<prompt> Occlusion of internal carotid artery causes all EXCEPTAtaxiaUnilateral blindnessHemiparesisHemiplegia  <response>: A Ataxia INTERNAL CAROTID ARTERY The clinical picture of internal carotid occlusion varies depending on whether the cause of ischemia is propagated thrombus embolism, or low flow. When the origins of both the ACA and MCA are occluded at the top of the carotid artery, abulia or stupor occurs with hemiplegia, hemianesthesia, and aphasia or anosognosia. When the PCA arises from the internal carotid artery a configuration called a fetal posterior cerebral artery, it may also become occluded and give rise to symptoms referable to its peripheral territory. In addition to supplying the ipsilateral brain, the internal carotid artery perfuses the optic nerve and retina via the ophthalmic artery. In about 25 of symptomatic internal carotid disease, recurrent transient monocular blindness amaurosis fugax warns of the lesion. 