Occluded distal left M1 internal carotid artery with cerebral ischemia

Case contributed by Henry Knipe
Diagnosis certain


Sudden onset right-sided weakness one hour ago.

Patient Data

Age: 75
Gender: Female

No acute intra- or extra-axial hemorrhage demonstrated. Periventricular and deep white matter hypoattenuation, most in keeping with chronic small vessel ischemic change. Old left cerebellar hemisphere infarct. Hypodensities within both basal ganglia / internal capsules either represent chronic lacunar infarcts or prominent perivascular spaces. Grey-white differentiation is elsewhere preserved. Increased density of the left M1 segment at its bifurcation. Ventricular size, sulcal pattern and basal cisterns all appear age-appropriate.


Increased TMAX along with mildly reduced CBF in the left MCA territory. CBV is largely preserved.

Truncation of the distal left M1 segment.. Heavy calcification of both intracranial internal carotid arteries. Dominant left vertebral artery with PICA termination of the right vertebral artery. Bilateral foetal origin of both posterior cerebral arteries.

Case Discussion

Left distal M1 occlusion with CT perfusion findings indicative of a large ischemic penumbra. No established changes of infarct seen on non-contrast CT.

In early stroke, the brain parenchyma is normal but the vessels should be closely inspected for a hyperdense thrombus.

This patient went on clot retrieval and perfusion re-established to the left MCA territory. 

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