Anterior circulation infarction

Last revised by Frank Gaillard on 22 Dec 2022

Anterior circulation infarction describes any infarct in an area of the brain that is within the vascular territory of the anterior circulation, which includes most of the supratentorial structures excluding the occipital lobes. These structures derive their arterial supply from the internal carotid arteries which form part of the anastomotic circle of Willis.

Refer to each specific article for detailed discussion of the various anterior circulation infarcts:

Anterior circulation infarctions account for 70-80% of all ischemic strokes 1.

The acute stroke syndrome associated with an anterior circulation infarct is highly dependent on the structures affected. Dysphasia and the presence of both sensory and motor deficits on the same side of the body are generally suggestive of anterior circulation involvement 2. In all cases, clinicians must maintain a high index of suspicion for posterior circulation stroke by assessing for brainstem signs (e.g. dizziness/vertigo, dysarthria, dysphagia, diplopia, ataxia) 2.

Differentiating anterior from posterior circulation disease based solely on clinical neurologic deficits is a perilous task; neuroimaging is vital to accurately localize cerebral infarction 3.

The Bamford classification separates anterior circulation stroke into two clinical types, based on the presence or absence of three components 4:

  1. unilateral weakness and/or sensory deficit of at least two areas (out of face, arm and leg)

  2. homonymous visual field defect

  3. higher cerebral dysfunction (e.g. dysphasia, visuospatial disorder)

Under the Bamford classification, total anterior circulation stroke (TACS) requires the presence of all three of the above components, whereas partial anterior circulation stroke (PACS) requires only two of the three. Isolated higher cerebral dysfunction is also classified as PACS 4.

Once imaging evidence of infarct is obtained, the type of stroke may be coded as total anterior circulation infarct (TACI) or partial anterior circulation infarct (PACI) 4.

Broadly, the most common cause of anterior circulation infarct is embolism, which includes thromboembolism of cardiac origin, alongside atherosclerotic embolism from proximal intracranial vessels, the carotids and aorta 5. Less common causes include vasculopathies, hematologic disorders, hypercoagulability and arterial dissection. Internal carotid artery dissection is a cause of anterior circulation infarct that may occur at any age but is disproportionately common in younger patients 5.

Refer to each specific article for detailed discussion of the radiographic features of infarction in the various arterial territories within the anterior circulation, in addition to the general article on ischemic stroke.

For treatment of patients with anterior circulation infarction secondary to large artery occlusion, there is a growing body of evidence from randomized trials to support endovascular clot retrieval in addition to best medical therapy as being superior to best medical therapy alone 2.

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