Presentation
Right sided weakness.
Patient Data
Non contrast CT demonstrates patchy low density seen in the white matter of the left cerebral hemisphere, in a deep watershed distribution.
CT perfusion demonstrates:
- increased mean transit time (MTT); consistent with slow flow
- increased cerebral blood volume (CBV) in the cortex
- decreased cerebral blood flow (CBF) in the white matter
In other words there is a ischemic penumbra (mismatch between MTT and CBF) encompassing the cortex, which has vasodilation (thus elevated CBV).
Angiogram confirms diagnosis of left ICA dissection, seen as a tapering lumen which disappears below the base of skull.
Patient was treated with endovascular stent placement.
Diffusion weighted imaging the next day demonstrates only patchy deep border zone restricted diffusion. Little if any cortical infarction is present.
Case Discussion
This young woman presented with a spontaneous carotid dissection and extensive watershed infarction between underperfused MCA territory on the left and ACA / PCA. The perfusion maps correctly identified an ischemic penumbra encompassing most of the cortex, which was being supplied by collaterals, encouraged by maximal vasodilatation.
Carotid stent placement re-established cortical perfusion and saved this patient from a devastating stroke.
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