Patterns of ischemic posterior circulation strokes: A clinical, anatomical, and radiological review

Abstract

Background: Posterior circulation and anterior circulation strokes share many clinical, pathogenetic and radiological features, although some clinical signs are highly specific to posterior circulation strokes. Arterial stenosis and occlusions occur in significant numbers in both acute posterior circulation and anterior circulation strokes, making them good candidates for endovascular treatment. Among posterior circulation strokes, basilar artery occlusions stand out because of the diagnostic and acute treatment challenges.

Methods: We reviewed the literature on clinical stroke syndromes and neuroimaging findings and systematically describe for each anatomical site of stroke the detailed clinical and radiological information (anatomical representation, diffusion weighted imaging and angiographic sequences). The principles of neuroimaging of posterior circulation strokes and the prognosis for each stroke localization are also discussed.

Review summary: Stroke syndromes in the territories of the vertebral, basilar, cerebellar, and posterior cerebral arteries are presented. Features typical of posterior circulation strokes are highlighted, including patterns of basilar artery occlusions. Clinical severity and prognosis of posterior circulation strokes are highly variable, and given that they are more difficult to detect on CT-based neuroimaging, magnetic resonance imaging is the technique of choice in suspected posterior circulation strokes. Rapid identification of arterial occlusion patterns may provide prognostic information and support acute revascularization decisions.

Conclusions: Posterior circulation stroke syndromes tightly reflect lesion localization and arterial occlusion patterns. Although many clinical and pathogenetic features are similar to anterior circulation strokes, notable differences exist in terms of clinical presentation, stroke mechanism, prognosis, and response to acute recanalization.

Keywords: Basilar artery; Ischemic stroke; Magnetic Resonance Imaging; Prognosis; Vertebrobasilar insufficiency.

Figure 1.

Anatomy and vascularization of the vertebrobasilar system.

Figure 2.

(a) Schematization of pontine syndromes. (b) Pattern of perforating branches in the pons.

Figure 3.

(a) Proximal BA occlusion usually secondary to atheromathosis of the terminal portion of the VA. (b) Mid BA occlusion usually secondary to atheromatosis of the BA. (c) Top of the basilar occlusion usually secondary to cardioembolism.