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A New, More Accurate Classification of Middle Cerebral Artery Aneurysms: Computed Tomography Angiographic Study of 1009 Consecutive Cases With 1309 Middle Cerebral Artery Aneurysms

Elsharkawy, Ahmed MD*,‡; Lehečka, Martin MD, PHD*; Niemelä, Mika MD, PhD*; Billon-Grand, Romain MD*,§; Lehto, Hanna MD*; Kivisaari, Riku MD, PhD*; Hernesniemi, Juha MD, PhD*

doi: 10.1227/01.neu.0000429842.61213.d5
Research-Human-Clinical Studies

BACKGROUND: Classification of middle cerebral artery (MCA) aneurysms is sometimes difficult because the identification of the main MCA bifurcation, the key for accurate classification of MCA aneurysms, is inconsistent and somewhat subjective.

OBJECTIVE: To use the meeting point of the M1 and M2 trunks as an objective, generally accepted, and angiographically evident hallmark for identification of MCA bifurcation and more accurate classification of MCA aneurysms.

METHODS: We reviewed the computed tomographic angiography data of 1009 consecutive patients with 1309 MCA aneurysms. The M2 trunks were followed proximally until their meeting with the M1 trunk at the main MCA bifurcation. The aneurysms were classified according to their relative location: proximal, at, or distal to the MCA bifurcation. The M1 aneurysms were further subgrouped into M1 early cortical branch aneurysms and M1 lenticulostriate artery aneurysms, extending the classic 3-group classification of MCA aneurysms into a 4-group classification.

RESULTS: The main MCA bifurcation was the most common location for MCA aneurysms, harboring 829 aneurysms (63%). The 406 M1 aneurysms comprised 242 M1 early cortical branch aneurysms (60%) and 164 M1 lenticulostriate artery aneurysms (40%). We found 106 MCA aneurysms (8%) at the origin of large early frontal branches simulating M2 trunks liable to be misclassified as MCA bifurcation aneurysms. Even though 51% of the 407 ruptured MCA aneurysms were associated with an intracerebral hematoma, this did not affect the classification.

CONCLUSION: Studying MCA angioarchitecture and applying the 4-group classification of MCA aneurysms is practical and facilitates the accurate classification of MCA aneurysms, helping to improve surgical outcome.

ABBREVIATIONS: CTA, computed tomographic angiography

MCA, middle cerebral artery

MCAA, middle cerebral artery aneurysm

MdistA, middle cerebral artery distal aneurysm

MbifA, middle cerebral artery bifurcation aneurysm

M1A, proximal middle cerebral artery aneurysm

M1-ECBA, M1 early cortical branch aneurysm

M1-LSAA, M1 lenticulostriate artery aneurysm

*Department of Neurosurgery, Helsinki University Central Hospital, Helsinki, Finland;

Department of Neurosurgery, Tanta University, Tanta, Egypt;

§Department of Neurosurgery, Minjoz University Hospital, Besançon, France

Correspondence: Ahmed Elsharkawy, MD, Department of Neurosurgery, Helsinki University Central Hospital, Topeliuksenkatu 5, 00260 Helsinki, Finland. E-mail: or

Received December 11, 2012

Accepted March 13, 2013

Copyright © by the Congress of Neurological Surgeons