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Bilateral Altitudinal Hemianopia – PCA Infarcts — SCE Neurology MCQ

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HardNeuro-ophthalmologyBilateral Altitudinal Hemianopia – PCA InfarctsSCE Neurology

A 70-year-old man presents with sudden loss of vision in the superior visual field of both eyes. Examination reveals a bilateral inferior altitudinal visual field defect. Pupillary responses are normal. MRI brain shows bilateral superior occipital infarcts. What vascular territory is affected?

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Correct answer: E — Posterior cerebral arteries (bilateral calcarine cortex — superior banks)

Bilateral inferior altitudinal field defects (loss of vision in the upper visual field bilaterally) localise to the bilateral superior banks of the calcarine cortex, which represent the inferior visual field. These are supplied by the posterior cerebral arteries (PCAs). Bilateral PCA territory infarcts can occur with 'top of the basilar' syndrome. Normal pupillary responses confirm post-chiasmatic pathology (pupils react normally as the pupillary light reflex pathway is via the pretectal area, not the calcarine cortex). A: ACA territory does not include visual cortex. C: MCA territory does not include calcarine cortex. D: Ophthalmic artery supplies the retina. E: PICA supplies lateral medulla and inferior cerebellum.

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