Anterior cerebral artery syndrome refers to symptoms that follow astroke occurring in the area normally supplied by one of the arteries. It is characterized byweakness and sensory loss in the lower leg and foot opposite to the lesion and behavioral changes.
Arteries of the brain. Anterior cerebral artery labeled at the left (twice)
The anterior cerebral artery is divided into 5 segments. Its smaller branches: the callosal (supracallosal) arteries are considered to be theA4 andA5 segments.[1][2]
A1 originates from the internal carotid artery and extends to theanterior communicating artery (AComm). Theanteromedial central (medial lenticulostriate) arteries arise from this segment as well as the AComm, which irrigates thecaudate nucleus and the anterior limb of theinternal capsule
A2 extends from the AComm to the bifurcation forming thepericallosal andcallosomarginal arteries. Therecurrent artery of Heubner (distal medial striate artery), which irrigates the internal capsule, usually arises at the beginning of this segment near the AComm. Two branches arise from this segment:
Orbitofrontal artery (medial frontal basal): Arises a small distance away from the AComm
Frontopolar artery (polar frontal): Arises after theorbitofrontal, close to the curvature of A2 over thecorpus callosum. It can also originate from thecallosal marginal.
A3, also termed thepericallosal artery, is one of the (or the only) main terminal branches of the ACA, which extends posteriorly in the pericallosal sulcus to form theinternal parietal arteries (superior, inferior) and theprecuneal artery. This artery may form ananastomosis with theposterior cerebral artery.
Callosal marginal artery: A commonly present terminal branch of the ACA, which bifurcates from thepericallosal artery. This artery in turn branches into themedial frontal arteries (anterior, intermediate, posterior), and theparacentral artery, with thecingulate branches arising throughout its length. Depending onanatomical variation, thecallosal marginal artery may be none discrete or not be visible. In the latter case, the branches mentioned will originate from thepericallosal artery. In a study of 76 hemispheres, the artery was present in only 60% of the cases.[3] Angiography studies cite that the vessel can be seen 67%[1] or 50%[4] of the time.
The anterior cerebral artery develops from a primitive anterior division of theinternal carotid artery that initially supplies the optic and olfactory regions. This anterior division, which appears at the twenty-eighth day of development, also forms themiddle cerebral artery and theanterior choroidal artery. The anterior cerebral arteries grow toward each other and form theanterior communicating artery at the 21–24 mm stage of theembryo.[5]
The anterior cerebral artery shows considerable variation. In a study made usingMRA, the most common variation was an underdeveloped A1 segment (5.6%), followed by the presence of an extra A2 segment (3%). In 2% of cases there was only one A2 segment.[6]
The anterior cerebral artery supplies a part of the frontal lobe, specifically its medial surface and the upper border. It also supplies the front four–fifths of thecorpus callosum, and provides blood to deep structures such as the anterior limb of theinternal capsule, part of thecaudate nucleus, and the anterior part of theglobus pallidus.[7]
Strokes that occur in a part of the artery prior to the anterior communicating usually do not produce many symptoms because ofcollateral circulation. If a blockage occurs in the A2 segment or later, the following signs and symptoms may be noted:[8]
Paralysis or weakness of the foot and leg on the opposite side, due to involvement of leg part of themotor cortex
Cerebral arteries seen from beneath. Anterior cerebral artery visible at centre.
Thearterial circle and arteries of the brain (inferior view). The anterior cerebral arteries (top of figure) arise from the trifurcations of theinternal carotid arteries.
