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.

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.

Intracranial arterial spasm in the dog

1970 ◽  
Vol 33 (3) ◽  
pp. 260-269 ◽  
Author(s):  
Robert H. Wilkins ◽  
Philip Levitt
Keyword(s):  
Whole Blood ◽  
Cerebral Arteries ◽  
Canine Model ◽  
Circle Of Willis ◽  
Arterial Spasm ◽  
Arterial Tree ◽  
Content Type ◽  
Fine Print

✓ A chronic canine model for the investigation of intracranial arterial spasm was designed and used to study spasm produced by rapid and slow cisternal injections of fresh or heparinized autogenous whole blood, or serum from incubated autogenous blood. Spasm so produced begins within 10 minutes after the injection and lasts from several hours to days. It affects primarily the major arteries of the circle of Willis, especially the proximal anterior cerebral arteries, and it does not seem to involve the extradural arterial tree.

Surgical manipulation of primate cerebral arteries in established vasospasm

1991 ◽  
Vol 75 (3) ◽  
pp. 425-432 ◽  
Author(s):  
J. Max Findlay ◽  
R. Loch Macdonald ◽  
Bryce K. A. Weir ◽  
Michael G. A. Grace
Keyword(s):  
Cerebral Ischemia ◽  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Content Type ◽  
Increased Risk ◽  
The Right ◽  
Surgical Manipulation ◽  
Fine Print

✓ It is generally believed that surgery in the face of angiographic vasospasm is dangerous due to an increased incidence of postoperative cerebral ischemia. One theory is that arterial narrowing is exacerbated by surgical manipulation of vasospastic vessels during aneurysm dissection and clipping. This theory was tested in a primate model of cerebral vasospasm and the results reported. Six monkeys underwent baseline cerebral angiography, followed by induction of subarachnoid hemorrhage (SAH) on both sides of the circle of Willis. An equal amount of fresh autologous blood clot was placed around each internal carotid, anterior cerebral, and middle cerebral artery. Six days later, angiography was repeated and the right craniectomy was reopened for clot evacuation and surgical manipulation of the right cerebral arteries, including placement of a temporary aneurysm clip on the right middle cerebral artery. The left cerebral arteries were not exposed or manipulated, and served as controls. Twenty-four hours later angiography was repeated, then the animals were killed. Equal and significant vasospasm (> 40% reduction in vessel caliber compared to baseline, p < 0.05) was seen in the middle cerebral arteries on both sides of the circle of Willis in all animals 6 and 7 days after SAH. There was no significant change in the severity of vasospasm on Day 7 compared with Day 6 in the right cerebral arteries. Increased risk of postoperative cerebral ischemia for surgery in the peak vasospasm period may be due to mechanisms other than increased arterial narrowing precipitated by surgical manipulation.

Effects of indomethacin and prostacyclin on isolated human pial arteries contracted by CSF from patients with aneurysmal SAH

1981 ◽  
Vol 55 (6) ◽  
pp. 877-883 ◽  
Author(s):  
Lennart Brandt ◽  
Bengt Ljunggren ◽  
Karl-Erik Andersson ◽  
Bengt Hindfelt ◽  
Tore Uski
Keyword(s):  
Cerebrospinal Fluid ◽  
Arachidonic Acid ◽  
Vessel Wall ◽  
Cerebral Arteries ◽  
Pial Arteries ◽  
Content Type ◽  
Cerebral Vasoconstriction ◽  
Arachidonic Acid Metabolites ◽  
Acid Metabolites ◽  
Fine Print

✓ In small human cerebral arteries preincubated with indomethacin, contractions induced by cerebrospinal fluid (CSF), from patients with subarachnoid hemorrhage were markedly increased. Also contractions induced by noradrenaline, but not 5-hydroxytryptamine, were augmented. Prostacyclin and its metabolite 6-keto-prostaglandin (PG)E1 reversed the contractions induced by CSF, as well as by noradrenaline, 5-hydroxytryptamine, and PGF2α. The findings suggest that these substances are able to counteract the influence of vasoconstrictor material in hemorrhagic CSF. If the capacity to synthesize these “protective” arachidonic acid metabolites is reduced, the resulting imbalance between contractile and relaxant forces acting on the vessel wall may lead to sustained cerebral vasoconstriction.

Arteriovenous malformations in the posterior fossa

1977 ◽  
Vol 47 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Hiroshi Matsumura ◽  
Yasumasa Makita ◽  
Kuniyuki Someda ◽  
Akinori Kondo
Keyword(s):  
Arteriovenous Malformation ◽  
Brain Stem ◽  
Posterior Fossa ◽  
Arteriovenous Malformations ◽  
Cerebellopontine Angle ◽  
Anterior Part ◽  
Content Type ◽  
The Brain ◽  
Fine Print

✓ We have operated on 12 of 14 cases of arteriovenous malformation (AVM) in the posterior fossa since 1968, with one death. The lesions were in the cerebellum in 10 cases (three anteromedial, one central, three lateral, and three posteromedial), and in the cerebellopontine angle in two; in two cases the lesions were directly related to the brain stem. The AVM's in the anterior part of the cerebellum were operated on through a transtentorial occipital approach.

Embolism from intracranial aneurysms

1980 ◽  
Vol 53 (3) ◽  
pp. 300-304 ◽  
Author(s):  
Toshisuke Sakaki ◽  
Kazuhiko Kinugawa ◽  
Tatsuo Tanigake ◽  
Seiji Miyamoto ◽  
Kikuo Kyoi ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Carotid Arteries ◽  
Internal Carotid ◽  
Cerebral Arteries ◽  
Great Care ◽  
Content Type ◽  
Middle Cerebral Arteries ◽  
Internal Carotid Arteries ◽  
Distal Artery ◽  
Fine Print

✓ Embolism from an aneurysm is one of the mechanisms involved in the pathogenesis of ischemic symptoms associated with intracranial aneurysms. Four cases are reported in which aneurysms of the internal carotid arteries and middle cerebral arteries were the source of emboli resulting in cerebral infarction. In the treatment of these aneurysms, it is best to clip the neck of the aneurysm with great care to avoid embolism due to extrusion of clot into the distal artery.

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.

Bifrontal interhemispheric approach to aneurysms of the anterior communicating artery

1986 ◽  
Vol 64 (2) ◽  
pp. 183-190 ◽  
Author(s):  
Jiro Suzuki ◽  
Kazuo Mizoi ◽  
Takashi Yoshimoto
Keyword(s):  
Cerebral Arteries ◽  
Distal Portion ◽  
Anterior Communicating Artery ◽  
Content Type ◽  
Interhemispheric Approach ◽  
Interhemispheric Fissure ◽  
Early Operations ◽  
Temporary Clip ◽  
Fine Print

✓ The authors review their experience with the bifrontal interhemispheric approach in 603 cases of single anterior communicating artery (ACoA) aneurysms and describe the operative technique. With this approach, the olfactory tracts are dissected, and both A1 segments of the anterior cerebral arteries are identified subfrontally. The interhemispheric fissure is then dissected and A2segments are followed from the distal portion toward the ACoA complex. Following the administration of a combination of mannitol, vitamin E, and dexamethasone, a temporary clip is placed on at least the dominant A1 segment prior to dissection of the aneurysm itself. Once the aneurysm has been completely freed from the surrounding structures, the neck is ligated and clipped. If the aneurysm ruptures during surgery, temporary clips are placed on both A1 and A2 segments bilaterally and the operation proceeds in a completely dry field. With this method, it is possible to occlude any of the intracranial vessels for up to 40 minutes within 100 minutes of drug administration. To prevent the possibility of rerupture and the development of vasospasm in the period before aneurysm surgery, the authors have adopted a policy of performing ultra-early operations within 48 hours of the onset of symptoms. Among the 257 cases operated on during the 9 years since 1975, one-fifth have been operated on within 48 hours of rupture, and the in-hospital mortality rate has been only 4.3% (11 cases). Follow-up studies have shown that 87% of the 246 surviving patients have returned to useful lives.

Effects of potassium channel inhibitors on the relaxation induced by the NO donor DEA/NO in isolated human cerebral arteries

2000 ◽  
Vol 93 (6) ◽  
pp. 1048-1054 ◽  
Author(s):  
Ralf G. Hempelmann ◽  
Jörg Seebeck ◽  
Albrecht Ziegler ◽  
H. Maximilian Mehdorn
Keyword(s):  
Cerebral Arteries ◽  
Delayed Rectifier ◽  
Channel Blockers ◽  
Response Curves ◽  
No Donor ◽  
Content Type ◽  
High K ◽  
Relaxant Response ◽  
Small Conductance ◽  
Fine Print

Object. The goal of this study was to investigate whether K+ channels are involved in nitric oxide (NO)—induced relaxation of isolated human cerebral arteries.Methods. Successive concentration—response curves relating to the use of the NO donor diethylamine NO (DEA/NO) were established in the absence and presence of different K+ channel inhibitors after mounting human cerebral arteries onto a wire myograph. The arteries were obtained from macroscopically intact tissue that had been removed during brain tumor operations.A high K+ concentration partially inhibited the relaxant effects of DEA/NO. Different K+ channel inhibitors (tetraethylammonium [TEA], 10−3 M; charybdotoxin, 10−7 M; glibenclamide, 10−6 M; 4-aminopyridine [4-AP], 10−3 M; BaCl2, 5 × 10−5 M; and apamin, 10−6 M) alone failed to affect the responses to DEA/NO. However, a combination of TEA, glibenclamide, 4-AP, and BaCl2 partially blocked the relaxant effects of DEA/NO. In addition, the effects of DEA/NO were inhibited by the thromboxane A2 analog U46619 (3 × 10−7 M).Conclusions. Inhibitors of the large-conductance or small-conductance Ca++-activated K+ channels, the adenosine triphosphate— sensitive K+ channels, and the delayed-rectifier or inward-rectifier K+ channels failed to alter the effects of DEA/NO when only one K+ channel blocker was used. However, a regimen of a combination of K+ channel blockers that possess selectivity for different channels demonstrated that different K+ channel types are involved; these channels may function in a redundant manner and compensate for each other. Selective thromboxane A2 agonists are capable of inhibiting the relaxant response to the NO donor.

Dose responses of cerebral arteries of the dog, rabbit, and man to human hemoglobin in vitro

1980 ◽  
Vol 53 (4) ◽  
pp. 486-490 ◽  
Author(s):  
Glyn R. Wellum ◽  
Thomas W. Irvine ◽  
Nicholas T. Zervas
Keyword(s):  
Cerebral Arteries ◽  
Postmortem Changes ◽  
Human Hemoglobin ◽  
Content Type ◽  
Weak Response ◽  
Basilar Arteries ◽  
Human Arteries ◽  
Dose Responses ◽  
Fine Print

✓ Dose responses in vitro of the basilar arteries of the dog, rabbit, and man to human hemoglobin are reported. For each species, the response occurred over a range of 10−9M to greater than 10−5M hemoglobin. When compared to a maximum serotonin contraction, the relative constriction induced by 10−5M hemoglobin was greater in the rabbit than in the dog, which in turn was greater than in man. The comparatively weak response of the human arteries is probably attributable to postmortem changes.

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