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Brain & Development 31 (2009) 318–321

Case report

Combination of olfactory course anterior cerebral arteryand accessory middle cerebral artery (MCA) with occluded

in situ MCA and related moyamoya phenomenon

Wei-Che Lin a, Shih-Wei Hsu a,*, Yeh-Lin Kuo a, Joel A. Feekes b, Hung-Chen Wang c

a Department of Diagnostic Radiology, Chang Gung Memorial Hospital – Kaohsiung Medical Center, Chang Gung University College of Medicine,

123 Ta-Pei Road, Naio-Sung County, Kaohsiung 833, Taiwanb Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, NY, USA

c Department of Neurosurgery, Chang Gung Memorial Hospital – Kaohsiung Medical Center, Chang Gung University College of Medicine, Taiwan

Received 18 March 2008; accepted 22 May 2008

Abstract

We describe a rare case of congenital persistence of a primitive olfactory anterior cerebral artery in association with an ipsilateral acces-sory middle cerebral artery. The normally and anatomically positioned, or in situ, middle cerebral artery was occluded. This, along with awell-developed anastomotic network of lenticulostriate artery domains and leptomeningeal collaterals suggested a moyamoya phenom-enon. To our knowledge, ours is the first report of this anatomic variant and the altered conventional vascular territories of supply.� 2008 Elsevier B.V. All rights reserved.

Keywords: Anterior cerebral artery; Primitive olfactory artery; Accessory middle cerebral artery; Moyamoya phenomenon

1. Introduction

Anatomic variations of the anterior cerebral artery(ACA) and the middle cerebral artery (MCA) are rela-tively common and are mentioned in the literature [1].The clinical significance of these alterations has alsobeen reported [2]. The following case involves the uniquecombination of ACA and MCA variants in associationwith a pathologic phenomenon that produced abnormalvascular territories that differ from described deviations.We discuss possible mechanisms for the abnormalities.

2. Case report: a 62-year-old woman

A female patient presented with chronic headachesthat had persisted for more than 1 year. Her headaches

0387-7604/$ - see front matter � 2008 Elsevier B.V. All rights reserved.

doi:10.1016/j.braindev.2008.05.008

* Corresponding author. Tel.: +886 7 7317123x3027; fax: +886 77318762.

E-mail address: hsusw@adm.cgmh.org.tw (S.-W. Hsu).

had recently become increasingly aggravated, with apainful sensation that could not be well localized. CTrevealed a posterior fossa meningioma close to the fora-men magnum. MR imaging (MRI) with MR angiogra-phy (MRA), as well as conventional cerebralangiography, was performed. The patient underwentan operation to resect the meningioma. Her postopera-tive course was uneventful, and she recovered com-pletely. However, her imaging studies had depicted acomplex variation of the circle of Willis.

MRA and conventional angiography revealed ananomalous right ACA. The proximal portion of theright ACA coursed anteriorly and inferomedially, paral-lel to the olfactory tract. After this point, it veered supe-riorly and posteriorly, becoming the normal pericallosalportion of the right ACA. This configuration of theACA indicated a persistent primitive olfactory artery(POA) (black arrow in Fig. 1A and B).

On MRA, the right MCA stemmed from the rightproximal ACA near the junction of the anterior commu-

W.-C. Lin et al. / Brain & Development 31 (2009) 318–321 319

nicating artery (ACoA), and the normal MCA terminalbranches were lacking (white arrow in Fig. 1C). Thisartery was later recognized as an accessory MCA during

Fig. 1. (A) lateral image, (B) frontal image. Angiograms obtained after injectpersistent primitive olfactory artery (POA; black arrow) and occlusion of thmoyamoya phenomenon of the lenticulostriate arteries, which reconstitutesarrowheads) from the anterior choroidal artery (AChA). Leptomeningeal collfrom the ipsilateral fetal-type posterior cerebral artery. (C), MRA reveals anthe ACA near the junction of the anterior communicating artery (ACoA). (Dstemming from the ACoA after injection of the left ICA. Also evident arebranches stemming from the accessory MCA and coursing to the right temppuff-like vessels (white arrowhead) over the base of the right half of the brain.tissue in the right temporal lobe.

angiographic review (white arrow in Fig. 1D). Its bloodflow originated abnormally from the contralateral ICA.The accessory MCA coursed posteriorly and laterally,

ion into the right internal carotid artery (ICA) show a hairpin turn in ae in situ middle cerebral artery (MCA; white blank arrow). Shown isportions of the vascular territories of the perforating arteries (black

aterals (black blank arrow in A) supply part of the right MCA territoryaccessory MCA (white arrow) stemming from the right A1 segment of

) Frontal view reveals opacification of an accessory MCA (white arrow)multiple perforating vessels (white arrowheads) and cortical arterial

oral lobe. (E), Source image from MRA demonstrates multiple minor(F) Axial MRI reveals hypointensity and malacotic change of the brain

320 W.-C. Lin et al. / Brain & Development 31 (2009) 318–321

with an abnormal supply to the territory of the righttemporal lobe provided through multiple small distalbranches. A portion of the perforating arteries enteringthe anterior perforated substance (white arrowhead inFig. 1D) also originated from this accessory MCA.

Minor puff-like vessels (white arrowhead in Fig. 1E)were also seen over the base of the brain. These werebelieved to be due to occlusion of the normal or the insitu MCA (white blank arrow in Fig. 1B) and were sug-gestive of Moyamoya phenomenon. Supporting thisfinding were the abounding branches of the ipsilateralAChA, which were seen reconstituting some of the per-forating vessels (black arrowhead in Fig. 1A and B). Lep-tomeningeal collaterals (black blank arrow in Fig. 1Aand B) from distal branches of the ipsilateral fetal-typeposterior cerebral artery and the persistent POA sup-plied portions of the right MCA territory.

MRI also revealed hypointense lesions with mildencephalomalacotic change of the subcortical tissueover the right temporal lobe. This appearance sug-gested an old insult or hemorrhage (Fig. 1F), whichalso supported the presence of a moyamoyaphenomenon.

3. Discussion

Persistent POA is rarely reported in the literature andis believed to be ACA anomalies [2]. Including the pres-ent example, only 14 cases have been reported, and mostwere associated with saccular aneurysm formations [2].In the embryo, the ACA begins at the formation ofthe secondary branch of the POA [3]. Under normal cir-cumstances, the POA regresses and remains as the recur-rent artery of Heubner. When the ACA arisesabnormally from the distal portion of the POA, theproximal portion of POA remains along the olfactorytract, increasing the distance between the bilateralACAs. A persistent POA in association with a longACoA has been reported in patients missing the recur-rent artery of Heubner [2]. However, the present caseinvolved an interhemispheric POA. The long ACoAwas not seen instead of the regular bilateral ACA A1segment. This finding differed from those of previouslyreported cases. We believe that this is a persistentPOA variant that has not been mentioned in theliterature.

As a persistent POA, an accessory MCA is one ofthree ACA-type variations, and it mainly affects devel-opment of the striatocortical system [1]. During embryo-genesis, two forms of vascular anomalies cansimultaneously develop from a group of vessels, withsimilar potential in the early stages of evolution. How-ever, this occurrence is rare and, to our awareness, hasnever been reported.

In 1973, Teal et al. proposed using the term accessoryMCA to describe the anomalous vessels originating

from the proximal A1 segment of the ACA [4], thoughthis nomenclature is controversial. The accessoryMCA typically supplies the orbitofrontal, prefrontal,precentral, and/or central vascular territories [5–7].However, in our case, the persistent POA supplied theorbitofrontal area, whereas the accessory MCAextended laterally to supply the temporal lobe as com-pensation for the occluded in situ right MCA.

MCA occlusion may cause abnormal changes in theperforating arteries. The lateral lenticulostriate arteriesnormally arise from the M1 segment of the MCA,whereas the medial striate branches arise from theA1 segment of the ACA. In patients with narrowingor occlusion of the distal ICA or the proximalMCA or ACA, hypertrophy of the lenticulostriatearteries may occur to bypass the occlusive segment.This situation is known as a moyamoya phenomenon.The moyamoya vessels can originate from the acces-sory MCA when the in situ MCA is occluded [8].

Although perforating arteries may originate fromthe accessory MCA [7], they did not provide notablecompensation in our case. Owing to the existence ofthe abnormal ACA, the perforating arteries must arisefrom residual branches of the ICA, such as theAChA. In normal situations, the AChA stems fromthe distal ICA, with branches penetrating the temporallobe near the uncus and with others supplying subcor-tical structures not fed by ACA or MCA perforators[9–11]. Examples of such structures are the internalsegment of the globus pallidus, the optic tract, thechoroid plexus, and the lateral geniculate nucleus.Branches of the AChA are not commonly reportedto compensate for the blood supply of the perforatingarteries in the anterior perforated substance [9–11].

4. Conclusion

To our knowledge, the coexistence of a persistentPOA and accessory MCA with occlusion of an in situipsilateral MCA has never been reported in the litera-ture. In this rare anatomic variant, both the corticalsupply and the compensating perforating arteries werere-disposed. This is an important alteration of the typ-ical circle of Willis and illustrates a unique compensa-tory shift in how blood is supplied to the humanbrain.

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