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PCA Infarct – Macular Sparing — SCE Neurology MCQ

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ModerateCerebrovascular DiseasePCA Infarct – Macular SparingSCE Neurology

A 62-year-old man presents with a 3-day history of acute onset right hemianopia with macular sparing. MRI brain shows a left posterior cerebral artery territory infarct affecting the occipital lobe but sparing the occipital pole. What anatomical feature explains the macular sparing?

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Correct answer: D — The occipital pole has dual blood supply from both the posterior and middle cerebral arteries

Macular sparing in PCA territory infarcts is explained by the dual blood supply of the occipital pole (where macular vision is represented). The occipital pole receives collateral supply from branches of the middle cerebral artery in addition to the PCA. Therefore, PCA occlusion may spare the macular representation at the occipital pole, preserving central vision. A: The macula is represented in the occipital cortex, not the frontal lobe. C: The LGN processes visual information but the cortical representation explains macular sparing. D: The calcarine sulcus does process macular vision (at the occipital pole). E: While there is bilateral cortical representation of the macula, the dual blood supply is the primary explanation for macular sparing in PCA strokes.

Reference: Clinical Neuroanatomy; RCP National Clinical Guideline for Stroke (2023)