lenticulostriate artery (LSA) aneurysms. A magnetic resonance vessel wall imaging (VWI) exam was performed given the presence of multiple potential culprit aneurysms. Vessel wall enhancement around the dome of the left LSA aneurysm suggested rupture, which then facilitated treatment with surgical clipping. LSA aneurysms are exceedingly rare and challenging to treat. Given the associated high degree of morbidity, expedient diagnosis is critical to direct management. VWI could be a valuable tool for detecting ruptured aneurysms in the setting of angiogram-negative SAH.

Resumen: Introducción: enseñar competencias como el razonamiento terapéutico en casos de eventos cerebrovasculares, analizando el polígono de Willis y relacionarlos con las manifestaciones clínicas, es un reto para los docentes en la actualidad. Este estudio diseñó una estrategia innovadora para estudiantes de Ciencias de la Salud, a través de la música y las TIC, promoviendo el aprendizaje y razonamiento terapéutico sobre la obstrucción de arterias del polígono de Willis y sus manifestaciones. Material y métodos: estudio cualitativo, tipo investigación-acción de 4 fases: 1) evaluación de la estrategia pedagógica previa de la clase, 2) diseño de la estrategia nueva, 3) evaluación cualitativa fundamentada en las neurociencias y la salud colectiva y 4) evolución y transformación de la estrategia. Resultados: se desarrolló una estrategia innovadora de construcción participativa con estudiantes, la cual facilitó la afinidad, interés y remembranza del tema abordado. Conclusión: el aprendizaje de temas complejos en la educación universitaria puede fortalecerse con estrategias mediadas por el arte, las historias y las TIC. Se invita a los profesionales de la salud y docentes a trabajar en estrategias situadas y adaptadas al entorno de forma participativa. Abstract: Introduction: Teaching competencies such as therapeutic reasoning in cases of stroke, analyzing the Willis polygon, and relating them to clinical manifestations is a challenge for educators today. This study aimed to an innovative strategy for health sciences students, through music and ICT, promoting learning and therapeutic reasoning about the obstruction of arteries in the Circle of Willis and its manifestations. Materials and methods: Qualitative study of action research with four phases: 1) Evaluation of the previous pedagogical strategy of the class. 2) Design of the new strategy. 3) Qualitative evaluation based on neurosciences and collective health. 4) Evolution and transformation of the strategy. Results: An innovative strategy of participatory construction was developed with students, which facilitated affinity, interest and remembrance of the topic addressed. Conclusions: Learning complex topics in university education can be strengthened with strategies mediated by art, stories and ICT. Health professionals and teachers are invited to work on strategies situated and adapted to the environment in a participatory way.

This research investigates the Circle of Willis, a critical vascular structure vital for cerebral blood supply. A modified novel dual‐pathway multi‐scale hierarchical upsampling network (HUNet) is presented, tailored explicitly for accurate segmentation of Circle of Willis anatomical components from medical imaging data. Evaluating both the multi‐label magnetic resonance angiography region of interest and the multi‐label magnetic resonance angiography whole brain‐case datasets, HUNet consistently outperforms the convolutional U‐net model, demonstrating superior capabilities and achieving higher accuracy across various classes. Additionally, the HUNet model achieves an exceptional dice similarity coefficient of 98.61 and 97.95, along with intersection over union scores of 73.32 and 85.76 in both the multi‐label magnetic resonance angiography region of interest and the multi‐label magnetic resonance angiography whole brain‐case datasets, respectively. These metrics highlight HUNet's exceptional performance in achieving precise and accurate segmentation of anatomical structures within the Circle of Willis, underscoring its robustness in medical image segmentation tasks. Visual representations substantiate HUNet's efficacy in delineating Circle of Willis structures, offering comprehensive insights into its superior performance. [ABSTRACT FROM AUTHOR]