A 40-year-old man with a 20-year history of alcohol abuse is brought to the hospital by his friends because he was difficult to rouse. He ate a large meal several hours ago. He is emaciated and lethargic. Examination shows severely restricted horizontal eye movements and ataxia of both upper extremities. The most likely cause of these findings is a deficiency of which of the following nutrients?
Folic acid
Vitamin A
Vitamin B1 (thiamine)
Vitamin B6 (pyridoxine)
Vitamin B12 (cobalamin)
Correct answer
Vitamin B1 (thiamine)
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correct answer: C
This patient is exhibiting signs of Wernicke’s encephalopathy, a condition of thiamine deficiency. The classic triad of Wernicke’s is encephalopathy, ophthalmoplegia in the form of lateral gaze nystagmus, and ataxia. Chronic alcoholics and indivduals undergoing TPN without B1 supplements are predisposed to B1 deficiency. Wernicke’s may be precipitated by carbohydrate heavy meals because thiamine is a cofactor for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase, key enzymes in glucose metabolism. Untreated Wernicke’s encephalopathy may progress to Korsakoff syndrome, an irreversible condition characterized by psychosis, anterograde and retrograde amnesia, and confabulation.