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Alexia Without Agraphia – Disconnection Syndrome — SCE Neurology MCQ

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HardCerebrovascular DiseaseAlexia Without Agraphia – Disconnection SyndromeSCE Neurology

A 62-year-old woman presents with progressive difficulty reading (alexia) without agraphia. She can write fluently but cannot read what she has just written. She also has a right homonymous hemianopia. MRI brain shows a left PCA territory infarct involving the left occipital lobe and splenium of the corpus callosum. What is the neuroanatomical explanation?

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Correct answer: D — Disconnection of the intact right visual cortex from the left angular gyrus due to splenial lesion, combined with destruction of the left visual cortex

Alexia without agraphia (pure alexia) results from a left PCA infarct that destroys the left visual cortex (causing right homonymous hemianopia) AND the splenium of the corpus callosum (preventing visual information from the intact right visual cortex from reaching the left angular gyrus, which is necessary for reading). Writing is preserved because the left angular gyrus and motor pathways are intact — the patient simply cannot visually process written text. A: Broca's area damage causes non-fluent aphasia. C: Wernicke's area damage causes receptive aphasia. D: Bilateral occipital infarction causes cortical blindness. E: Frontal damage causes executive dysfunction.

Reference: Clinical Neuroanatomy; Geschwind Disconnection Syndromes