What is the pathophysiology of visual field loss in posterior cerebral artery (PCA) stroke?

Updated: Jul 30, 2018
  • Author: Erek K Helseth, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Unilateral infarction produces homonymous hemianopia. Sparing of the macula is encountered frequently in infarction of the occipital lobes due to PCA occlusion. Macular sparing may be caused by collateral vascular supply to the macular region or by the very large macular representation in the occipital cortex; additionally, bilateral representation of macular vision has been suspected.

Bilateral infarctions of the occipital lobes produce varying degrees of cortical blindness depending on the extent of the lesion. Patients often exhibit Anton syndrome, a state in which they fervently believe they can see when they cannot. Patients may describe objects that they have not seen previously in exquisite detail, completely in error and oblivious to that error.

Another intriguing phenomenon is blindsight. Although cortically blind, patients can respond to movement or sudden lightening or darkening of their environment.

Infarction of the lateral geniculate nucleus may produce hemianopia, quadrantanopia, or sectoranopia. The vascular supply is dual; the anterior choroidal artery supplies the anterior hilum and anterolateral areas, and the posterior choroidal artery supplies the rest. Occlusion of the posterior choroidal artery may produce a distinct syndrome of hemianopia, hemidysesthesia, and memory disturbance due to infarction of the lateral geniculate, fornix, dorsomedial thalamic nucleus, and posterior pulvinar.


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