PMC9479551_01
(a) Magnetic resonance angiography revealing the aneurysm located near the top of the right internal carotid artery (ICA) between two middle cerebral arteries (MCAs). (b) Cerebral angiography demonstrating two MCAs originating from the top of the right ICA and revealing a 6-mm-sized aneurysm located between these two MCAs. These MCAs appeared to be the "true" MCA (arrow) and duplicated MCA (arrowhead). The ipsilateral A1 segment of the anterior cerebral artery was not visualized due to hypoplasia.
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Magnetic resonance angiography revealed an aneurysm located near the top of the right internal carotid artery (ICA) between two middle cerebral arteries (MCAs) [Figure 1a]. Cerebral angiography demonstrated two MCAs originating from the top of the right ICA and revealed a 6-mm-sized aneurysm located between these two MCAs [Figure 1b].
The aneurysm was located at the bifurcation of two middle cerebral arteries (MCAs) (arrows) (a). After clipping of the aneurysm (b), the hypoplastic A1 (arrow) segment of the anterior cerebral artery was observed at approximately 2 mm proximal to the bifurcation of the MCAs (c and d).
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The aneurysm was observed at the bifurcation of the two MCAs [Figure 2a]. After complete clipping of the aneurysm [Figure 2b], the hypoplastic A1 was observed at approximately 2 mm proximal to the bifurcation of the MCAs [Figures 2c and d].
When the position of the "second" middle cerebral artery (MCA) (arrow) branches at the same as or proximal to the position where the A1 segment of the anterior cerebral artery branches, the second MCA can be called duplicated MCA (a and b). When it (arrow) branches distal to where the A1 branches, it means that the M2 trunk originates from the prebifurcation segment of M1 (c and d).
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In cases wherein the position of the "second" MCA branches at the same as or proximal to the position where the ACA branches, the "second" MCA can be referred to as DMCA [Figures 3a and b]. When it branches distal to where the ACA branches are, it means that MCA trunk originates from the prebifurcation segment of M1 [Figures 3c and d].