Following rupture of an anterior communicating artery aneurysm, a 55-year-old man lies awake but makes no spontaneous movement or speech. When questioned he answers briefly and correctly, yet initiates nothing on his own. Which structure is most likely damaged?

• A Orbitofrontal cortex bilaterally
• B Mammillary bodies
• C Dominant temporoparietal association cortex
• D Anterior cingulate cortex and supplementary motor area ✓

Explanation

Abulia, a state of profound apathy with reduced spontaneous initiation but preserved responsiveness to prompting, localises to medial frontal structures supplied by the anterior cerebral artery, chiefly the anterior cingulate cortex and supplementary motor area. Orbitofrontal damage produces disinhibition rather than apathy. Temporoparietal lesions cause aphasic or neglect syndromes, and mammillary body injury causes anterograde amnesia as in Wernicke-Korsakoff syndrome.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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