A Uchino

HW Zhao

S Ihara

SB Rooij van

SJ Dimmick

WP Sanders

English

Abdolkarim Rahmanian

Nima Derakhshan

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CASE REPORT Open AccessFenestrated azygos A2 segment: a rareanatomic variationAbdolkarim Rahmanian1 and Nima Derakhshan2*AbstractAdvancement in neurovascular imaging has led to detection of abnormalities and normal anatomic variations. Mostof anatomical variations in cerebral vasculature are asymptomatic and found incidentally; however, some mayincrease the risk of aneurysm formation and subsequent subarachnoid or intracranial hemorrhage. Here in, wereport fenestration within an azygos A2 segment, as an incidental finding, which is an extremely rare anatomicvariation in a patient suffering subarachnoid hemorrhage (SAH). However, there was no correlation found betweenSAH and the mentioned anatomic variation. To author’s knowledge this is the first report of such anatomicvariation with providing source images of brain CT angiograms.BackgroundThe anterior cerebral arteries are devided into fivesegments: A1: from internal carotid artery (ICA) to theanterior communicating artery (A-comA). A2: from the A-comA to the region between genuand rostrum of corpus callosum where it bifurcates. A3: Bifurcation of A2 segment to pericallosal andcallosomarginal which curves around the genu ofcorpus callosum and ends at the rostral part of bodyof corpus callosum. A4 and A5: distal branches on the superior surfaceof corpus callosum with anastomoses to distalbranches of MCA and PCA.Fenestration of intracranial arteries was found on 0.3to 0.9 % of cerebral angiograms, which is more commonin posterior circulation and was claimed to be associatedwith saccular aneurysms. Although fenestration in anter-ior circulation is rare, azygos (unpaired) anterior cerebralartery (ACA) has been described in the literature as ananatomical variant.Here in we report the first case of fenestration withinof an azygos A2 segment of ACA which is an extremelyrare anatomical variation detected in brain computedtomography angiography (CTA).Case presentationA 22-year-old female suffered suddenly onset severeheadache. She had Glasgow coma scale (GCS) of 15/15and her neurologic exam was unremarkable. She wasfound to have subarachnoid hemorrhage (SAH) withinleft sylvian fissure on her brain computed tomography(CT) scan (Fig. 1). So a brain CT angiography with a 16-slice multidetector scan was requested for her, which didnot reveal any vascular lesion justifying SAH within leftsylvian fissure. However we incidentally noticed a fenes-trated azygos A2 segment in coronal images of maximumintensity projections (MIP) of her CTA (Fig. 2a, 2b). Fordetermination of SAH source, she underwent a digital sub-tracted angiography (DSA) of brain 2 weeks later, whichalso did not show any aneurysms. Written consent was ob-tained from the patient to present this report and any im-ages accordingly.DiscussionFenestration of arteries, described as division of arteriallumen into separate channels, each having a uniqueendothelial and muscularis layer, is commonly seen incerebral arteries [1, 2]. Angiographic incidence of arterialfenestration is 0.3 to 0.9 %, and they were thought to bemore common in posterior circulation [1–3]. Howevertwo studies conducted by Van Rooij et al. [4, 5] demon-strated that fenestrations are more common in anterior* Correspondence: nima_med83@yahoo.com2Shiraz Neuroscience Research Center, Department of Neurosurgery, ShirazUniversity of Medical Sciences, Shiraz, IranFull list of author information is available at the end of the article© 2015 Rahmanian and Derakhshan. Open Access This article is distributed under the terms of the Creative CommonsAttribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution,and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a linkto the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedicationwaiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwisestated.Rahmanian and Derakhshan Neurovascular Imaging  (2015) 1:10 DOI 10.1186/s40809-015-0007-9circulation by using the more sensitive diagnostic mo-dality, namely three-dimensional rotational angiography(3DRA). They also found out that 31 % of arterial fenes-trations are associated with an aneurysm.Despite several reviews about fenestrations in posteriorcirculation, the literature lacks sufficient data regardingfenestrations in anterior circulation.Uchino et al. were the pioneers of reviewing anomaliesin anterior circulation by investigation 2000 brain MRangiograms. They found an incidence of 0.3 % for fenes-trations in Middle cerebral artery (MCA) territory,which were all located in M1 segment [6].Anomalies of Anterior cerebral artery including unilat-eral A1 aplasia, triple A2, unpaired or azygos A2 andfenestrations are also uncommon. Unpaired (azygos) A2segment have been recorded in about 2 % and arterialfenestration in about 1.2 % of MR angiograms [7]. Al-though aneurysms have been reported to accompanyunilateral A1 aplasia, triple A2 and azygos A2, no associ-ation was found between fenestrations and aneurysms.Most fenestrations in the territory of anterior cerebralartery are within A1 segment. Data reported from cohortseries of Zhao et al. reviewing cranial MR angiograms, re-vealed quite the same incidence of 0.8 % for fenestrationsin ACA territory and all were detected in A1 segment [8].Uchino et al. reported the first case of fenestration inA2 segment detected in magnetic resonance angiographywhich is the only available report of fenestration in A2segment, which was also recorded in an azygos A2 suchas our case [7].Whether or not this anatomic variation is relatedwith aneurysm formation or SAH is unclear. Howeverto authors’ knowledge this is an exteremely rare reportof such an anatomic variation and might be consideredamong the various normal variations of cerebral arterialanatomy. Unlike previous report of detection of a similaranatomic variation by MRA, we spotted a fenestration inan Azygos A2 segment in brain CTA. Brain CTA is a valu-able adjunct in neurovascular imaging and it can be usedfor assessment of vessels of small caliber.ConclusionAdvancement in neurovascular imaging modalities has ledto a better understanding of cerebrovascular anatomy.Unlike previous report of detection of a similar anatomicvariation by MRA, we spotted a fenestration in an AzygosFig. 1 Axial non-contrasted brain CT scan showing a streak of leftparietal SAHFig. 2 a Coronal view of MIP images of brain CTA showing afenestration at proximal part of an azygos A2 (Arrow). b 3D-Reconstruction of brain CTA from a coronal view highlightingthe site of fenestration within an azygos A2 (Arrow)Rahmanian and Derakhshan Neurovascular Imaging  (2015) 1:10 Page 2 of 3A2 segment in brain CTA. Brain CTA is a valuable adjunctin neurovascular imaging and it can be used for assessmentof vessels of small caliber.Competing interestsThe authors declare that they have no competing interests.Authors’ contributionsAR noted this anomaly and its significance in the literature and revised themanuscript for final submission. ND did the literature review and providedthe manuscript files and figures and obtained informed consent from thepatient. All authors read and approved the final manuscript.Author details1Department of Neurosurgery, Shiraz University of Medical Sciences, Shiraz,Iran. 2Shiraz Neuroscience Research Center, Department of Neurosurgery,Shiraz University of Medical Sciences, Shiraz, Iran.Received: 2 July 2015 Accepted: 15 October 2015References1. Dimmick SJ, Faulder KC. Fenestrated Anterior Cerebral Artery with AssociatedArterial Anomalies: Case Reports and Literature Review. Interv Neuroradiol.2008;14(4):441–5.2. Ihara S, Uemura K, Tsukada A, Yanaka K, Nose T. Aneurysm and fenestrationof the azygos anterior cerebral artery–case report. Neurol Med Chir (Tokyo).2003;43(5):246–9.3. Sanders WP, Sorek PA, Mehta BA. Fenestration of intracranial arteries withspecial attention to associated aneurysms and associated anomalies. Am JNeuroradiol. 1993;14:675–80.4. van Rooij SB, Bechan RS, Peluso JP, Sluzewski M, van Rooij WJ. Fenestrationsof Intracranial Arteries. AJNR Am J Neuroradiol. 2015;36(6):1167–70.5. van Rooij SB, van Rooij WJ, Sluzewski M, Sprengers ME. Fenestrations ofintracranial arteries detected with 3D rotational angiography. AJNR Am JNeuroradiol. 2009;30(7):1347–50.6. Uchino A, Nomiyama K, Takase Y, Egashira R, Kudo S. Fenestration of themiddle cerebral artery detected by MR angiography. Magn Reson Med Sci.2006;5(1):51–5.7. Uchino A, Nomiyama K, Takase Y, Kudo S. Anterior cerebral artery variationsdetected by MR angiography. Neuroradiology. 2006;48:647–52.8. Zhao HW, Fu J, Lu ZL, Lü HJ. Fenestration of the anterior cerebral arterydetected by magnetic resonance angiography. Chin Med J (Engl).2009;122(10):1139–42.Submit your next manuscript to BioMed Centraland take full advantage of: • Convenient online submission• Thorough peer review• No space constraints or color ﬁgure charges• Immediate publication on acceptance• Inclusion in PubMed, CAS, Scopus and Google Scholar• Research which is freely available for redistributionSubmit your manuscript at www.biomedcentral.com/submitRahmanian and Derakhshan Neurovascular Imaging  (2015) 1:10 Page 3 of 3

Neurovascular Imaging

Fenestrated azygos A2 segment: a rare anatomic variation

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Fenestrated azygos A2 segment: a rare anatomic variation

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