In Mongolian gerbils, bilateral common carotid artery occlusion (BCCAO) for several minutes induces ischemia, due to an incomplete circle of Willis, resulting in delayed neuronal cell death in the Cornet d'Ammon 1 (CA1) region of the hippocampus. Neuronal cell death in the hippocampus and changes in behavior were examined after BCCAO was performed for 5 min in the gerbils. One day after BCCAO, the pyramidal neurons of the CA1 region of the hippocampus showed degenerative changes (clumped chromatin in nuclei). At 5 and 10 days after BCCAO, extensive neuronal cell death was observed in the hippocampal CA1 region. Cognitive performance was evaluated by using the radial maze and passive avoidance tests. In the radial maze test, which examines win-stay performance, the number of errors was significantly higher in ischemic gerbils than in sham-operated gerbils on days 1 and 2 post-operation. In the passive avoidance test, the latency and freezing times were significantly shorter in ischemic gerbils than in sham-operated gerbils on the days 1, 2, and 4–6 post-operation. These results indicate that transient forebrain ischemia impairs cognitive performance, even immediately after the ischemic insult when there are only subtle signs of neuronal cell death.
CA1 Region, Hippocampal ; Carotid Artery, Common ; Cell Death ; Chromatin ; Circle of Willis ; Freezing ; Gerbillinae ; Hippocampus ; Ischemia ; Neurons ; Prosencephalon ; Pyramidal Cells

BACKGROUND AND PURPOSE: The outcomes of acute internal carotid artery (ICA) terminus occlusions are poor. We classified ICA terminus occlusions into 2 groups according to the occlusion pattern of the circle of Willis and hypothesized that clinical outcomes would significantly differ between them. METHODS: Consecutive patients with acute ICA terminus occlusions evaluated by baseline computed tomographic angiography were enrolled. We investigated the occlusion patterns in the circle of Willis, retrospectively classified patients into simple ICA terminus occlusion (STO; with good Willisian collaterals from neighboring cerebral circulation) and complex ICA terminus occlusion (CTO; with one or more of A2 anterior cerebral artery, fetal posterior cerebral artery occlusion, or hypoplastic/absent contralateral A1; or with poor collaterals from anterior communicating artery) groups, and compared their baseline characteristics and outcomes. RESULTS: The STO group (n=58) showed smaller infarct volumes at 72 hours than the CTO group (n=34) (median, 81 mL [interquartile range, 38-192] vs. 414 mL [193-540], P<0.001) and more favorable outcomes (3-month modified Rankin Scale 0-3, 44.8% vs. 8.8%, P<0.001; 3-month mortality, 24.1% vs. 67.6%, P<0.001). In multivariable analyses, STO remained an independent predictor for favorable outcomes (odds ratio 6.1, P=0.010). CONCLUSIONS: Favorable outcomes in STO group suggested that the outcomes of acute ICA terminus occlusions depend on Willisian collateral status. Documenting the subtypes on computed tomographic angiography would help predict patient outcome.
Angiography ; Anterior Cerebral Artery ; Carotid Artery Thrombosis ; Carotid Artery, Internal ; Cerebral Infarction ; Circle of Willis ; Collateral Circulation ; Endovascular Procedures ; Humans ; Mortality ; Posterior Cerebral Artery ; Retrospective Studies

Moyamoya disease (MMD) is a steno-occlusive disease of the cerebral artery around the circle of Willis. It was first described in 1957 in Japan and named because the characteristic appearance of the basal collaterals in cerebral angiography looks like “a puff of smoke” (moyamoya in Japanese). MMD is one of the major causes of stroke in children worldwide, however most common in Korea, Japan and China. In 2011 the ring finger protein 213 gene (RNF213) was identified as a susceptibility gene for MMD. The RNF213 R4810K variant is an Asian founder mutation common to above nations with carrier rates of 0.5-2% of the general population but a 1/150 penetrance of clinical MMD. MMD patients in Korea and Japan harbors RNF213 R4810K variant in 70-90%. In MMD arterial stenosis was found to occur systematically, not only in the intracranial cerebral arteries but also in renal, coronary, pulmonary arteries, suggesting that MMD is a systemic vasculopathy. These extracranial vasculopathy (ECV) is rare but important as a cause of renovascular hypertension, ischemic heart disease, and pulmonary hypertension especially in children with MMD or family members of MMD. Clinical features of ECV will be reviewed in this article.
Asian Continental Ancestry Group ; Cerebral Angiography ; Cerebral Arteries ; Child ; China ; Circle of Willis ; Constriction, Pathologic ; Coronary Vessels ; Fingers ; Humans ; Hypertension, Pulmonary ; Hypertension, Renovascular ; Japan ; Korea ; Moyamoya Disease* ; Myocardial Ischemia ; Penetrance ; Pulmonary Artery ; Renal Artery ; Stroke

BACKGROUND AND PURPOSE: Quantitative magnetic resonance angiography (Q-MRA) enables direct measurement of volume flow rate (VFR) of intracranial arteries. We aimed to evaluate the collateral flows in internal carotid artery (ICA) occlusion with primary collateral pathway via circle of Willis using Q-MRA, and to compare them between patients who recently developed ipsilateral symptomatic ischemia and those who did not. METHODS: Between 2012 and 2014, 505 patients underwent Q-MRA in our institution. Among these, 33 patients who had unilateral ICA occlusion with primary collateral pathway were identified, and grouped into asymptomatic patients, stable patients with chronic infarction, and symptomatic patients with acute/subacute infarction. Mean VFR (mVFR) in intracranial arteries was measured and compared between the patients' groups. Kruskal-Wallis test was used for statistical analysis. RESULTS: Six patients were asymptomatic, fifteen with chronic infarction were stable, and twelve with acute/subacute infarction were symptomatic. The mVFR of ipsilateral middle cerebral artery in symptomatic patients was significantly lower than those in stable or asymptomatic patients (73.7+/-45.6 mL/min vs. 119.9+/-36.1 mL/min vs. 121.8+/-42.0 mL/min; P = 0.04). Total sum of the mVFR of ipsilateral anterior, middle, and posterior cerebral arteries was significantly lower in symptomatic patients than those in other groups (229.3 +/- 51.3 mL/min vs. 282.0+/-68.6 mL/min vs. 314.0+/-44.4 mL/min; P = 0.02). CONCLUSIONS: Q-MRA could be helpful to demonstrate the difference in the degree of primary collateral flow in ICA occlusion between the patients with recent symptomatic ischemia and those without.
Arteries ; Carotid Artery, Internal* ; Circle of Willis ; Collateral Circulation ; Humans ; Infarction ; Ischemia ; Magnetic Resonance Angiography* ; Middle Cerebral Artery ; Posterior Cerebral Artery

The anatomy of the arterial system supplying blood to the brain can influence the development of arterial disease such as aneurysms, dolichoectasia and atherosclerosis. As the arteries supplying blood to the brain develop during embryogenesis, variation in their anatomy may occur and this variation may influence the development of arterial disease. Angiogenesis, which occurs mainly by sprouting of parent arteries, is the first stage at which variations can occur. At day 24 of embryological life, the internal carotid artery is the first artery to form and it provides all the blood required by the primitive brain. As the occipital region, brain stem and cerebellum enlarge; the internal carotid supply becomes insufficient, triggering the development of the posterior circulation. At this stage, the posterior circulation consists of a primitive mesh of arterial networks that originate from projection of penetrators from the distal carotid artery and more proximally from carotid-vertebrobasilar anastomoses. These anastomoses regress when the basilar artery and the vertebral arteries become independent from the internal carotid artery, but their persistence is not uncommon in adults (e.g., persistent trigeminal artery). Other common remnants of embryological development include fenestration or duplication (most commonly of the basilar artery), hypoplasia (typically of the posterior communicating artery) or agenesis (typically of the anterior communicating artery). Learning more about the hemodynamic consequence that these variants may have on the brain territories they supply may help understand better the underlying physiopathology of cerebral arterial remodeling and stroke in patients with these variants.
Adult ; Aneurysm ; Arteries ; Atherosclerosis ; Basilar Artery ; Brain ; Brain Stem ; Carotid Arteries ; Carotid Artery, Internal ; Cerebellum ; Cerebral Arteries ; Circle of Willis ; Embryology* ; Embryonic Development ; Female ; Hemodynamics ; Humans ; Learning ; Parents ; Pregnancy ; Stroke ; Vertebral Artery

Objective: We investigated whether circle of Willis (COW) morphology on 3D time-of-flight (TOF) MR angiography differs between young normal subjects, older normal subjects, and patients with carotid atherosclerotic plaques. Methods: One hundred seventy-seven subjects were grouped according to age into a young group (20 – 40 years; n = 91) and an older group (> 60 years; n = 86). Subjects underwent brain MR examination as part of a health check-up. Fifty-three patients with carotid atherosclerotic plaque were also included for evaluation in this study. COW morphology on 3D TOF MR angiography was analyzed in terms of completeness or incompleteness of the anterior and posterior components of the circle and completeness of the circle. Results: An incomplete pattern of anterior circulation was significantly more common in carotid atherosclerotic plaque patients (20.7%) than normal older subjects (5.5%) (p < 0.01). A complete posterior circulation pattern was more frequent in normal young subjects (46.5%) than in normal older subjects (16.5%) or the patient group (18.9%) (p < 0.01). Of patients with carotid artery stenosis, 18.9% had a bilateral incomplete connection and were significantly more likely to have an incomplete pattern than normal young (2.3%) or normal older subjects (2.2%) (p < 0.001). Conclusion: Young, healthy subjects were significantly more likely to have a complete pattern of posterior circulation than older subjects. Patients with carotid atherosclerotic plaques were significantly more likely to have incomplete anterior circulation and an incomplete circle than young, normal subjects.
Circle of Willis

OBJECTIVE: Cerebral aneurysms (CAs) and abdominal aortic aneurysms (AAAs) are degenerative vascular pathologies that manifest as abnormal dilations of the arterial wall. They arise with different morphologies in different types of blood vessels under different hemodynamic conditions. Although treated as different pathologies, we examine common pathways in their hemodynamic pathogenesis in order to elucidate mechanisms of formation. MATERIALS AND METHODS: A systematic review of the literature was performed. Current concepts on pathogenesis and hemodynamics were collected and compared. RESULTS: CAs arise as saccular dilations on the cerebral arteries of the circle of Willis under high blood flow, high wall shear stress (WSS), and high wall shear stress gradient (WSSG) conditions. AAAs arise as fusiform dilations on the infrarenal aorta under low blood flow, low, oscillating WSS, and high WSSG conditions. While at opposite ends of the WSS spectrum, they share high WSSG, a critical factor in arterial remodeling. This alone may not be enough to initiate aneurysm formation, but may ignite a cascade of downstream events that leads to aneurysm development. Despite differences in morphology and the structure, CAs and AAAs share many histopathological and biomechanical characteristics. Endothelial cell damage, loss of elastin, and smooth muscle cell loss are universal findings in CAs and AAAs. Increased matrix metalloproteinases and other proteinases, reactive oxygen species, and inflammation also contribute to the pathogenesis of both aneurysms. CONCLUSION: Our review revealed similar pathways in seemingly different pathologies. We also highlight the need for cross-disciplinary studies to aid in finding similarities between pathologies.
Aneurysm ; Aorta ; Aortic Aneurysm, Abdominal* ; Blood Vessels ; Cerebral Arteries ; Circle of Willis ; Elastin ; Endothelial Cells ; Hemodynamics* ; Inflammation ; Intracranial Aneurysm ; Matrix Metalloproteinases ; Myocytes, Smooth Muscle ; Pathology ; Peptide Hydrolases ; Reactive Oxygen Species

Moyamoya disease is a cerebrovascular condition that results in the narrowing of the vessels of the circle of Willis and collateral vessel formation at the base of the brain. Although relationships between Graves' disease and cerebrovascular accidents in Moyamoya disease are obscure, the coexistence of the two diseases is noteworthy. Moyamoya disease has been rarely reported in adolescent patients with thyrotoxicosis. Recently, we encountered two adolescent Korean patients with Moyamoya disease associated with Graves' disease who presented with episodic right-sided hemiparesis and syncope. These two girls who had Graves' disease had no history of other diseases or head trauma. A thyroid function test revealed a euthyroid state and a high thyroid-stimulating hormone (TSH) receptor antibody titer at that time. The patients were diagnosed with Moyamoya disease based on brain magnetic resonance angiography and cerebral four-vessel angiography. The patients underwent cranial revascularization by encephalo-duroarterio-synangiosis as soon as a diagnosis was made, which resulted in successful symptom resolution. They fared well and had no additional neurological symptoms as of their last follow-up visits. Here, we report these two cases of confirmed Moyamoya disease complicated by Graves' disease with a review of the literature, and discuss the possible association between the two diseases. To our knowledge, this is the first report in South Korea on Moyamoya disease associated with Graves' disease in adolescents with a euthyroid.
Adolescent* ; Angiography ; Brain ; Circle of Willis ; Craniocerebral Trauma ; Diagnosis ; Female ; Follow-Up Studies ; Graves Disease* ; Humans ; Hyperthyroidism ; Korea ; Magnetic Resonance Angiography ; Moyamoya Disease* ; Paresis ; Stroke ; Syncope ; Thyroid Function Tests ; Thyrotoxicosis ; Thyrotropin

PURPOSE: To evaluate shunt rate and discuss the resultsrelated to selective shunt placement during carotid endarterectomy (CEA) using routine awake test. METHODS: Patients with CEA from 2007 to 2011 were retrospectively reviewed from prospectively collected data. The need for shunt placement was determined by the awake test, based on the alteration in the neurologic examination. We collected data by using the clinical records and imaging studies, and investigated factors related to selective shunt such as collateral circulation and contralateral internal carotid artery (ICA) stenosis. RESULTS: There were 45 CEAs under regional anesthesia with the awake test in 44 patients. The mean age was 61.8 +/- 7.1 years old. There were 82.2% (37/45) of males, and 68.9% (31/45) of symptomatic patients. Selective shunt placement had been performed in only two (4.4%) patients. Among them fewer cases (4%) had severe (stenosis >70%) contralateral ICA lesions, and more cases (91%) of complete morphology of the anterior or posterior circulation in the circle of Willis. There was no perioperative stroke, myocardial infarctionor death, and asymptomatic new brain lesions were detected in 4 patients (9%), including 2 cases of selective shunt placement. CONCLUSION: CEA under routine awake test could besafe and feasible method with low shunt placement rate in selected patients.
Anesthesia, Conduction ; Brain ; Brain Ischemia ; Carotid Artery, Internal ; Circle of Willis ; Collateral Circulation ; Endarterectomy, Carotid ; Humans ; Male ; Monitoring, Intraoperative ; Neurologic Examination ; Prospective Studies ; Retrospective Studies ; Stroke

INTRODUCTIONNourishment for the brain, a highly vascular organ, is derived from a unique structure called the 'circle of Willis', which is formed by the terminal branches of the internal carotid arteries (ICAs) and basilar arteries (BAs). The circle of Willis forms an anastomotic link between the carotid and vertebrobasilar systems in the arterial supply of the brain, while the BA forms an important component of the brain's posterior circulation and supplies its many vital parts.

METHODSA study was performed on 20 brain specimens used for routine dissections at the Anatomy Department, Kasturba Medical College, in order to examine the morphology of BAs in the brain.

RESULTSIn most specimens, the position of the termination of BA was normal, although variations were present in the mode of termination. In one specimen, the BA terminated by dividing into two superior cerebellar arteries. The posterior cerebral arteries (PCAs) arose from ICAs on both sides in this specimen, and a communicating branch was present between the terminal point of the BA and PCA on the left. In another specimen, unilateral variation was seen, with the PCA arising from the ICA on the right and a posterior communicating artery arising from the PCA, connecting it with the BA. The anatomy on the left side was normal.

CONCLUSIONWe highlight the morphological aspects of the BA, the knowledge of which would help neurosurgeons safely diagnose, as well as plan and execute vascular bypass and shunting procedures for the treatment of stenosis, aneurysms and arteriovenous malformations in the posterior cranial fossa.

Basilar Artery ; abnormalities ; anatomy & histology ; Brain ; anatomy & histology ; blood supply ; Cadaver ; Carotid Arteries ; pathology ; Carotid Artery, Internal ; anatomy & histology ; Circle of Willis ; anatomy & histology ; Humans ; Posterior Cerebral Artery ; anatomy & histology