Anterior choroidal artery
The anterior choroidal artery is the preterminal branch of the communicating segment (C7) of the internal carotid artery. It supplies several subcortical structures (limbic system, basal ganglia, diencephalon), midbrain, temporal lobe and visual pathway. Therefore, these structures will be the main ones affected during a stroke of the anterior choroidal artery.
The artery is located within the parahippocampal gyrus, deep within the brain. It gives off approximately eight minor, perforating branches.
This article will discuss the anatomy and function of the anterior choroidal artery.
|Origin||Communicating segment (C7) of internal carotid artery|
Limbic system: amygdala, hippocampus, basal ganglia (globus pallidus, substantia nigra, caudate nucleus), fimbria of fornix
Diencephalon: hypothalamus, lateral geniculate body of thalamus
Midbrain: red nucleus, crus cerebri of midbrain
Visual pathway: optic tract, optic radiation
Others: tela choroidea, posterior limb of the internal capsule
The anterior choroidal artery (AChA) occupies the semi-anular sulcus of the parahippocampal gyrus. It originates from the posterolateral aspect of the internal carotid artery, between the posterior communicating branch (PCOM) and the terminal ICA bifurcation.
The anterior choroidal artery is divided into two segments: cisternal and intraventricular. The proximal cisternal segment initially follows a posterior course. It travels along the medial aspect of the uncus of parahippocampal gyrus and lateral to the optic tract, over which it eventually crosses. The segment continues to the crus cerebri of the cerebral peduncle. From here, its course deviates from posterior to lateral. The cisternal segment then travels around the cerebral peduncle, recrosses the optic tract and reaches the lateral geniculate body of the thalamus. From here, it courses superiorly through the choroid fissure to reach the temporal horn of the lateral ventricle.
The intraventricular segment continues within the lateral ventricle, accompanying the choroid plexus. At this point, it receives the lateral posterior choroidal branch of posterior cerebral artery. The segment then continues superiorly around the thalamus, until the interventricular foramen (of Monro). The anterior choroidal artery finishes at this point by anastomosing with the medial posterior choroidal branch of posterior cerebral artery.
Branches and supply
The anterior choroidal artery gives several off minor, perforating branches:
- The cisternal segment provides eight such branches. They supply the amygdala, hippocampus, globus pallidus, substantia nigra, caudate nucleus, hypothalamus, red nucleus, tela choroidea, posterior limb of the internal capsule, optic tract, crus cerebri of the midbrain and fimbria of the fornix.
- The intraventricular segment supplies the optic tract and the lateral geniculate body of the thalamus.
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The anterior choroidal artery is very thin in caliber, averaging approximately 0.94 mm in diameter. In addition, its perforating branches have a long course and an extensive supply of various brain structures. Therefore, a stroke (ischemic/hemorrhagic) of the anterior choroidal artery can happen very easily and have life-threatening implications. The risk is even higher in the cisternal segment because it is located proximal to the first anastomosis of the anterior choroidal artery.
An anterior choroidal artery stroke can manifest with a variety of signs and symptoms. They can range from lacunar infarct symptoms (hemiparesis, hemiplegia, dysarthria, weakness) to visual field deficits, somnolence, aphasia or neglect. The evolution of such a stroke is also varied. It can severely and negatively progress in some patients, while in others the manifestations can temporarily but completely disappear. The main causes of anterior choroidal strokes are thromboembolisms from the internal carotid artery or small vessel infarcts due to autoimmune conditions (lupus, vasculitis).