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22 pages, 1715 KiB  
Article
Differential Gene and Protein Expressions Responsible for Vasomotor Signaling Provide Mechanistic Bases for the Opposite Flow-Induced Responses of Pre- and Post-Circle of Willis Arteries
by Zoltan Nemeth, Krisztian Eros, Gyongyi Munkacsy and Akos Koller
Life 2025, 15(6), 856; https://doi.org/10.3390/life15060856 - 26 May 2025
Viewed by 563
Abstract
Increases in flow elicit dilations in the basilar artery (BA) supplied by the posterior cerebral circulation (PCC), and ensuring efficient blood supply to the circle of Willis in which blood flow and pressure can distribute and equalize, and thus provide the appropriate supply [...] Read more.
Increases in flow elicit dilations in the basilar artery (BA) supplied by the posterior cerebral circulation (PCC), and ensuring efficient blood supply to the circle of Willis in which blood flow and pressure can distribute and equalize, and thus provide the appropriate supply for the daughter branches to reach certain brain areas. In contrast, increases in flow elicit constrictions in the middle cerebral artery (MCA), supplied by the anterior cerebral circulation (ACC) and regulating the blood pressure and flow in distal cerebral circulation. Mediators of flow-dependent responses include arachidonic acid (AA) metabolites and nitric oxide (NO). We hypothesized that mediators of flow-dependent responses are differentially expressed in cerebral arteries of the PCC (CAPCC) and ACC (CAACC). The expressions of key enzymes of the AA pathway—cyclooxygenases (COX1/COX2), cytochrome P450 hydroxylases (Cyp450), thromboxane synthase (TXAS), thromboxane A2 (TP) receptor, prostacyclin synthase (PGIS), prostacyclin (IP) receptor (IP); neuronal nitric oxide synthase (nNOS), and endothelial nitric oxide synthase (eNOS)—in the BA and MCA from rats (n = 20) were determined by western blotting. Transcriptome analysis in CAPCC and CAACC from rats (n = 25) was assessed by RNA sequencing. In BA compared to MCA, COX1/2 and Cyp450 protein expressions were lower, PGIS was higher, TXAS and nNOS/eNOS were similar, TP receptors were lower, and IP receptors were higher. Gene expressions of vasodilator canonical pathways were higher in CAPCC; vasoconstriction canonical pathways were higher in CAACC. Mediators of flow-dependent vasomotor signaling are differentially expressed in cerebral arteries of the posterior and anterior circulation, corresponding to their vasomotor function. Full article
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19 pages, 1163 KiB  
Review
Cerebral Vasospasm as a Critical Yet Overlooked Complication Following Tumor Craniotomy: A Systematic Review of Case Reports and Case Series
by Khairunnisai Tarimah, Dewi Yulianti Bisri, Radian Ahmad Halimi and Elvan Wiyarta
J. Clin. Med. 2025, 14(7), 2415; https://doi.org/10.3390/jcm14072415 - 1 Apr 2025
Viewed by 1329
Abstract
Background: Cerebral vasospasm after craniotomy tumor (CVACT) is a rare complication that can occur following tumor craniotomy and significantly affects the outcome of patients. Unfortunately, it is not well understood, leading to delayed and ineffective management. This study aims to investigate CVACT by [...] Read more.
Background: Cerebral vasospasm after craniotomy tumor (CVACT) is a rare complication that can occur following tumor craniotomy and significantly affects the outcome of patients. Unfortunately, it is not well understood, leading to delayed and ineffective management. This study aims to investigate CVACT by examining the factors contributing to its occurrence, its underlying mechanisms, diagnostic approaches, management strategies, and outcomes. The goal is to identify the characteristics and risk factors associated with CVACT, its clinical symptoms, diagnostic methods, management options, and potential outcomes. Methods: A systematic search used relevant keywords to identify cases of “cerebral vasospasm” after tumor resection in PubMed and Science Direct databases. Relevant cross-references were added by manually searching the references of all retrieved articles. Result: We included 60 inclusion patients from 14 case reports and 13 case series with 33 (55%) females and 27 (45%) males with a mean age of 44.05 ± 16.8 years. The most common tumors were pituitary adenomas, which were found in 22 (36.66%), the most common tumor location was the middle cranial fossa (75%), and the most common surgery technique used was transsphenoidal surgery (50%). Most of those who experience vasospasm have a craniotomy with the TSS technique (50%) with complications of intraoperative bleeding. The range of onset of VS symptoms postoperatively was 0–30 days (mean 6.59 d). The symptoms included asymptomatic, headache, loss of vision, hemiparesis, diplopia, etc. The vascular involvement was mainly anterior circulation (78.33%). The diagnostic tools most commonly used were angiography and transcranial doppler (TCD). The most common management of VS from the included studies was pharmacology. The survival rate was 61.66%. We found the tumor location and vascular-affected vasospasm were significantly correlated with mortality rates: p = 0.015 and p = 0.02. Conclusions: Cerebral vasospasm after craniotomy tumor removal (CVACT) frequently arises in tumors situated in the medial cranial fossa, predominantly pituitary adenomas and meningiomas. The minimally invasive surgical approach of TSS may contribute to the mechanism of CVACT incidence. The existence of preoperative vascular pathology, as encasement or narrowing, appears to be a predictor alongside the incidence of intra- or postoperative hemorrhage. The vascular structures most susceptible to vasospasm are located in the anterior circulation of the Willis circle, which appears to correlate with the vascular problems that typically undergo preoperative encasement of the internal carotid artery (ICA). The most reliable and real time diagnostic instrument employed is TCD, while imaging continues to be the gold standard. Nimodipine treatment continues to be a viable therapeutic option that can enhance patient outcomes. Full article
(This article belongs to the Special Issue Management of Postoperative Care in Neurosurgery)
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29 pages, 2280 KiB  
Article
Geometric Models of Speciation in Minimally Monophyletic Genera Using High-Resolution Phylogenetics
by Richard H. Zander
Plants 2025, 14(4), 530; https://doi.org/10.3390/plants14040530 - 9 Feb 2025
Viewed by 803
Abstract
High-resolution phylogenetics using both morphology and molecular data reveal surfactant-like trait buffering of peripatric descendant species that facilitate resilience for supra-specific entities across geologic time. Regular polygons inscribed in circles model balanced areas of survival of various numbers of new species in one [...] Read more.
High-resolution phylogenetics using both morphology and molecular data reveal surfactant-like trait buffering of peripatric descendant species that facilitate resilience for supra-specific entities across geologic time. Regular polygons inscribed in circles model balanced areas of survival of various numbers of new species in one genus. This model maximizes the peripatric survival of descendant species, with populations partly in allopatric habitats and in sympatric areas. It extends the theory advanced with Willis’s Age and Area hypothesis. Hollow curves of the areas bounded between a series of inscribed regular polygons and their containing circles show a ranked progression governed by similar power laws of other phenomena, including Zipf’s law and a universal meta-law in physics. This model matches best the physics meta-law (law of laws) but is only one of several somewhat different curves generated by somewhat different processes. A rule of four can explain why most genera in vascular plants exhibit a hollow curve of optimally one to five species per genus. It implies a constraint on variation that enhances survival and provides a physics explanation for the monophyletic skeleton of macrogenera. A high-resolution form of ancestor–descendant analysis is compared to traditional phylogenetic analysis to best modeling of the demonstrable results of evolutionary processes. Arguments are advanced for the preservation of scientific concepts of taxa over cladistic clades. Full article
(This article belongs to the Special Issue Evolution of Land Plants)
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9 pages, 3377 KiB  
Communication
The Arterial Circle of the Brain in the Bawean Deer (Axis kuhlii)
by Maciej Zdun, Jakub Jędrzej Ruszkowski, Maria Nabzdyk, Aleksander F. Butkiewicz, Maciej Gogulski and Marcin Gołyński
Animals 2024, 14(23), 3410; https://doi.org/10.3390/ani14233410 - 26 Nov 2024
Viewed by 822
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Advances in Animal Neuroscience)
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12 pages, 3812 KiB  
Article
Cerebral Arterial Inflow and Venous Outflow Assessment Using 4D Flow MRI in Adult and Pediatric Patients
by Ramez N. Abdalla, Susanne Schnell, Maria Aristova, Mohamad Mohayad Alzein, Yasaman Moazeni, Jessie Aw, Can Wu, Michael Markl, Donald R. Cantrell, Michael C. Hurley, Sameer Ansari and Ali Shaibani
J. Vasc. Dis. 2024, 3(4), 407-418; https://doi.org/10.3390/jvd3040032 - 13 Nov 2024
Viewed by 2015
Abstract
Background and Purpose: The cerebral circulation is highly regulated to maintain brain perfusion, keeping an equilibrium between the brain tissue, cerebrospinal fluid (CSF) and blood of the arterial and venous systems. Cerebral venous drainage abnormalities have been implicated in multiple cerebrovascular diseases. The [...] Read more.
Background and Purpose: The cerebral circulation is highly regulated to maintain brain perfusion, keeping an equilibrium between the brain tissue, cerebrospinal fluid (CSF) and blood of the arterial and venous systems. Cerebral venous drainage abnormalities have been implicated in multiple cerebrovascular diseases. The purpose of this study is to evaluate the relationship between the arterial inflow (AI) and the cerebral venous outflow (CVO) and their correlation with the cardiac outflow in healthy adults and children to understand the role of the emissary veins in normal venous drainage. Materials and Methods: A total of 31 healthy volunteers (24 adults (39.5 ± 16.0) and seven children (3.4 ± 2.2)) underwent intracranial 4D flow with full circle of Willis coverage and 2D PC-MRI at the level of the transverse sinus for measurement of the AI and CVO, respectively. The AI was calculated as the sum of the flow values in the bilateral internal carotid and basilar arteries. The CVO was calculated as the sum of the flow values in the bilateral transverse sinuses. The cardiac outflow was measured via 2D PC-MRI with retrospective ECG gating with images acquired at the proximal ascending aorta (AAo) and descending (DAo) aorta. The ratios of the AI/AAo flow and CVO/AI were calculated to characterize the fraction of cerebral arterial inflow in relation to cardiac outflow and venous blood draining through the transverse sinuses, respectively. Results: The AI and CVO were significantly correlated (r = 0.81, p < 0.001). The CVO constituted approximately 60–70% of the AI. The CVO/AI ratio was significantly lower in children versus adults (p = 0.025). In adults, the negative correlation of the AI with age remained strong (r = −0.81, p < 0.001). However, the CVO was not significantly associated with age. Conclusion: The CVO/AI ratio suggests an important role of the emissary veins, accounting for approximately 30–40% of venous drainage. The lower CVO/AI ratio in children, although partially related to decreased AI with age, suggests a greater role of the emissary veins in childhood, which strongly decreases with age. Full article
(This article belongs to the Section Neurovascular Diseases)
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12 pages, 1688 KiB  
Article
Association of Narrow Anterior Communicating Artery or Contralateral A1 Segment with Poor Outcomes After Mechanical Thrombectomy
by Audrius Širvinskas, Giedrius Ledas, Rūta Levulienė, Jurgita Markevičiūtė, Valerija Mosenko, Andrej Afanasjev, Aleksandras Vilionskis, Saulius Lukoševičius and Algirdas Edvardas Tamošiūnas
Medicina 2024, 60(11), 1749; https://doi.org/10.3390/medicina60111749 - 24 Oct 2024
Viewed by 1143
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Section Cardiology)
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11 pages, 1288 KiB  
Review
Lateral Spinal Artery Aneurysm Causing Subarachnoid Hemorrhage: Literature Review and Case Report
by Yoo Sung Jeon, Jeong Jin Park, Young Il Chun and Hong Gee Roh
J. Clin. Med. 2024, 13(16), 4910; https://doi.org/10.3390/jcm13164910 - 20 Aug 2024
Cited by 2 | Viewed by 1543
Abstract
Ruptured aneurysms of the lateral spinal artery (LSA) causing subarachnoid hemorrhage (SAH) are exceptionally rare. Unlike common aneurysms in the circle of Willis, LSA aneurysms present unique diagnostic and therapeutic challenges due to their complex anatomy. We reviewed the literature, examining case reports [...] Read more.
Ruptured aneurysms of the lateral spinal artery (LSA) causing subarachnoid hemorrhage (SAH) are exceptionally rare. Unlike common aneurysms in the circle of Willis, LSA aneurysms present unique diagnostic and therapeutic challenges due to their complex anatomy. We reviewed the literature, examining case reports detailing LSA aneurysm occurrences, diagnoses, treatments, and complications, and our subsequent analysis highlights the clinical presentations, imaging findings, treatment methods, and anatomical features of the LSA. We identified 10 patients from 7 case reports of LSA aneurysm presenting with SAH, and combined with the present case, this comprised a total of 11 patients. An initial CT angiography identified LSA aneurysm in only 2 of 11 patients, while 5 cases were detected in transfemoral cerebral angiography. Seven patients had stenosis or occlusion of nearby arteries. Among the 10 patients treated, 7 underwent microsurgical clipping, and 3 had endovascular treatment; complications included PICA infarction and subdural hematoma. LSA aneurysms, though rare, should be considered in differential diagnoses of posterior fossa SAH. An accurate diagnosis often requires repeated imaging. It is proposed to individualize treatment strategies based on the unique anatomical structure and hemodynamic conditions of each patient, utilizing both endovascular and surgical approaches. Understanding the vascular anatomy and collateral pathways of the LSA is crucial for improving diagnostic accuracy and treatment outcomes. Full article
(This article belongs to the Section Clinical Neurology)
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18 pages, 12890 KiB  
Article
Dimethyl Fumarate Mediates Sustained Vascular Smooth Muscle Cell Remodeling in a Mouse Model of Cerebral Aneurysm
by Alejandra N. Martinez, Giovane G. Tortelote, Crissey L. Pascale, Uduak-Obong I. Ekanem, Ana Paula de O. Leite, Isabella G. McCormack and Aaron S. Dumont
Antioxidants 2024, 13(7), 773; https://doi.org/10.3390/antiox13070773 - 27 Jun 2024
Viewed by 2160
Abstract
Cerebral aneurysms (CA) are a type of vascular disease that causes significant morbidity and mortality with rupture. Dysfunction of the vascular smooth muscle cells (VSMCs) from circle of Willis (CoW) vessels mediates CA formation, as they are the major cell type of the [...] Read more.
Cerebral aneurysms (CA) are a type of vascular disease that causes significant morbidity and mortality with rupture. Dysfunction of the vascular smooth muscle cells (VSMCs) from circle of Willis (CoW) vessels mediates CA formation, as they are the major cell type of the arterial wall and play a role in maintaining vessel integrity. Dimethyl fumarate (DMF), a first-line oral treatment for relapsing-remitting multiple sclerosis, has been shown to inhibit VSMC proliferation and reduce CA formation in a mouse model. Potential unwanted side effects of DMF on VSMC function have not been investigated yet. The present study characterizes the impact of DMF on VSMC using single-cell RNA-sequencing (scRNA-seq) in CoW vessels following CA induction and further explores its role in mitochondrial function using in vitro VSMC cultures. Two weeks of DMF treatment following CA induction impaired the transcription of the glutathione redox system and downregulated mitochondrial respiration genes in VSMCs. In vitro, DMF treatment increased lactate formation and enhanced the mitochondrial production of reactive oxygen species (ROS). These effects rendered VSMCs vulnerable to oxidative stress and led to mitochondrial dysfunction and enhancement of apoptosis. Taken together, our data support the concept that the DMF-mediated antiproliferative effect on VSMCs is linked to disturbed antioxidative functions resulting in altered mitochondrial metabolism. This negative impact of DMF treatment on VSMCs may be linked to preexisting alterations of cerebrovascular function due to renal hypertension. Therefore, before severe adverse effects emerge, it would be clinically relevant to develop indices or biomarkers linked to this disturbed antioxidative function to monitor patients undergoing DMF treatment. Full article
(This article belongs to the Special Issue Glutathione Redox Cycle)
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11 pages, 275 KiB  
Article
Communicating Arteries and Leptomeningeal Collaterals: A Synergistic but Independent Effect on Patient Outcomes after Stroke
by Sara Sablić, Krešimir Dolić, Danijela Budimir Mršić, Mate Čičmir-Vestić, Antonela Matana, Sanja Lovrić Kojundžić and Maja Marinović Guić
Neurol. Int. 2024, 16(3), 620-630; https://doi.org/10.3390/neurolint16030046 - 2 Jun 2024
Viewed by 1639
Abstract
The collateral system is a compensatory mechanism activated in the acute phase of an ischemic stroke. It increases brain perfusion to the hypoperfused area. Arteries of the Willis’ circle supply antegrade blood flow, while pial (leptomeningeal) arteries direct blood via retrograde flow. The [...] Read more.
The collateral system is a compensatory mechanism activated in the acute phase of an ischemic stroke. It increases brain perfusion to the hypoperfused area. Arteries of the Willis’ circle supply antegrade blood flow, while pial (leptomeningeal) arteries direct blood via retrograde flow. The aim of our retrospective study was to investigate the relationship between both collateral systems, computed tomography perfusion (CTP) values, and functional outcomes in acute stroke patients. Overall, 158 patients with anterior circulation stroke who underwent mechanical thrombectomy were included in the study. We analyzed the presence of communicating arteries and leptomeningeal arteries on computed tomography angiography. Patients were divided into three groups according to their collateral status. The main outcomes were the rate of functional independence 3 months after stroke (modified Rankin scale score, mRS) and mortality rate. Our study suggests that the collateral status, as indicated by the three groups (unfavorable, intermediate, and favorable), is linked to CT perfusion parameters, potential recuperation ratio, and stroke outcomes. Patients with favorable collateral status exhibited smaller core infarct and penumbra volumes, higher mismatch ratios, better potential for recuperation, and improved functional outcomes compared to patients with unfavorable or intermediate collateral status. Full article
(This article belongs to the Special Issue Treatment Strategy and Mechanism of Acute Ischemic Stroke)
16 pages, 1033 KiB  
Review
Exploring the Complex Interplay of Obesity, Allergic Diseases, and Sleep-Disordered Breathing in Children
by Chiara Voltan, Francesca Concer, Luca Pecoraro, Angelo Pietrobelli, Giorgio Piacentini and Marco Zaffanello
Children 2024, 11(5), 595; https://doi.org/10.3390/children11050595 - 15 May 2024
Cited by 4 | Viewed by 2604
Abstract
This narrative review study investigates the correlations between obesity, allergies, and sleep-disordered breathing in pediatric populations. Searches for pertinent articles were conducted on the Medline PubMed Advanced Search Builder, Scopus, and Web of Science databases from unlimited to April 2024. Sleep-disordered breathing causes [...] Read more.
This narrative review study investigates the correlations between obesity, allergies, and sleep-disordered breathing in pediatric populations. Searches for pertinent articles were conducted on the Medline PubMed Advanced Search Builder, Scopus, and Web of Science databases from unlimited to April 2024. Sleep-disordered breathing causes repeated upper airway obstructions, leading to apneas and restless sleep. Childhood obesity, which affects around 20% of children, is often associated with sleep-disordered breathing and allergies such as asthma and allergic rhinitis. It is distinguished between diet-induced obesity (resulting from excess of diet and physical inactivity) and genetic obesity (such as is seen in Down syndrome and Prader–Willi syndrome). In children with diet-induced obesity, chronic inflammation linked to weight can worsen allergies and increase the risk and severity of asthma and rhinitis. Furthermore, the nasal congestion typical of rhinitis can contribute to upper respiratory tract obstruction and obstructive sleep apnea. A vicious circle is created between asthma and sleep-disordered breathing: uncontrolled asthma and sleep-disordered breathing can worsen each other. In children with genetic obesity, despite alterations in the immune system, fewer allergies are observed compared to the broader population. The causes of this reduced allergenicity are unclear but probably involve genetic, immunological, and environmental factors. Additional research is necessary to elucidate the underlying mechanisms. The present narrative review study emphasizes the importance of jointly evaluating and managing allergies, obesity, and obstructive sleep apnea in children considering their close interconnection. Full article
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12 pages, 839 KiB  
Article
Geometry and Symmetry of Willis’ Circle and Middle Cerebral Artery Aneurysms Development
by Carmelo Lucio Sturiale, Alba Scerrati, Luca Ricciardi, Oriela Rustemi, Anna Maria Auricchio, Nicolò Norri, Amedeo Piazza, Fabio Raneri, Alberto Benato, Alessio Albanese, Annunziato Mangiola, Donato Carlo Zotta, Giancarlo D’Andrea, Veronica Picotti, Antonino Raco, Lorenzo Volpin and Gianluca Trevisi
J. Clin. Med. 2024, 13(10), 2808; https://doi.org/10.3390/jcm13102808 - 10 May 2024
Cited by 2 | Viewed by 2871
Abstract
Background: A relationship between the geometry and symmetry of Willis’ circle and intracranial aneurysms was reported for anterior communicating and posterior communicating (PCom) aneurysms. A similar association with the middle cerebral artery (MCA) aneurysms instead appeared weaker. Methods: We reviewed 432 [...] Read more.
Background: A relationship between the geometry and symmetry of Willis’ circle and intracranial aneurysms was reported for anterior communicating and posterior communicating (PCom) aneurysms. A similar association with the middle cerebral artery (MCA) aneurysms instead appeared weaker. Methods: We reviewed 432 patients from six Italian centers with unilateral MCA aneurysms, analyzing the relationship between the caliber and symmetry of Willis’ circle and the presence of ruptured and unruptured presentation. CT-angiograms were evaluated to assess Willis’ circle geometrical characteristics and the MCA aneurysm side, dimension and rupture status. Results: The hypoplasia of the first segment of the anterior cerebral artery (A1) was in approximately one-quarter of patients and PCom hypoplasia was in almost 40%. About 9% had a fetal PCom ipsilaterally to the aneurysm. By comparing the aneurysmal and healthy sides, only the PCom hypoplasia appeared significantly higher in the affected side. Finally, the caliber of the internal carotid artery (ICA) and the first segment of MCA (M1) caliber were significantly greater in patients with unruptured aneurysms, and PCom hypoplasia appeared related to the incidence of an ipsilateral MCA aneurysm and its risk of rupture. Conclusions: Although according to these findings asymmetries of Willis’ circle are shown to be a risk factor for MCA aneurysm formation and rupture, the indifferent association with ipsilateral or contralateral hypoplasia remains a datum of difficult hemodynamic interpretation, thereby raising the concern that this association may be more casual than causal. Full article
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21 pages, 944 KiB  
Review
Non-Invasive Tools in Perioperative Stroke Risk Assessment for Asymptomatic Carotid Artery Stenosis with a Focus on the Circle of Willis
by Balázs Lengyel, Rita Magyar-Stang, Hanga Pál, Róbert Debreczeni, Ágnes Dóra Sándor, Andrea Székely, Dániel Gyürki, Benjamin Csippa, Lilla István, Illés Kovács, Péter Sótonyi and Zsuzsanna Mihály
J. Clin. Med. 2024, 13(9), 2487; https://doi.org/10.3390/jcm13092487 - 24 Apr 2024
Cited by 3 | Viewed by 2495
Abstract
This review aims to explore advancements in perioperative ischemic stroke risk estimation for asymptomatic patients with significant carotid artery stenosis, focusing on Circle of Willis (CoW) morphology based on the CTA or MR diagnostic imaging in the current preoperative diagnostic algorithm. Functional transcranial [...] Read more.
This review aims to explore advancements in perioperative ischemic stroke risk estimation for asymptomatic patients with significant carotid artery stenosis, focusing on Circle of Willis (CoW) morphology based on the CTA or MR diagnostic imaging in the current preoperative diagnostic algorithm. Functional transcranial Doppler (fTCD), near-infrared spectroscopy (NIRS), and optical coherence tomography angiography (OCTA) are discussed in the context of evaluating cerebrovascular reserve capacity and collateral vascular systems, particularly the CoW. These non-invasive diagnostic tools provide additional valuable insights into the cerebral perfusion status. They support biomedical modeling as the gold standard for the prediction of the potential impact of carotid artery stenosis on the hemodynamic changes of cerebral perfusion. Intraoperative risk assessment strategies, including selective shunting, are explored with a focus on CoW variations and their implications for perioperative ischemic stroke and cognitive function decline. By synthesizing these insights, this review underscores the potential of non-invasive diagnostic methods to support clinical decision making and improve asymptomatic patient outcomes by reducing the risk of perioperative ischemic neurological events and preventing further cognitive decline. Full article
(This article belongs to the Special Issue Carotid Artery Disease: Latest Update on Diagnosis and Management)
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24 pages, 553 KiB  
Review
Multi-Dimensional Modeling of Cerebral Hemodynamics: A Systematic Review
by Jana Korte, Ehlar Sophie Klopp and Philipp Berg
Bioengineering 2024, 11(1), 72; https://doi.org/10.3390/bioengineering11010072 - 11 Jan 2024
Cited by 2 | Viewed by 3099
Abstract
The Circle of Willis (CoW) describes the arterial system in the human brain enabling the neurovascular blood supply. Neurovascular diseases like intracranial aneurysms (IAs) can occur within the CoW and carry the risk of rupture, which can lead to subarachnoid hemorrhage. The assessment [...] Read more.
The Circle of Willis (CoW) describes the arterial system in the human brain enabling the neurovascular blood supply. Neurovascular diseases like intracranial aneurysms (IAs) can occur within the CoW and carry the risk of rupture, which can lead to subarachnoid hemorrhage. The assessment of hemodynamic information in these pathologies is crucial for their understanding regarding detection, diagnosis and treatment. Multi-dimensional in silico approaches exist to evaluate these hemodynamics based on patient-specific input data. The approaches comprise low-scale (zero-dimensional, one-dimensional) and high-scale (three-dimensional) models as well as multi-scale coupled models. The input data can be derived from medical imaging, numerical models, literature-based assumptions or from measurements within healthy subjects. Thus, the most realistic description of neurovascular hemodynamics is still controversial. Within this systematic review, first, the models of the three scales (0D, 1D, 3D) and second, the multi-scale models, which are coupled versions of the three scales, were discussed. Current best practices in describing neurovascular hemodynamics most realistically and their clinical applicablility were elucidated. The performance of 3D simulation entails high computational expenses, which could be reduced by analyzing solely the region of interest in detail. Medical imaging to establish patient-specific boundary conditions is usually rare, and thus, lower dimensional models provide a realistic mimicking of the surrounding hemodynamics. Multi-scale coupling, however, is computationally expensive as well, especially when taking all dimensions into account. In conclusion, the 0D–1D–3D multi-scale approach provides the most realistic outcome; nevertheless, it is least applicable. A 1D–3D multi-scale model can be considered regarding a beneficial trade-off between realistic results and applicable performance. Full article
(This article belongs to the Section Regenerative Engineering)
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16 pages, 21022 KiB  
Article
Evaluating the Impact of Domain Boundaries on Hemodynamics in Intracranial Aneurysms within the Circle of Willis
by Pablo Jeken-Rico, Aurèle Goetz, Philippe Meliga, Aurélien Larcher, Yigit Özpeynirci and Elie Hachem
Fluids 2024, 9(1), 1; https://doi.org/10.3390/fluids9010001 - 21 Dec 2023
Cited by 6 | Viewed by 2823
Abstract
Hemodynamic simulations are increasingly used to study vascular diseases such as Intracranial Aneurysms (IA) and to further develop treatment options. However, due to limited data, certain aspects must rely on heuristics, especially at the simulation’s distal ends. In the literature, Murray’s Law is [...] Read more.
Hemodynamic simulations are increasingly used to study vascular diseases such as Intracranial Aneurysms (IA) and to further develop treatment options. However, due to limited data, certain aspects must rely on heuristics, especially at the simulation’s distal ends. In the literature, Murray’s Law is often used to model the outflow split based on vessel cross-section area; however, this poses challenges for the communicating arteries in the Circle of Willis (CoW). In this study, we contribute by assessing the impact of Murray’s Law in patient-specific geometries featuring IA at the posterior communication. We simulate different domain extensions representing common modelling choices and establish Full CoW simulations as a baseline to evaluate the effect of these modelling assumptions on hemodynamic indicators, focusing on IA growth and rupture-related factors such as the Wall Shear Stress (WSS) and Oscillatory Shear Index (OSI). Our findings reveal qualitative alterations in hemodynamics when not modeling posterior communication. Comparisons between computing the anterior circulation and computing the whole Circle of Willis reveal that quantitative changes in WSS may reach up to 80%, highlighting the significance of modelling choices in assessing IA risks and treatment strategies. Full article
(This article belongs to the Special Issue Image-Based Computational and Experimental Biomedical Flows)
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16 pages, 3028 KiB  
Article
An Update on the Superior Cerebellar Artery Origin Type
by Ana-Maria Davidoiu, Mihai Lazăr, Alexandra Diana Vrapciu, Petrinel Mugurel Rădoi, Corneliu Toader and Mugurel Constantin Rusu
Medicina 2023, 59(12), 2164; https://doi.org/10.3390/medicina59122164 - 13 Dec 2023
Cited by 12 | Viewed by 2130
Abstract
Background and Objectives: The microanatomy of the superior cerebellar artery (SCA) is clinically significant. We, thus, aimed at patterning unilateral and bilateral possibilities of SCA origin. Materials and Methods: In total, 205 archived records of computed tomography and magnetic resonance angiograms were used. [...] Read more.
Background and Objectives: The microanatomy of the superior cerebellar artery (SCA) is clinically significant. We, thus, aimed at patterning unilateral and bilateral possibilities of SCA origin. Materials and Methods: In total, 205 archived records of computed tomography and magnetic resonance angiograms were used. There were defined types of SCA origin from the basilar artery (BA): “0”—absent SCA, “1”—preterminal, “2”—collateral SCA, with SCA appearing as a terminal branch of BA, and “3”—SCA from the posterior cerebral artery (PCA) of the cerebral type. Fenestrations and duplications of SCA were recorded. Bilateral combinations of types were recorded as follows: A (1 + 0), B (1 + 1), C (1 + 2), D (1 + 3), E (1 + duplicated SCA), F (2 + 2), G (2 + 3), H (3 + 3), I (3 + duplicated SCA), J (1 + fenestrated SCA). Results: Type 0 SCAs were found in 0.25%, type 1 in 71.29%, type 2 in 19.06%, and type 3 in 9.41%. Absent and fenestrated SCAs were each found in a single case. The most frequent combinations were B (58.05%), C (13.17%) and F (13.17%). Bilateral symmetrical types occurred in 70.7% of cases. Fetal types of PCA and the artery of Percheron modified the BA ends. Combinations of C, F, and G changed the BA ends or tips; thus, different subtypes resulted in five BA bifurcation patterns, including five BA trifurcations and one BA quadrifurcation. BA trifurcation was also found in cases with duplicated SCAs. Conclusions: The SCA has various anatomical possibilities of origin and bilateral combinations that are not presented in anatomical lectures. Details on the specific end of the BA should be gathered on a case-by-case basis. Full article
(This article belongs to the Section Neurology)
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