Understanding Neurology

Disorders of special senses 117103aCASE 4 (continued)He has physical markers of vascular risk(xanthelasma and hypertension). The visualdeficit is homonymous and hemianopic, whichplaces the lesion in the optic tract, radiation, orcortex. In keeping with this, examination of opticnerve function (acuity, pupils, and fundi) isnormal. The congruous nature and fact that themacula is spared suggest an anterior visual cortexlesion. His cerebellar signs are likely to besequelae of the first event 4 weeks previously.Computed tomography (CT) scanningrevealed two discrete infarctions (103a, b). Thefirst, older and more circumscribed, was locatedin the left cerebellar hemisphere. The second,poorly defined and associated with someswelling, affected the right occipital lobe in theterritory of the posterior cerebral artery.Angiography revealed atherosclerosis of thebasilar artery, a proximal embolic source for bothof these arterial lesions. Echocardiography wasnormal. The patient was treated withantithrombotics to protect against further events.Proceeding to vascular imaging is importantbecause two events occurred in the same vascularsystem. It was important to investigate for acommon proximal embolic source (in this caseatherosclerosis in the basilar artery).103b103 Computed tomography scan of vascular disease. a: olderinfarction in the territory of the left superior cerebellar artery;b: newer infarction in the territory of the right posteriorcerebral artery.