Bilateral anterior cerebral artery territory infarction in the differential diagnosis of basilar artery occlusion.

Two patients with bilateral anterior cerebral artery (ACA) territory infarction are presented whose initial diagnosis was basilar artery occlusion. Both had tetraparesis; in one it was asymmetrical. Both had their eyes open and did not respond to command except that after a delay they followed with their eyes a smoothly moving object; this was the only sign of awareness. One patient had a clear vertical gaze palsy in the upward and downward direction unaccompanied by pupillary abnormalities. Computed tomography revealed fresh bilateral ACA infarction in both patients; occlusion in the hind brain circulation was excluded by angiography in one. Both patients suffered from atrial fibrillation, so cardiac embolism was the most likely cause of the stroke. We conclude that bilateral ACA territory infarction should be considered in the differential diagnosis of basilar artery occlusion, even if accompanied by vertical gaze palsy.