Mechanism of acute ischemic stroke in patients with severe middle cerebral artery atherosclerotic disease.

BACKGROUND: Intracranial atherosclerotic disease (ICAD) is one of the most common causes of ischemic stroke worldwide. Although the pathogenesis of cerebral infarct in ICAD has been reported from autopsy series, the mechanism of stroke is not well known. This study used baseline perfusion imaging and diffusion-weighted imaging (DWI) or computerized tomography (CT) imaging to help identify the mechanism of stroke in ICAD involving the middle cerebral artery (MCA).

METHODS: We retrospectively reviewed baseline CT or magnetic resonance (MR) perfusion studies and diffusion-weighted MR imaging or CT scans in patients with severe symptomatic MCA stenosis. Perfusion scans were classified according to stage of perfusion deficit, and the acute stroke patterns were categorized as borderzone, cortical, or perforating artery infarcts according to DWI or noncontrast CT.

RESULTS: Fifteen patients were included in this analysis. All 15 patients had some type of borderzone infarct. Six had borderzone infarct only, 4 had borderzone and cortical infarcts, and 5 had borderzone, cortical, and perforating artery infarcts. Thirteen of the 15 patients had baseline perfusion deficits.

CONCLUSIONS: In patients with severe MCA ICAD, the mechanism of stroke is multifactorial, but hemodynamic insufficiency plays a significant role. This finding is important in selecting a subgroup of patients who may benefit from revascularization.