Snapshot A 65-year-old man with a history of chronic alcohol use presents to his primary care clinic. Two years ago, he was hospitalized for acute confusion, vision loss, and unsteady gait, which resolved with thiamine repletion. Since discharge, he has continued to drink alcohol heavily and has developed progressive forgetfulness. He cannot recall recent events. When asked questions, he responds confidently with incorrect answers. Introduction Occurs due to thiamine deficiency Refers to two entities Wernicke encephalopathy acute potentially reversible involves mammillary bodies Korsakoff syndrome chronic irreversible involves mammillary bodies, thalamic regions, and corpus callosum Presentation Clinical diagnosis that does not require imaging studies Wernicke's encephalopathy encephalopathy (disorientation, indifference, inattentiveness) ophthalmoplegia gait ataxia Korsakoff's psychosis memory loss (anterograde and retrograde) confabulation personality change Treatment Thiamine must be administered with glucose to avoid precipitating the onset of Wernicke encephalopathy Prescribe thiamine supplementation to patients at risk