A 71-year-old man suffers a left posterior cerebral artery infarct. He can write fluently but cannot read even his own writing; naming objects by touch is preserved and there is a right homonymous hemianopia. Interruption of fibres running in which structure accounts for the reading deficit?

• A Splenium of the corpus callosum ✓
• B Genu of the corpus callosum
• C Anterior commissure
• D Arcuate fasciculus

Explanation

This is alexia without agraphia. The left PCA infarct destroys the left visual cortex, so visual information from the right field cannot reach language areas. Fibres from the intact right visual cortex cross to the left angular gyrus through the splenium of the corpus callosum, and when the splenium is also involved this transfer fails, leaving reading abolished while writing and other language functions remain intact. The arcuate fasciculus connects frontal and temporal language areas and its lesion causes conduction aphasia with impaired repetition.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.