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Neuroradiology Case of
the Week
Case 135
Fariha Ahsan, Ravinder Sidhu MD, and PL Westesson MD, DDS, PhD
Clinical
Presentation: Patient is a
50-year old hypertensive female with family history of early strokes.
Radiological
Findings: Diffusion-weighted images were unremarkable (Fig. 1). 3D Time of Flight image revealed presence of two branches of left middle cerebral artery (Fig. 2A). The reconstructed image showed origin of a vessel from distal most part of internal carotid artery. This branch seems to course along the middle cerebral artery in sylvian part (Fig. 2B).
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| Figure 1: Diffusion-weighted image doesn't show acute infarct. |
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| Figure 2A: Appearance of additional branch along left middle cerebral artery. |
Figure 2B:
The additional branch in left middle cerebral artery appears to originate from distal most portion of left internal carotid artery. |
Diagnosis:
Duplication of left middle cerebral artery
Discussion: Middle Cerebral Artery (MCA) is the larger of the two terminal internal carotid artery branches and is divided into four segments; M1 is the horizontal segment, M2 is the insular segment, M3 is the opercular segment and M4 are the cortical branches also known as the M4 segments.
The frequency of MCA duplication is reported to be 0.2%-0.9%. The duplicated vessel arises from the internal carotid artery prior to its terminal bifurcation and parallels the course of the main M1 segment, running below it. It supplies the cortical territory of the temporopolar and the anterior temporal and/or middle temporal arteries. Other MCA anomalies include hypoplasia and aplasia, accessory MCA, partial duplication or fenestrated MCA, anomalous origin of MCA branches and a single non-bifurcating MCA trunk. MCA variations are found incidentally on cranial magnetic resonance angiography (MRA).
Other congenital variations of MCA include early bifurcation, accessory middle cerebral artery, and fenestrated middle cerebral artery. Normally, middle cerebral artery courses for an approximate length of 1.5 cm from its origin before bifurcation. The bifurcation before this length of middle cerebral artery leads to early bifurcation. The accessory middle cerebral artery arises from anterior cerebral artery. Due to an increased hemodynamic stress, congenital anomalies of the intracranial arteries predispose to the formation of saccular aneurysms. The double vascularization of the hemisphere in cases of anatomical duplication can give rise to strokes with a better progression and prognosis, despite the occlusion of one of the MCA. The presence of anatomical variations of the MCA can also lead to mistaken interpretations of the transcranial Doppler scan and may affect decision making as regards the therapy to be employed in patients with acute stroke.
References:
- Uchino A, Sawada A, Takase Y, Kudo S. MR angiography of anomalous branches of the internal carotid artery. AJR Am J Roentgenol. 2003; 181(5):1409-1414. [Medline]
- Elmac I, Baltacioglu F, Ekinci G, Erzen C, Pamir N. Middle cerebral artery duplication associated with multiple intracranial aneurysms. Case report. J Neurosurg Sci. 2001 Dec; 45(4):232-4; discussion 234. [Medline]
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