Middle Cerebral Artery Duplication : Classification and Clinical Implications

Abstract

Objective : Although there are several explanations for a duplicated middle cerebral artery (DMCA), its embryological origin is still an open question. We reviewed these anomalous vessels to postulate a theory of their different origins, sizes, and courses. Methods : A retrospective review of 1,250 cerebral angiographies, 1,452 computed tomography (CT)-angiographies, and 2,527 magnetic resonance (MR)-angiographies was performed to identify patients with DMCA. Results : Twenty-five patients had 25 DMCAs. Conventional angiography detected nine patients with DMCA (9/1250, 0.72%), MR-angiography detected seven patients with DMCA (7/2527, 0.28%), and CT-angiography detected nine patients with DMCA (9/1452, 0.62%). The DMCAs originated near the internal carotid artery terminal in eight patients (type A), and between the origin of the anterior choroidal artery and the terminal internal carotid artery in 17 patients (type B). The diameters of the eight type A DMCAs were the same or slightly smaller than those of the other branch of the DMCA. All type A DMCAs showed a course parallel to that of the other branch of the DMCA. The diameters of the 17 type B DMCAs were the same, slightly smaller, or very much smaller than that of the other branch of the DMCA. Nine type B DMCAs showed parallel courses, and the other eight curved toward the temporal lobe. Conclusion : The two branches of the type A DMCAs can be regarded as early bifurcations of the MCA. The branches of the type B DMCAs had parallel courses or a course that curved toward the temporal lobe. The type B DMCA can be regarded as direct bifurcations of the MCA trunk or the early ramification of the temporal branch of the MCA.

Correlation between multiple cerebral aneurysms and a rare type of segmental duplication of the middle cerebral artery

“…The frequency of type B is twice as common as type A. Since in our case, the DMCA and ACA branches have almost identical diameters, it could be said that this is actually ICA trifurcation [1]. However, one of the peculiarities of our case is the presence of anastomosis between the duplicated MCA branches at the point where the MCA branching would normally occur (Fig.3).…”

“…Anatomical variations of the middle cerebral artery (MCA) are significantly less common than those of other intracranial arteries [1,2]. The most frequent anatomical variations of the MCA are duplication of the middle cerebral artery (DMCA), accessory middle cerebral artery (accessory MCA) and fenestration of the middle cerebral artery (MCA fenestration) (Fig.…”

“…1). The incidence of DMCA ranges from 0.7 to 2.9% in autopsy studies [3] and 0.24 to 1.5% in angiographic studies [1,4]. In 1962, Crompton was among the first to report the existence of MCA anomaly, such as duplication of the MCA, accessory MCA and fenestration of the MCA [5].…”

“…The DMCA was classified into two types, Type A and Type B. Type A refers to the duplication of the middle cerebral artery which separates from the ICA bifurcation, and Type B refers to the blood vessel that arises from the ICA between the anterior choroidal artery (AChA) and bifurcation of the internal carotid artery [1,4,5,8]. Its embryonic origin is still an open question.…”

Anatomical variations of anterior circulation in the brains of patients with and without intracranial aneurysm

“…The accessory MCA arises from the A1 segment of the ACA (15,16). The duplicated MCA usually supplies the temporal lobe (15,17).…”