A chronic alcoholic presents after an episode of confusion with nystagmus and ophthalmoplegia that resolved with thiamine replacement. He now has dense anterograde amnesia and fills gaps in memory with detailed fabricated stories he believes to be true. Which brain region shows the characteristic pathological lesion?

• A Mammillary bodies ✓
• B Hippocampal CA1 sector alone
• C Frontal operculum
• D Caudate nucleus

Explanation

Wernicke encephalopathy followed by Korsakoff psychosis produces lesions in the mammillary bodies and periaqueductal gray matter of the thalamus, giving anterograde amnesia with confabulation. Confabulation is unintentional fabrication, not lying, because the patient cannot distinguish real memories from invented ones. Isolated CA1 damage causes global amnesia after ischemic insults, caudate degeneration characterizes Huntington disease, and frontal opercular lesions produce Broca aphasia rather than amnesia.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.