RT Journal Article SR Electronic T1 Angiographic Analysis of Natural Anastomoses between the Posterior and Anterior Cerebral Arteries in Moyamoya Disease and Syndrome JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A6291 A1 S. Bonasia A1 G. Ciccio A1 S. Smajda A1 A.G. Weil A1 C. Chaalala A1 R. Blanc A1 M. Reinert A1 M. Piotin A1 M. Bojanowski A1 T. Robert YR 2019 UL http://www.ajnr.org/content/early/2019/10/31/ajnr.A6291.abstract AB BACKGROUND AND PURPOSE: Moyamoya disease is a chronic neurovascular steno-occlusive disease of the internal carotid artery and its main branches, associated with the development of compensatory vascular collaterals. Literature is lacking about the precise description of these compensatory vascular systems. Usually, the posterior circulation is less affected, and its vascular flow could compensate the hypoperfusion of the ICA territories. The aim of this study was to describe these natural connections between the posterior cerebral artery and the anterior cerebral artery necessary to compensate the lack of perfusion of the anterior cerebral artery territories in the Moyamoya population.MATERIALS AND METHODS: All patients treated for Moyamoya disease from 2004 to 2018 in 4 neurosurgical centers with available cerebral digital subtraction angiography were included. Forty patients (80 hemispheres) with the diagnosis of Moyamoya disease were evaluated. The presence of anastomoses between the posterior cerebral artery and the anterior cerebral artery was found in 31 hemispheres (38.7%).RESULTS: Among these 31 hemispheres presenting with posterior cerebral artery–anterior cerebral artery anastomoses, the most frequently encountered collaterals were branches from the posterior callosal artery (20%) and the posterior choroidal arteries (20%). Another possible connection found was pio-pial anastomosis between cortical branches of the posterior cerebral artery and the anterior cerebral artery (15%). We also proposed a 4-grade classification based on the competence of these anastomoses to supply retrogradely the territories of the anterior cerebral artery.CONCLUSIONS: We found 3 different types of anastomoses between the anterior and posterior circulations, with different abilities to compensate the anterior circulation. Their development depends on the perfusion needs of the territories of the anterior cerebral artery and can provide the retrograde refilling of the anterior cerebral artery branches.ACAanterior cerebral arteryPCAposterior cerebral artery