Paradoxical cerebral embolism causing internal carotid artery occlusion.

Paradoxical cerebral embolism (PCE) is defined to be a pathological condition in which emboli originating from the venous system reach the cerebral arterial circulation via the right-to-left (R-L) shunt. In patients with PCE, emboli originating from the venous system most commonly pass through the patent foramen ovale during Valsalva-provoking activities which increase the right atrial pressure above the left atrial pressure. The size of cerebral infarction caused by PCE is generally small, since the size of emboli which can pass through the R-L shunt is small. Here, we report a case of PCE which occluded the internal carotid artery (ICA).