Normal Cerebral Arterial Development and Variations

Department of Radiology, Johns Hopkins Hospital, Baltimore, MD 21287, USA.
Seminars in Ultrasound CT and MRI (Impact Factor: 1.2). 06/2011; 32(3):242-51. DOI: 10.1053/j.sult.2011.02.002
Source: PubMed


The cerebral vascular architecture is both unique and heterogeneous in its structure, organization, and function. For many years, it was believed that brain vasculature was dominated by nonanastomosing terminal or "end-arteries." This was primarily based upon the observation of discrete distribution of brain infarcts after embolic occlusion of particular vessels. It was not until the detailed anatomy work of Pfeiffer in 1928 that the new concept of an almost-uninterrupted vascular network of brain vasculature was proposed. Since then, the cerebral vascular anatomy and embryology has been studied in great detail. Its full description is beyond the scope of this article, and our aim is to provide a brief overview of the development of cranial arterial anatomy, with special emphasis on commonly encountered anatomical variations that may have clinical implications. The failure to recognize these can lead to misdiagnosis as well as otherwise-preventable iatrogenic injuries and complications. We describe the proposed underlying embryologic processes, pathology and clinical implications of these variations, including aberrant internal carotid arteries, carotid agenesis and hypoplasia, azygous anterior cerebral arteries, arterial fenestrations, and persistent embryonic vessels.

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    • "Bilateral ACA territory stroke from the occlusion of one vessel is also possible when one vessel is feeding both hemispheres as in the case of an azygos ACA [3] [17]. Despite the frequent association with ACA aneurysm occurring with azygos ACA [8], there has not been significant evidence of increased risk of ischemia or stroke associated with an azygos ACA [17]. The bihemispheric PICA and the azygos ACA present in this patient could have a common phylogenic link. "
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    ABSTRACT: Variations in intracranial vasculature are well known. We report a rare anatomic variation in a patient who underwent cerebral angiography for suspected intracranial aneurysm. Digital subtraction angiography revealed a bihemispheric posterior inferior cerebellar artery (PICA) and an azygous anterior cerebral artery (ACA). There was no evidence of any aneurysm or vascular abnormality. To our knowledge, this is the first reported case of a patient with a common PICA supplying both the cerebellar hemispheres and a common ACA supplying ACA territory bilaterally. It is important for the physician to be aware of these anatomical variations in order to differentiate a normal variant from a pathological condition.
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    • "The adventitia is the outer layer composed of connective tissue, nutrient vessels (vasa vasorum) and autonomic nerves. When the cerebral vessels enter the subarachnoid space their adventitia is made up of leptomeningeal cells [7]. The muscular or middle layer is the thickest because it consists of smooth muscle cells and elastic tissue taking care of the local vasoregulation. "
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