A Plastic Model for the Study of Pressure Changes in the Circle of Willis and Major Cerebral Arteries Following Arterial Occlusion

1961 ◽  
Vol 18 (3) ◽  
pp. 361-365 ◽  
Author(s):  
Nurhan Avman ◽  
Edgar A. Bering
Keyword(s):  
Cerebral Arteries ◽  
Arterial Occlusion ◽  
Circle Of Willis ◽  
Plastic Model ◽  
Pressure Changes

scholarly journals Function of Circle of Willis

2014 ◽  
Vol 34 (4) ◽  
pp. 578-584 ◽  
Author(s):  
Zvonimir Vrselja ◽  
Hrvoje Brkic ◽  
Stefan Mrdenovic ◽  
Radivoje Radic ◽  
Goran Curic
Keyword(s):  
Blood Flow ◽  
Pulse Wave ◽  
Cerebral Arteries ◽  
Arterial Occlusion ◽  
Current Theory ◽  
Circle Of Willis ◽  
Arterial Tree ◽  
Passive Pressure ◽  
Flow Pressure ◽  
The Brain

Nearly 400 years ago, Thomas Willis described the arterial ring at the base of the brain (the circle of Willis, CW) and recognized it as a compensatory system in the case of arterial occlusion. This theory is still accepted. We present several arguments that via negativa should discard the compensatory theory. (1) Current theory is anthropocentric; it ignores other species and their analog structures. (2) Arterial pathologies are diseases of old age, appearing after gene propagation. (3) According to the current theory, evolution has foresight. (4) Its commonness among animals indicates that it is probably a convergent evolutionary structure. (5) It was observed that communicating arteries are too small for effective blood flow, and (6) missing or hypoplastic in the majority of the population. We infer that CW, under physiologic conditions, serves as a passive pressure dissipating system; without considerable blood flow, pressure is transferred from the high to low pressure end, the latter being another arterial component of CW. Pressure gradient exists because pulse wave and blood flow arrive into the skull through different cerebral arteries asynchronously, due to arterial tree asymmetry. Therefore, CW and its communicating arteries protect cerebral artery and blood–brain barrier from hemodynamic stress.

Exposure of the anterior part of the circle of Willis in the dog

1974 ◽  
Vol 41 (1) ◽  
pp. 107-112
Author(s):  
Shigeaki Hori ◽  
Williamina A. Himwich
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Content Type ◽  
Anatomical Characteristics ◽  
Fine Print

✓ A technique for exposing the vessels in the anterior part of the circle of Willis in the dog is described. Some of the physiological and anatomical characteristics of the anterior communicating and the anterior cerebral arteries are discussed.

Abstract TMP89: Collaterals and Reperfusion Mediate Blood Pressure Changes in Acute Ischemic Stroke

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
David S Liebeskind ◽  
Graham W Woolf ◽  
Nerses Sanossian ◽  
Jason D Hinman ◽  
Radoslav Raychev ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Endovascular Therapy ◽  
Arterial Occlusion ◽  
Patient Specific ◽  
Pressure Data ◽  
Blood Pressure Data ◽  
Pressure Changes ◽  
Continuous Blood Pressure

Background: The pathophysiology and optimal management of blood pressure changes in acute ischemic stroke remain unknown. Blood pressure guidelines do not consider patient-specific or serial data on dynamic blood pressure readings. We investigated continuous blood pressure data during endovascular therapy for acute stroke to discern changes associated with collaterals, recanalization and reperfusion. Methods: Continuous monitoring blood pressure data was collected in consecutive cases of endovascular therapy for acute ischemic stroke due to ICA or proximal MCA occlusion. Angiography details were independently analyzed to document site of arterial occlusion, baseline collateral grade, time of device deployments, time of recanalization, time of final reperfusion, final AOL recanalization and final TICI reperfusion. Statistical analyses correlated instantaneous and serial blood pressure changes with these angiographic parameters. Results: 80 patients (median age 73 years; 33 women) were studied. Arterial lesions included 37 ICA and 41 proximal M1 MCA occlusions. Collateral grade prior to intervention included 2 ASITN grade 4, 26 grade 3, 23 grade 2, 6 grade 1 and 0 grade 0. oTICI2C reperfusion scores after thrombectomy included 2 TICI 3 (100%), 22 TICI 2C (90-99%), 25 TICI o2B (67-89%), 9 TICI m2B (50-66%), 19 TICI 2A (<50%) and 3 TICI 0/1. More robust collateral grade was associated with greater reperfusion scores (r=0.32, p=0.028). The change in blood pressure (ΔBP) from earliest BP to time of recanalization was mean 59% of ΔBP during the entire procedure. Better collaterals were associated with lower BP prior to recanalization (r=-0.377, p=0.012). Lower BP prior to recanalization was linked with greater TICI reperfusion (r=-0.242, p=0.050). Higher TICI reperfusion scores were also associated with a greater drop or ΔBP at the time of recanalization (r=0.269, p=0.031). AOL recanalization was not related to ΔBP. Conclusions: Collaterals and reperfusion, but not recanalization, mediate blood pressure changes in acute ischemic stroke. Prospective, precision medicine stroke studies should leverage patient-specific, real-time data on continuous blood pressure with imaging correlates to define BP goals of future in-hospital management.

Abstract 389: Gestational Inflammation and Perinatal Arterial Ischemic Stroke: A Causal Connection?

2014 ◽  
Vol 34 (suppl_1) ◽  
Author(s):  
Clemence Guiraut ◽  
Nicole Cauchon ◽  
Martin Lepage ◽  
Guillaume Sebire
Keyword(s):  
Ischemic Stroke ◽  
Cerebral Arteries ◽  
Arterial Occlusion ◽  
Carotid Bifurcation ◽  
Causal Connection ◽  
Arterial Ischemic Stroke ◽  
Motor Impairments ◽  
Perinatal Stroke ◽  
Clinical Model ◽  
Hemiplegic Cerebral Palsy

Introduction: Perinatal arterial ischemic strokes affect about 1/3,000 newborn and are the main cause of hemiplegic cerebral palsy. The large cerebral arteries from the anterior system, namely the intra-cranial carotid bifurcation, are the most affected, ischemic stroke being located in its territory in 85% of cases. The classic, but unproven, pathophysiological hypothesis postulated that arterial occlusion was caused by emboli from placental origin. This remains controversial due to the major unbalance of brain infarcts between anterior and posterior distribution, and to the absence of associated extra-cerebral infarcts. A new pathophysiological perspective emerged from the epidemiological association between gestational inflammation and perinatal stroke. Our hypothesis is that materno-foetal inflammation, induced by gestational exposure to pathogens, leads to a site-specific vasculitis affecting the carotid bifurcation and then triggering a focal thrombosis. Material and methods: Dams were injected with saline or lipopolysaccharide (LPS) from Escherichia coli (200 μg/kg/12h) between gestational day (G) 21 and 22. Brains were harvested at G21, G22 and postnatal day 1 (P1). At P1, a prothrombotic stress (transcutaneous photothrombosis) was applied on middle cerebral arteries to compare its susceptibility to thrombosis between LPS-exposed or unexposed pups. Immunohistochemistry and ELISA detected maternal, placental and fetal/neonatal inflammatory markers. Results: Our results showed a maternal, placental and fetal inflammation mediated by IL-1β, TNF-α and MCP-1 as well as an arterial inflammation in relation with the clinical pattern of perinatal arterial ischemic strokes. LPS+photothrombosis pups presented ischemic strokes and motor impairments, which were not detected when photothrombosis was applied without prior treatment with LPS. Conclusion: Preliminary results from our new pre-clinical model support our hypothesis of increased susceptibility of anterior cerebral arteries to gestational inflammation, and open a new vasculitic pathophysiological avenue to understand perinatal stroke.

scholarly journals Study of variations of the anterior cerebral artery in human brain

2013 ◽  
Vol 02 (03) ◽  
pp. 122-127
Author(s):  
Bishwajeet Saikia ◽  
Kunjalal Talukdar ◽  
Joydev Sarma ◽  
Amitav Sarma ◽  
Sandeep Madaan
Keyword(s):  
Cerebral Artery ◽  
Anterior Cerebral Artery ◽  
Cerebral Arteries ◽  
Initial Step ◽  
Circle Of Willis ◽  
Anatomical Distribution ◽  
Surgical Interventions ◽  
Medical College ◽  
The Individual ◽  
Considerable Individual Variation

Abstract Background and aims: Stroke, the most frequent expression of cerebrovascular disease is one of the leading causes of death and disability throughout the world. The manifestations are largely accounted by the anatomical distribution of the stems and branches of the circle of Willis supplying the brain. Considerable individual variation exists in the pattern and caliber of the individual vessels forming the circle of Willis, which may possibly impair the collateral blood flow. The knowledge of these variations thus, becomes essential for medical as well as surgical interventions. There may possibly be some regional variations in the cerebral arteries not mentioned in standard available texts. Thus, the regional based study of variations present becomes essential. The present study aims to focus on the variation of one of such branches, the anterior cerebral artery (ACA) in the population of Assam, India. Material and Methods: The ACAs of 70 human cadaveric brains were examined by gross dissection in the department of Anatomy and Forensic medicine in Gauhati Medical College. Results: Hypoplastic A-1 segment were found in 7% cases, Hypoplastic A-2 segment in 2.85% cases, Buttonhole formation in 8.57% cases and aneurysmal dilatation in 1.42% cases. The results were compared with that of other authors and variations noted. Conclusion: The present study of ACA using gross dissection is an initial step in providing a reference to the healthcare professionals in the region of Assam. Based on this further studies using newer imaging methods should be carried out to correlate the manifestations clinically.

scholarly journals Average dimensions of the vessels at the base of the brain and the embryological basis of its variations

2013 ◽  
Vol 02 (04) ◽  
pp. 180-189
Author(s):  
Iqbal S.
Keyword(s):  
Anterior Part ◽  
Cerebral Arteries ◽  
Cerebral Dominance ◽  
Circle Of Willis ◽  
Detailed Knowledge ◽  
Differential Growth ◽  
Ischemic Attack ◽  
The Individual ◽  
The Right ◽  
The Brain

Abstract Background and aims: The cerebral circulation is constantly maintained by the anastomotic circle of Willis which is often anomalous in more than 50% of the normal adult brains. These anomalies increase the risk of the stroke and transient ischemic attack in older patients. Adequate blood flow through the circle of Willis is often necessary to prevent these ischemic infarctions. The anomalies of cerebral vessels are directly related to the differential growth of various parts of the brain. A detailed knowledge of the individual measurements of the cerebral arteries is useful to neurosurgeon in planning the shunt operations and in the choice of their patients. The present study is aimed to analyze the average dimensions of the vessels at the base of brain and an attempt to explain the common form of variations in terms of embryological development. Materials and methods: Fifty adult cadaveric brains were obtained from routine cadaveric dissections. The base of the brain with the circle of Willis was fixed in 10% formalin and preserved. The circle was analyzed for variations in the size, length and number of the component vessels and any asymmetry in the configuration. The dimensions of the vessels forming the circle were measured using graduated calipers. The observations were recorded and tabulated. Results: Asymmetry was observed in 10% to 36% of the circles in this study. Anomalies were more common in the posterior than in the anterior part of the circle. The posterior anomalies included hypoplastic vessels, absent vessels and embryonic derivation while anterior anomalies were predominantly of accessory vessels. Middle cerebral artery exhibited the least variations. In majority of the circles, left sided vessels were larger in diameter than the right. Conclusions: Variations are more common in the posterior than in the anterior part of the circle and on the right than on the left side of the brain. There was no correlation between the variations of circle of Willis of the right side and the left cerebral dominance. There seems to be no difference between races, concerning the anatomic variations of the brain circulation.

Bifurcation geometry and the presence of cerebral artery aneurysms

2004 ◽  
Vol 101 (1) ◽  
pp. 108-113 ◽  
Author(s):  
Tor Ingebrigtsen ◽  
Michael K. Morgan ◽  
Ken Faulder ◽  
Linda Ingebrigtsen ◽  
Trygve Sparr ◽  
...  
Keyword(s):  
Cerebral Artery ◽  
Geometric Model ◽  
Cerebral Arteries ◽  
Multivariate Logistic Regression Analysis ◽  
Circle Of Willis ◽  
Parent Vessel ◽  
Content Type ◽  
Optimality Principles ◽  
The Relationship ◽  
Fine Print

Object. The angles of arterial bifurcations are governed by principles of work minimization (optimality principle). This determines the relationship between the angle of a bifurcation and the radii of the vessels. Nevertheless, the model is predicated on an absence of significant communication between these branches. The circle of Willis changes this relationship because the vessels proximal to the ring of vessels have additional factors that determine work minimization compared with more distal branches. This must have an impact on understanding of the relationship between shear stress and aneurysm formation. The authors hypothesized that normal bifurcations of cerebral arteries beyond the circle of Willis would follow optimality principles of minimum work and that the presence of aneurysms would be associated with deviations from optimum bifurcation geometry. Nevertheless, the vessels participating in (or immediately proximal to) the circle of Willis may not follow the geometric model as it is generally applied and this must also be investigated. Methods. One hundred seven bifurcations of the middle cerebral artery (MCA), distal internal carotid artery (ICA), and basilar artery (BA) were studied in 55 patients. The authors analyzed three-dimensional reconstructions of digital subtraction angiography images with respect to vessel radii and bifurcation angles. The junction exponent (that is, a calculated measure of the division of flow at the bifurcation) and the difference between the predicted optimal and observed branch angles were used as measures of deviation from the geometry thought best to minimize work. The mean junction exponent for MCA bifurcations was 2.9 ± 1.2 (mean ± standard deviation [SD]), which is close to the theoretical optimum of 3, but it was significantly smaller (p < 0.001; 1.7 ± 0.8, mean ± SD) for distal ICA bifurcations. In a multilevel multivariate logistic regression analysis, only the observed branch angles were significant independent predictors for the presence of an aneurysm. The odds ratio (OR) (95% confidence interval) for the presence of an aneurysm was 3.46 (1.02–11.74) between the lowest and highest tertile of the observed angle between the parent vessel and the largest branch. The corresponding OR for the smallest branch was 48.06 (9.7–238.2). Conclusions. The bifurcation beyond the circle of Willis (that is, the MCA) closely approximated optimality principles, whereas the bifurcations within the circle of Willis (that is, the distal ICA and BA) did not. This indicates that the confluence of hemodynamic forces plays an important role in the distribution of work at bifurcations within the circle of Willis. In addition, the observed branch angles were predictors for the presence of aneurysms.

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