What are the most common vascular territories affected by stroke?

From the Guidelines

The most common vascular territory affected by stroke is the middle cerebral artery (MCA) territory, which accounts for approximately 50-75% of all ischemic strokes. This is because the MCA supplies a large portion of the lateral cerebral hemisphere, including the lateral frontal, temporal, and parietal lobes, making it more susceptible to occlusion from emboli or thrombosis 1. The MCA territory is often affected due to its large size and the fact that it carries a significant amount of blood flow, making it more vulnerable to embolic events from cardiac or large vessel sources.

Some of the key factors that contribute to the high incidence of MCA territory strokes include:

• The MCA's large size and blood flow, which make it more susceptible to occlusion
• The presence of early infarction signs, such as loss of gray-white matter distinction, hypodensity or hypoattenuation, and sulcal effacement or compression of CSF spaces, which can be detected within 6 hours of onset of symptoms in up to 82% of patients with ischemia in the MCA territory 1
• The correlation between widespread signs of early infarction and a higher risk of hemorrhagic transformation following treatment with thrombolytic agents 1

Other vascular territories, such as the anterior cerebral artery (ACA), posterior cerebral artery (PCA), vertebrobasilar system, and lacunar territories, are also affected by stroke, but to a lesser extent. The ACA territory, which supplies the medial portions of the frontal and parietal lobes, accounts for about 10-15% of strokes, while the PCA territory, which supplies the occipital lobe and parts of the temporal lobe, represents approximately 10-15% of strokes. The vertebrobasilar system and lacunar territories account for roughly 20% and 20-25% of ischemic events, respectively.

From the Research

Vascular Territories Affected by Stroke

The most common vascular territories affected by stroke are:

• Middle cerebral artery (MCA) territory, which includes the superficial and deep areas of the lateral surface of the cerebral hemisphere 2, 3, 4
• Posterior cerebral artery (PCA) territory, which is often associated with small artery disease 3
• Watershed areas, which are prone to infarcts due to large artery disease 3
• Entire MCA territory, which is commonly affected by emboligenic heart disease and cardioembolic stroke 3, 4

Specific Areas Affected

The territories of the perforating (lenticulostriate) branches of the middle cerebral artery supply:

• The caudate nucleus
• The putamen
• The globus pallidus
• The basal forebrain
• The internal capsule
• The corona radiata
• The cerebral cortex 5

Etiology and Outcome Patterns

Large infarcts in the MCA territory are often associated with:

• Cardiogenic embolism
• Internal carotid artery (ICA) occlusion
• ICA dissection
• Severe neurologic deficit, including hemiplegia, hemisensory loss, and global aphasia 4
• High mortality and severe disability rates, with brain edema being a common cause of death 4