Journal of Cerebrovascular Sciences

: 2020  |  Volume : 8  |  Issue : 1  |  Page : 68--70

A rare case of internal carotid artery trifurcation and an aneurysm associated with it

Harshal Agrawal, Joy Varghese, M Balamurugan 
 Department of Neurosurgery, Apollo Hospitals, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. Harshal Agrawal
Department of Neurosurgery, Apollo Hospitals, Chennai, Tamil Nadu


Existing literature is devoid of data on true trifurcations of the internal carotid artery (ICA). The authors present a rare case of trifurcation of the ICA, discovered during the evaluation of a patient with subarachnoid haemorrhage, and discuss the surgical implications of the anomaly.

How to cite this article:
Agrawal H, Varghese J, Balamurugan M. A rare case of internal carotid artery trifurcation and an aneurysm associated with it.J Cerebrovasc Sci 2020;8:68-70

How to cite this URL:
Agrawal H, Varghese J, Balamurugan M. A rare case of internal carotid artery trifurcation and an aneurysm associated with it. J Cerebrovasc Sci [serial online] 2020 [cited 2022 Oct 2 ];8:68-70
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The Middle Cerebral Artery (MCA) is the largest of the cerebral arteries. It is the last major cerebral vessel to develop, from phylogenetic point of view, to cater to the increasing demands of the growing cerebral neocortex. M1 segment of MCA anomalies are less frequent and it may be an accessory MCA, duplicated MCA, fenestrated MCA or an early bifurcation.[1]

In this article, we discuss a case of an early MCA bifurcation nee duplicated MCA, which appeared as an internal carotid artery (ICA) trifurcation on cerebral angiography and review the literature regarding incidence, origins and consequences of the same.

 Case Report

A 46-year-old male presented with a history of sudden and severe headache 1 month back. Computed tomography report (films unavailable) described as right Sylvian Fissure localised haematoma. Cerebral digital subtraction angiography done revealed an M1 segment aneurysm with an ICA “trifurcation.” The patient was successfully managed surgically by clipping of the aneurysm [Figure 1], [Figure 2], [Figure 3], [Figure 4].{Figure 1}{Figure 2}{Figure 3}{Figure 4}


The literature is devoid of any article describing a true ICA trifurcation. It is an anomalous origin of the MCA, which appears as though the ICA terminus has trifurcated into three individual branches. In the literature, Rhoton described this issue in the Supratentorial Arteries section of his book:

“Anomalies of the MCA, consisting of either a duplicate or an accessory MCA. A duplicated MCA is a second artery that arises from the ICA and an accessory MCA is one that arises from the anterior cerebral artery (ACA). Both the duplicate and accessory MCAs send branches to the cortical areas usually supplied by the MCA. The accessory MCAs usually arise from the ACA near the origin of the anterior communicating artery. The accessory MCA is differentiated from a recurrent artery of Heubner (RAH) by the fact that the recurrent artery, although arising from the same part of the ACA as an accessory MCA, enters the anterior perforated substance, but the accessory MCA, although sending branches to the anterior perforated substance, also courses lateral to this area and sends branches to cortical areas normally supplied by the MCA.”[2]

The difference between an accessory MCA and a duplicated MCA was first delineated in 1973.

However, in our case, it appears as if the extra branch of the vessel arises from the ICA terminus and not from ACA and hence cannot be construed as an accessory MCA.

The major dilemma is whether it is truly a duplicated MCA or a very early bifurcation of the MCA. Early bifurcation of the MCA originating as close as 1 mm from the origin of MCA has been reported.[3] The two branches run parallel to each other in the Sylvian Fissure and supply analogous regions of the anterior frontal and anterior temporal lobes. Komiyama et al. described marked similarity in the distribution of early branched MCA to that of an accessory or duplicated MCA.[4]

Surgical importance lies in correct identification of the vessels during surgery. There is literature evidence to support the formation of aneurysm in such a configuration, as illustrated by Kaliaperumal et al., who described an ICA trifurcation aneurysm.[5] They illustrated the possible locations of the aneurysm as (1) Between ACA and MCA – in close proximity to RAH and medially Anterior Choroidal Artery (AChA) or (2) Between two branches of MCA – in close proximity of lateral lenticulostriate vessels; care should be taken preoperatively to elucidate these variations. In our case, however, the aneurysm was located distal to the ”trifurcation” on the possibly superior division of MCA and was clipped successfully without any complication.

The embryological origins of the early bifurcation or accessory or duplicated MCA are still not clear. The MCA actually arises as collateral from the primary intracranial division as the second branch after the AchA. This situation reverses in adulthood as MCA becomes bigger and more dominant over ACA. The variations in MCA should be considered physiological rather than pathological as they are not associated with more vascular anomalies.


A true ICA trifurcation does not exist. It rather represents a variation in the origin of the MCA. It may be difficult to differentiate an early branching MCA from a duplicated MCA, as in our case. Never the less the area of distribution is maintained. The variations may be associated with a vascular anomaly like an aneurysm, as in our case, and care should be taken to delineate the anatomy accurately before surgery.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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3Gibo H, Lenkey C, Rhoton AL. Microsurgical anatomy of the supraclinoid portion of the internal carotid artery. J Neurosurgery 1981;55:560-.
4Komiyama M, Nakajima H, Nishikawa M, Yasui T. Middle cerebral artery variations: Duplicated and accessory arteries. Am J Neuroradiol 1998;19:45-9.
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