The anterior communicating artery variants: a meta-analysis with a proposed classification system.

Morphological and morphometric variants of the anterior communicating artery (AComA) have been described by multiple studies; however, a complete classification system of all possible morphological variants with their prevalence is lacking. The current systematic review with meta-analysis combines data from different databases, concerning the AComA morphological and morphometric variants (length and diameter). Emphasis was given to the related clinical implications to highlight the clinical value of their knowledge. The typical AComA morphology occurs with a pooled prevalence (PP) of 67.3%, while the PP of atypical AComA is 32.7%. The identified AComA morphological variants (artery's hypoplasia, absence, duplication, triplication, differed shape, fenestration, and the persistence of a median artery of the corpus callosum- MACC) were classified in order of frequency. The commonest presented variants were the AComA hypoplasia (8%) and the anterior cerebral artery (ACA) fusion (5.9%), and the rarest ones were the MACC persistence (2.3%), and the AComA triplication (0.7%). The knowledge of those variants is essential, especially for neurosurgeons operating in the area. Given the high prevalence of AComA aneurysms, an adequate and complete classification of those variants is of utmost importance.

Composition of encephalic arteries and origin of the basilar artery are different between vertebrates.

Intracranial arterial anatomy is lacking for most mammalian and non-mammalian model species, especially concerning the origin of the basilar artery (BA). Enhancing the knowledge of this anatomy can improve animal models and help understanding anatomical variations in humans. We have studied encephalic arteries in three different species of birds and eight different species of mammals using formalin-fixed brains injected with arterial red latex. Our results and literature analysis indicate that, for all vertebrates, the internal carotid artery (ICA) supplies the brain and divides into two branches: a cranial and a caudal branch. The difference between vertebrates lies in the caudal branch of the ICA. For non-mammalian, the caudal branch is the origin of the BA, and the vertebral artery (VA) is not involved in brain supply. For mammals, the VA supplies encephalic arteries in two different ways. In the first type of organization, mostly found in ungulates, the carotid rete mirabile supplies the encephalic arteries, the caudal branch is the origin of the BA, and the VA is indirectly involved in carotid rete mirabile blood supply. The second type of encephalic artery organization for mammals is the same as in humans. The caudal branch of the ICA serves as the posterior communicating artery, and the BA originates from both VAs. We believe that knowledge of comparative anatomy of encephalic arteries contributes to a better understanding of animal models applicable to surgical or radiological techniques. It improves the understanding of rare encephalic variations that may be present in humans.

Hypoplastic arteries of the cerebral arterial ring in the blind spot of computed tomography angiography.

BACKGROUND: Some variations of the cerebral arterial circle (CAC) are associated with an increased risk for the development of various pathological conditions. This paper aimed to determine the prevalence of hypoplastic arteries of CAC and to emphasize the limited possibility of their visualization by computed tomography angiography (CTA). MATERIALS AND METHODS: The research was performed on 400 adult cadavers by macro- and microdissection of the cerebral arteries. Each case was photographed and the diameter of the arteries was measured digitally, by analyzing photographs of the bases of the brain in the ImageJ program. RESULTS: The largest prevalence of artery diameter <1mm (<0.6mm) in CAC had the posterior communicating artery (PCoA). PCoA on the left side was hypoplastic in 44.9% (11.4%) of cases, while the same artery on the right side was hypoplastic in 44.3% (6.6%) of cases. The posterior cerebral artery was hypoplastic on the left side in 3% (0.6%) and on the right side in 4.2% (0.6%) of cases. The anterior cerebral artery had a hypoplastic caliber only on the right side in 2.4% (0.6%) of the cases, while the internal carotid arteries did not have a diameter <1mm in any case. The anterior communicating artery showed the greatest variability in morphology. Studies on CTA describe the occurrence of aplasia in a statistically significantly higher percentage, and the occurrence of hypoplastic arteries in a statistically significantly lower percentage compared to studies on cadavers. CONCLUSIONS: Due to significant differences between cadaveric and radiological studies, it is necessary to analyze their results regarding arterial hypoplasia and aplasia separately. A diameter of less than 1 mm has been suggested as a criterion for arterial hypoplasia.

Anatomical Variations and Clinical Significance of the Cerebral Arterial Circle in Turkish Cadavers / Variaciones Anatómicas y Significancia Clínica del Círculo Arterial Cerebral en Cadáveres Turcos

SUMMARY: The structure formed by the arteries, which is of great importance in the irrigation of the brain, is called the cerebral arterial circle (Polygon of Willis). Since the cerebral arterial circle provides brain nutrition, vascularabnormalities in this region are highly relevant. Therefore, the aim of our study was to examine the variations of the cerebral arterial circle in cadavers of Turkish individuals. In our study, 32 human cadavers obtained from three different universities were retrospectively examined. Brain tissue obtained from cadavers by craniotomy was kept in 20 % formaldehyde solution for an average of 10 days for fixation. Cerebral arterial circle diagrams were determined in all cadavers by staining and photographs were taken. As a result of the brain examinations, a variation of the cerebral arterial circle was detected in 24/32 brains. Vascular variations have an important place in congenital variations. For this reason, we believe that our brain study will contribute to clinical studies on this topic by investigating variations of the cerebral arterial circle.

La estructura formada por las arterias que tiene una gran importancia en la irrigación del cerebro se denomina círculo arterial cerebral (Polígono de Willis). Dado que el círculo arterial cerebral proporciona la irrigación cerebral, las anomalías vasculares en esta región son muy relevantes. Por lo tanto, el objetivo de nuestro estudio fue examinar las variaciones del círculo arterial cerebral en cadáveres de individuos turcos. En nuestro estudio, se examinaron retrospectivamente 32 cadáveres humanos obtenidos de tres universidades diferentes. El tejido cerebral de los cadáveres fue obtenido por craneotomía y se mantuvo en solución de formaldehído al 20 %, durante 10 días en promedio para su fijación. Se determinaron los diagramas de círculo arterial cerebral en todos los cadáveres mediante coloración y se tomaron fotografías. Como resultado de los exámenes, se detectó una variación del círculo arterial cerebral en 24/32 de los cerebros. Las variaciones vasculares tienen un lugar importante en las variaciones congénitas. Por esta razón, creemos que nuestro estudio contribuirá a estudios clínicos sobre el tema al pesquisar las variaciones del círculo arterial cerebral.

Association between flow patterns of the posterior cerebral arterial circle and basilar-tip aneurysms.

PURPOSE: The Cerebral arterial circle presents multiple individual anatomical configurations which are of the highest importance regarding the pathological processes for intracranial aneurysms development. Previous studies highlighted the importance of geometry and especially arterial bifurcations leading to aneurysms development. The primary objective of this study was to determine whether a flow pattern asymmetry of the P1 segments of the posterior cerebral arteries was associated with a higher risk of basilar tip aneurysm. MATERIAL AND METHODS: Two different populations were retrospectively reviewed. The first population, without aneurysm, for which TOF MRI sequences were reviewed. The second population with patients harboring basilar tip aneurysms for whom cerebral angiograms were reviewed. We retrospectively analyzed the flow contribution and symmetry of the two right and left P1 segments of the posterior cerebral arteries and the two posterior communicating arteries (Pcomm). We analyzed the association and risk factors for basilar tip aneurysm. RESULTS: The anatomical and flow configurations of P1 and Pcomm have been reviewed in 467 patients without aneurysms and 35 patients with aneurysms. We identified a significant association between the flow pattern asymmetry of the P1 segments and the presence of a basilar tip aneurysm (OR = 2.12; IC95% = [1.01-4.36]; p = 0.04). We also confirmed that the male gender was protective against aneurysm (OR = 0.45; IC95% = [0.194-0.961]; p = 0.04). CONCLUSION: Non-modal basilar tip bifurcation and flow asymmetry of P1 segments are associated with an increased risk of basilar tip aneurysm. These findings highlight the importance of analyzing MRI-TOF of the posterior configuration of the Cerebral arterial circle to potentially refine the aneurysms risk prediction.

Duplication of the internal carotid artery and segmental aplasia of the vertebral arteries.

The internal carotid artery mainly supplies the brain. As the internal carotid artery contributes to the formation of the cerebral arterial circle, its variations are relevant in imaging, interventional radiology, and surgery. Knowledge of these variations is important for vascular anastomosis in free flap reconstruction and in arterial ligatures for haemostasis. During a cadaveric cervical dissection, a duplicated left internal carotid artery was incidentally observed in the carotid triangle of the neck. The internal carotid branches were dissected up to their distribution to the brain. The two branches of the left internal carotid artery penetrated into the base of the skull by the carotid canal and the foramen magnum, respectively. With the right internal carotid artery, they formed the cerebral arterial circle. The basilar artery was formed by the branch of the left internal carotid artery entering the skull by the foramen magnum. The right internal carotid artery and the two branches of the left internal carotid gave rise to all of the arteries of the cerebral arterial circle. The vertebral arteries did not contribute to its formation. This duplication of the internal carotid arteries is rare, as the literature does not describe any case of vertebral artery aplasia replaced by an internal carotid artery.

Variations of the cerebral arterial circle: morphological and clinical analysis / Variaciones del círculo arterial cerebral: análisis morfológico y clínico

SUMMARY: The variations knowledge of the cerebral arterial circle (CAC) is relevant due to its influence on the development of ischemic encephalic disorders. Among these variations, when the external diameter of the posterior communicating artery exceeds the posterior cerebral artery caliber, we have a fetal conformation of this circle. The aim of this study was to describe the variations of the CAC in Chilean individuals and to know the type of arterial conformation. Thirty adult brains were used to measure lengths and caliber of the pre-communicating segments of the anterior (A1) and posterior (P1) cerebral arteries, and the anterior (ACoA) and posterior (PCoA) communicating arteries. The arterial conformation type was established, and the length and caliber of these vessels were compared according to the right or left side. It was observed that 76.6 % of the CACs presented aplasia and / or hypoplasia. Of its components, PCoA was hypoplasic in 53.3 %, appearing bilaterally in 40 % of the subjects. The comparison according to the side, indicated that the mean length of A1 and PCoA on the right side was slightly higher. In the case of caliber, the mean of A1, P1 and PCoA was higher on the left side. Regarding P1 and PcoA caliber, 33 % of the CACs presented unilateral fetal conformation. Regardless of the variability presented by the CAC, there is consensus that PCoA exhibits the greatest variability. The understanding of this variability requires an analysis of the embryonic aspects that can explain the fetal conformation of the CAC in the adult.

RESUMEN: El conocimiento de las variaciones del círculo arterial cerebral (CAC) resultan relevantes por su influencia en el desarrollo de trastornos isquémicos encefálicos. De estas variaciones, los cambios del calibre de la arteria comunicante posterior (ACoP) determinan una conformación fetal de este círculo. El objetivo de este estudio fue describir las variaciones del CAC en individuos chilenos y conocer el tipo de conformación arterial. Se utilizaron 30 encéfalos adultos a los que se midieron las longitudes y calibres de los segmentos precomunicante de las arterias cerebrales anteriores (A1) y posteriores (P1), y de las arterias comunicante anterior (ACoA) y ACoP. Se estableció el tipo de conformación arterial y se comparó la longitud y calibre de estos vasos según lateralidad. Se observó que el 76,6 % de los CAC presentaron agenesias y/o hipoplasias. De sus componentes, la ACoP fue hipoplásica en el 53,3 %, presentándose bilateral en el 40 %. La comparación según lateralidad indicó que la longitud media de A1 y ACoP del lado derecho fueron levemente superiores. En el caso de los calibres, la media de A1, P1 y ACoP fue superior en el lado izquierdo. Respecto de los calibres de P1 y ACoP, el 33 % de los CAC presentaron conformación fetal unilateral. Independientemente de la variabilidad que presenta el CAC, existe consenso de que la ACoP exhibe la mayor variabilidad. La comprensión de esta variabilidad requiere un análisis de los aspectos embrionarios que pueden explicar la conformación fetal de esté círculo arterial en el adulto.

Collateral flow at circle of Willis in healthy condition.

Experimental simulation of cerebrovascular system would be very beneficial tool to evaluate millions of human body cascade sequence. The Circle of Willis (CoW) recently named Cerebral Arterial Circle (CAC) is a main loop structure of cerebral circulatory system which positioned at the cranium base. In this research, we investigate cerebral artery flow pattern in cerebral arteries including afferent, Willisian, and efferent arteries of CAC emphasizing on communicating and connecting arteries which are main routes in CAC and as a risky sites when autoregulation is occurred in terminal parts of middle cerebral arteries (MCAs) by PMMA (Polymethyl methacrylate) chip and high quality camera which depict Sequential images. This novelty study analyze flow pattern in CAC that have been challenging subject area for many years which have investigated by scientists yet, because flow pattern in CAC indicate complication progression. This research tries to construct new platform in cerebral circulation analyzing method by reliable experimental in-vitro approach. The outcomes of this study demonstrate that communicating arteries especially anterior communicating artery (ACoA) is main artery in CAC flow distribution.

Fetal-type variant of the posterior cerebral artery and concurrent bilateral cerebral infarctions in a Korean male cadaver / Variante de tipo fetal de la arteria cerebral posterior e infartos cerebrales bilaterales concurrentes en un cadáver masculino coreano

SUMMARY: Fetal-type variant of the posterior cerebral artery is a relatively common variant of the cerebral arterial circle (circle of Willis), but concurrent cerebral pathologies have not been well reported. We describe a case of fetal-type variant of the posterior cerebral artery and concurrent bilateral cerebral infarctions in the territories of the middle cerebral artery in a 78-year-old Korean male cadaver. Fetal-type variant of the posterior cerebral artery was found the right cerebral arterial circle, arose from the internal carotid artery with larger diameter than the pre-communicating segment from the basilar artery. Histopathological examination revealed that left supramarginal gyrus and right infraparietal lobule showed characteristic cerebral infarctions with chronological changes, respectively. Knowledge on the variation in the posterior cerebral artery combined with clinical features including cerebral infarction plays a pivotal role to anatomists and clinicians.

RESUMEN: La variante de tipo fetal de la arteria cerebral posterior es una variante relativamente común del círculo arterial cerebral (polígono de Willis) de arterial cerebral, pero las patologías cerebrales concurrentes no han sido bien informadas. Describimos un caso de variante de tipo fetal de la arteria cerebral posterior e infartos cerebrales bilaterales concurrentes en los territorios de la arteria cerebral media en un cadáver masculino coreano de 78 años. La variante de tipo fetal de la arteria cerebral posterior se encontró en la parte de derecha del círculo arterial cerebral, surgido de la arteria carótida interna con mayor diámetro que el segmento precomunicante de la arteria basilar. El examen histopatológico reveló que el giro supramarginal izquierdo y el lóbulo infraparietal derecho mostraban infartos cerebrales característicos con cambios cronológicos, respectivamente. El conocimiento sobre la variación en la arteria cerebral posterior combinado con las características clínicas, incluido el infarto cerebral es fundamental para los anatomistas y los médicos.

Evaluación morfológica y variaciones del circulo arterial cerebral: un estudio con material cadavérico en una muestra de población colombianas / Morphological evaluation and variations of the cerebral arterial circle: a study with cadaveric material in a Colombian population sample

RESUMEN: El círculo arterial cerebral (CAC) mencionado también como polígono de Willis es una red de anastomosis vascular situado en la base del cerebro, constituido por ramas de la arteria carótida interna (ACI) y del sistema vertebro-basilar. Este estudio evaluó la morfología de las arterias que conforman el CAC en una muestra de individuos colombianos. Previa canalización de la ACI y de la arteria vertebral (AV), se perfundió con resina poliéster (palatal 85 % y estireno 15 %) los lechos vasculares del CAC de 70 encéfalos extraídos de cadáveres a quienes se les practicó necropsia en el Instituto de Medicina Legal de Bucaramanga, Colombia. La arteria comunicante anterior (ACoA) se observó en 68 encéfalos (97,1 %), con ausencia en 2 de las muestras (2,9 %); en promedio su diámetro fue de 1,91?1,04 mm y su longitud 2,21?0,97 mm respectivamente. Asimismo, se encontró hipoplasia en 6 muestras (8,4 %). La arteria comunicante posterior (ACoP) estuvo ausente en 2 de las muestras (5,7 %); su longitud fue 11,63?2,12 mm, mientras que su calibre fue de 1,21?0,58 mm, siendo ligeramente mayor en el lado derecho, sin diferencias estadísticamente significativas con relación al lado de presentación (p= 0,763). Se encontró hipoplasia de la ACoP en forma bilateral en 19 de las muestras (27,1 %) y unilateral en 15 muestras (21,4 %). En 8 muestras (20 %) de 35 CAC evaluados se observó configuración fetal. La incidencia de hipoplasia de la ACoP y de configuración fetal encontrados en el presente estudio, se ubican en el segmento superior de lo reportado en la literatura. Estas expresiones morfológicas han sido consideradas como coadyuvantes en el desarrollo de accidentes cerebro-vasculares (ACV).

SUMMARY: The cerebral arterial circle (CAC), also referred to as the polygon of Willis is a network of vascular anastomoses located at the base of the brain, consisting of branches of the internal carotid artery (ICA) and the vertebrobasilar system (VBS). This study evaluated the morphology of the arteries forming the CAC in a sample of Colombian individuals. After cannulation of the ICA and the vertebral artery (VA), the vascular beds of the ACC of 70 brains extracted from cadavers at the Institute of Legal Medicine of Bucaramanga, Colombia, were perfused with polyester resin (85 % palatal and 15 % styrene). The anterior communicating artery (ACoA) was observed in 68 brains (97.1 %), with absence in 2 of the samples (2.9 %); on average its diameter was 1.91?1.04mm and its length 2.21?0.97mm respectively. Likewise, hypoplasia was found in 6 samples (8.4 %). The posterior communicating artery (ACoP) was absent in 2 of the samples (5,7 %); its length was 11.63?2.12mm, while its caliber was 1.21?0.58mm, being slightly larger on the right side, with no statistically significant differences in relation to the side of presentation (p= 0.763). Hypoplasia of the ACoP was found bilaterally in 19 of the samples (27.1 %) and unilaterally in 15 samples (21.4 %). Fetal configuration was observed in 8 samples (20 %) of 35 CACs evaluated. The incidence of ACoP hypoplasia and fetal configuration found in the present study are in the upper segment of those reported in the literature. These morphological expressions have been considered as coadjuvants in the development of cerebrovascular accidents (CVA).

Morphologic variants of the Cerebral Arterial Circle on computed tomographic angiography (CTA): a large retrospective study.

PURPOSE: To confirm and illustrate the great variability of morphology of the Cerebral Arterial Circle (CAC)-also commonly called "Circle of Willis"-in current clinical Computed Tomography Angiography (CTA) practice. METHODS: Computed Tomographic Angiographic 3D Volume Rendering reconstructions of the CAC performed in a series of 511 patients were retrospectively reviewed and classified following their anatomic configuration. RESULTS: An amount of 27 CAC configurations were listed. Complete and "nearly complete" (1 missing segment) CACs were found in 115 (22.58%) and 157 (28.6%) patients. The posterior arch was much more frequently incomplete (374 patients = 73.18%) than the anterior arch (96 patients = 18.4%). The main cause was a high prevalence of missing posterior communicating arteries (PCoAs). The left or right PCoA were unilaterally lacking in 156 patients (30.53%) and both PCoAs were lacking in 179 patients (35.02%). Cases with 2 and 3 missing segments were observed in 184 (36%) and 44 patients (8.6%). Precarious situations were also identified including 7 cases (1.4%) of complete isolation of the middle cerebral artery (MCA), 11 cases (2.15%) of absence of interhemispheric supply, 205 cases (40.1%) of full separation of the carotid and vertebra-basilar (VB) territories and 44 cases (8.6%) of full separation of the three main arterial axes (both ICAs and VB). The prevalence of Fetal Posterior Cerebral Arteries (FPCA) variants was also reported. A "Full" FPCA was found unilaterally in 48 (9.4%) and bilaterally in 13 (2.54%) of patients. Apart from agenesis and hypoplasia reported in our study, various other variations of the anterior complex of the CAC (ACoA and A2 segments of the ACA) were also noted. CONCLUSION: CTA with 3D Volume Rendering may powerfully assess the numerous variations of the CAC. This assessment is of prime importance for the evaluation of patients presenting with risk factors or in whom neurosurgery, cardiac surgery, interventional radiology or carotid endarterectomy (CEA) are being considered.

Anatomical variations of the circle of Willis and their prevalence, with a focus on the posterior communicating artery: A literature review and meta-analysis.

The circle of Willis is an anastomotic network of arteries surrounding the base of the brain, providing collateral circulation to prevent ischemia. It has, however, long been established that it exhibits considerable anatomical variation when compared to Thomas Willis' originally described circle. This study aimed primarily to determine an accurate prevalence of the variation of the circle of Willis in the general population and the prevalence of common posterior communicating artery variations. Additional aims were to explain why such a wide range of reported variations exist, and whether different types of studies report significantly different prevalence of variation. A comprehensive literature search identified 764 papers. A three-phase screening process was undertaken, involving a critical analysis of papers, and a total of 33 papers were selected for analysis and literature review. A descriptive statistics test with bootstrap was performed to estimate the average prevalence of variations. The estimated prevalence of general variation, unilateral, and bilateral posterior communicating artery hypoplasia or aplasia was 68.22 ± 14.32%, 19.45 ± 8.63%, and 22.83 ± 14.58%, respectively. Over half of the population exhibit a circle of Willis with some form of variation. To provide a more accurate estimation for the prevalence of variations, a universal classification system needs to be established, collating all the work from high-quality studies, to provide a comprehensive database of the circle's variations. Knowing the prevalence of variations and how they can impact neurosurgical approaches or patterns of ischemic pathology can be crucial in providing effective patient care.

Variantes anatómicas del círculo arterial cerebral en un anfiteatro universitario en Bogotá (Colombia) / Anatomical Variations of Arterial Cerebral Circle in an Amphitheater of a University in Bogotá, Colombia / Variantes anatômicas do círculo arterial cerebral em um anfiteatro universitário em Bogotá, Colômbia

Resumen Introducción: el cerebro es un órgano altamente irrigado, y esta irrigación es suministrada por el círculo arterial cerebral: una red arterial anastomótica con frecuentes variaciones anatómicas, algunas asociadas con patologías. El objetivo es describir las características antropométricas y variaciones anatómicas del círculo arterial cerebral en una muestra de especímenes cadavéricos humanos. Materiales y métodos: se revisaron 50 encéfalos, de los cuales 24 cumplieron con los criterios de inclusión. Se realizaron medidas de diámetro y longitud y también se describieron variaciones anatómicas y variaciones morfométricas. Resultados: siete especímenes evidenciaron variaciones anatómicas (29.1 %); 3 (12.5 %), arteria cerebral anterior (ACA) ácigos; uno (4.1 %), doble ACA en el segmento A1; uno (4.1 %), triple ACA en el segmento A2 y doble arteria comunicante anterior (AcomA); uno (4.1 %), agenesia de la arteria comunicante posterior (AComP) derecha; uno (4.1 %), de la AComP izquierda. El 29.1 % presentó variaciones antropométricas; el 12.5 %, hipoplasia de la AComP derecha; el 12.5 %>, de la AComP izquierda, y el 4.1 %>, hipoplasia bilateral de la AComP. Conclusión: la presencia de variaciones anatómicas fue inferior a la hallada en otros estudios, con predominio de variantes de la circulación anterior. Se describe la presencia de triple ACA en el segmento A2 y doble arteria comunicante anterior.

Abstract Introduction: The brain is a highly irrigated organ; this irrigation is supplied by the cerebral arterial circle: an anastomotic arterial network with frequent anatomical variations, some of which are associated with pathologies. This study aimed to describe the anthropometric characteristics and anatomical variations of the cerebral arterial circle in a sample of human cadaveric specimens. Materials and Methods: A total of 50 brains were examined, 24 of which met the inclusion criteria. Diameter and length measurements were obtained, and anatomical and morphometric variations were described. Results: Seven specimens (29.1%) had anatomical variations: 3 (12.5%) had azygos anterior cerebral artery (ACA), 1 (4.1%) had double ACA in segment A1, 1 (4.1%) had triple ACA in segment A2 and double anterior communicating artery (AcomA), 1 (4.1%) had right posterior communicating artery (AComP) agenesis, and 1 (4.1%) had left AComP agenesis. Seven specimens (29.1%) had anthropometric variations: 3 (12.5%) had hypoplasia of right AComP and 3 (12.5%) of left AComP and 1 (4.1%) had bilateral hypoplasia of AComP. Conclusion: The presence of ana-tomical variations was lower than that reported in other studies, with a predominance of variations of the anterior circulation. The presence of triple ACA in segment A2 and double AcomA was described.

Resumo Introdução: o cérebro é um órgão altamente irrigado; esta irrigação é fornecida pelo círculo arterial cerebral: uma rede arterial anastomótica com frequentes variações anatómicas, algumas associadas a patologias. O objetivo é escrever as características antropométricas e variações anatômicas do círculo arterial cerebral em uma amostra de espécimenes cadavéricos humanos. Materiais e métodos: se revisaram 50 encéfalos dos quais 24 cumpriram os critérios de inclusão; realizaram-se medidas de diâmetro e longitude, descreveram-se variações anatômicas e variações morfométricas. Resultados: o 29,1% dos espécimenes apresentaram variações anatómicas (n = 7 ), 3 (12,5%) apresentaram artéria cerebral anterior (ACA) ázigos, um (4,1%) apresentou dupla ACA no segmento A1, um (4,1%) apresentou triple ACA no segmento A2 e dupla artéria comunicante anterior (AcomA), um (4,1%) apresentou agenesia da artéria comunicante posterior (AComP) direita, um (4,1%) da AComP esquerda. 29,1% apresentaram variações antropométricas, três (12,5%) apresentaram hipoplasia de AComP direita, três (12,5%) da AComP esquerda e um (4,1%) hipoplasia bilateral da AComP. Conclusão: a presença de variações anatómicas foi inferior à reportada em outros estudos, com predomínio de variantes da circulação anterior, se descreve a presença de triple ACA no segmento A2 e dupla artéria comunicante anterior.

Morphometric evaluation of Anterior Cerebral Artery (on Digital Subtraction Angiography)-Potential implications.

PURPOSE: The aim of the present study was to perform a morphometric analysis of ACA and to establish significant differences, if any, with sex and age via Digital Subtraction Angiography (DSA). METHODS: This cross-sectional study was conducted on 70 patients (>20 years) for the evaluation of ACA by Digital Subtraction Angiography done on a Philips biplane system clarity (Allura FD20/20). Length and diameter of ACA were taken manually on the DSA console using auto-calibration. Statistical analysis was done. RESULT: Mean diameter and length of ACA was found to be greater in female. The f-ratio value for diameter and length of the same was 1.43 and 0.92 respectively. The length of ACA was found to be statistically significant for different age groups. The mean length of ACA followed a decreasing trend with age, whereas mean diameter of ACA was nearly the same in all the age groups. CONCLUSION: The results of our study show that the length of ACA was found to be statistically significant for different age groups.

Morphological configuration and topography of the brain arterial supply of the one-humped camel ( Camelus dromedarius, Linnaeus 1758) / Configuración morfológica y topografía del suministro arterial del encéfalo del camello de una joroba ( Camelus dromedarius, Linnaeus 1758)

This study investigated the anatomy of the arteries of the brain, including the arterial circle of the brain, its branches and junctions, in five camel (Camelus dromedarius, Linnaeus 1758) following intravascular injection of colored latex via common carotid artery. The course and distribution of the arterial supply to the brain was described and morphological analysis was made. The basilar artery contributed to the blood supply of the brain in the camel in contrast to the situation in other Artiodactyla order.

En presente estudio se analizó la anatomía de las arterias del encéfalo en cinco camellos (Camelus dromedarius, Linnaeus 1758). Después de administrar una inyección intravascular de látex coloreado en la arteria carótida común se estudiaron las arterias incluyendo al círculo arterial del cerebro, sus ramas y uniones. Fueron descritos en detalle el curso y la distribución del suministro arterial al encéfalo y se realizó un análisis morfológico. La arteria basilar contribuyó al suministro de sangre del encéfalo del camello, diferenciando este aspecto en otras especies de Artiodactyla.

Anatomical variants of anterior cerebral arterial circle: a study by multidetector computerized 3D tomographic angiography / Variantes anatómicas de la región anterior del circulo arterial cerebral: estudio por angiotomografía computarizada 3D

One of the most common causes of stroke is rupture of aneurysms whose approach requires knowledge of anatomical variants. The aim of this study was to determine the prevalence of anatomical variants of the anterior cerebral artery (ACA) and the anterior communicating artery (AComA) by 3D computed tomography angiography (3D CTA) in Mexican individuals. A retrospective, observational, cross-sectional descriptive study of 283 patients, independent of sex or age, in which morphometric measurements of cerebral vessels were evaluated using contrasted 3D CTA from a period of two years was performed. We found at least one "atypical" variant in a third of the study population (33.93 %). The most common "atypical" variant was the absence of the AComA (14.1 %). A significant association between the hypoplastic variant of the right A1 segment and hypoplasia of the left A1 and the right A2 was found, while hypoplasia of the left A1 was associated with hypoplasia of the right A2. There is a difference in the prevalence of anatomical variants of the ACA-AComA complex in Mexican population in relation to other populations. The typical variant is the most prevalent form in the study population. However, the presence of atypical variants represents an important number that should be taken into account in clinical and surgical procedures.

Una de las causas más frecuentes de accidente cerebrovascular es la ruptura de aneurismas cuyo abordaje requiere el conocimiento de las variantes anatómicas. El presente estudio tuvo como objetivo determinar la prevalencia de variantes anatómicas de la Arteria Cerebral Anterior (ACA) y la Arteria Comunicante Anterior (AComA) mediante angiotomografías computarizadas 3D (angioTAC 3D) de individuos mexicanos. Se realizó un estudio retrospectivo, observacional, transversal y descriptivo en el que se evaluaron angioTAC contrastados con reconstrucción 3D de 283 pacientes, sin considerar género ni edad, obtenidas durante un periodo de dos años a los que se les realizaron mediciones morfométricas en los vasos de interés. Se encontró al menos una variante "atípica" en un tercio de la población estudiada (33,93 %). La variante "atípica" más común fue la ausencia de AComA (14,1 %). Se encontró asociación significativa entre la variante hipoplásica del segmento A1 derecha y la hipoplasia de A1 izquierda y A2 derecha; mientras que la hipoplasia de A1 izquierda se asoció a la variante hipoplasia de A2 derecha, encontrándose mayor tendencia de aparición de aneurismas en función del menor diámetro del segmento A2 derecho de la ACA. Existe diferencia en la prevalencia de variantes anatómicas del complejo ACA-AComA en población mexicana con respecto a otras poblaciones. La variante típica constituye la forma más prevalente en la población estudiada. Sin embargo, la presencia de variantes atípicas representa una cifra importante que deberá tomarse en cuenta en procedimientos clínicos y quirúrgicos.

Fenestrations and Various Duplications of the Posterior Communicating Artery in the Prenatal and Postnatal Periods.

BACKGROUND: The 2 paired arteries-the posterior communicating arteries (PCoAs) and the precommunicating parts of the posterior cerebral arteries-form the so-called posterior segment of the cerebral arterial circle on the base of the brain. A number of (ab)normal morphologic features were described in the literature (e.g., unusual kinking, or extreme elongations, hypoplasia, duplications, fenestrations, the infundibular widening, or aplasia of the PCoA in the prenatal and/or postnatal periods). The aim of this study was to analyze an incidence of various fenestrations and duplications of the PCoA, and describe their general features and their association with other vascular abnormalities. METHODS: The research was performed on the brains of 200 human fetuses and 377 adult cadavers of both genders and different ages using microdissection and macrodissection methods. RESULTS: There were 0.34% cases with PCoA fenestrations and 3.12% cases with various PCoA duplications. Their morphologic features were described and compared with the similar PCoA abnormalities recorded in the scientific literature. There was no association between the PCoA and either duplication or aneurysm in adult cases. CONCLUSIONS: After thorough examination, the fenestrations and duplications of the PCoA are distinguished as 2 special forms of vascular abnormalities, and the PCoA duplications are characterized as partial and total. Furthermore, whereas the low incidence of a fenestration of the PCoA suggests it to be a sufficiently rare phenomenon, the duplications of the PCoA trunk are fairly frequent, especially concerning its terminal segment.

Association of migraine headaches with anatomical variations of the Circle of Willis: Evidence from a meta-analysis.

BACKGROUND: Several studies have attempted to investigate whether variations in the Circle of Willis (COW) are more common in migraine patients and whether the subsequent changes in perfusion may contribute to the pathomechanism of migraine. However, studies are not in agreement as to whether or not there is an increased prevalence of COW variations in migraineurs. OBJECTIVE: To determine if migraine headaches are associated with variations in morphology of the COW. METHODS: A systemic search of the major electronic databases was performed for articles studying the association of variations in the COW and migraine. Data on the prevalence of variations in patients with migraine were extracted and pooled into the meta-analysis. RESULTS: A total of four articles (n=807 patients) were deemed eligible for the meta-analysis. Migraine, regardless of subtype, was found to be associated with variations in the COW (OR=2.27, 95%CI 1.53-3.38, p<0.0001). An incomplete posterior circle (OR=2.60, 95%CI 1.79-3.76, p<0.00001) was found to be more strongly associated with migraine than an incomplete anterior circle (OR=2.01, 95%CI 1.15-3.53, p=0.01). In sub-group analysis, migraine with aura was found to be associated with both an incomplete posterior (OR=3.55, 95%CI 2.25-5.59, p<0.00001) and an incomplete anterior circle (OR=2.35, 95%CI 1.20-4.62, p=0.01). Migraine without aura was found only to be associated with an incomplete posterior circle (OR=2.10, 95%CI 1.39-3.17, p=0.0004). CONCLUSIONS: Migraine is associated with anatomical variations in both the anterior and posterior portions of the COW. However, larger prospective trials are needed to determine the true prevalence of variations and their pathological significance.