A chronic alcoholic is brought to the emergency department with confusion, ataxia, and painful eye movements. The 6th cranial nerve is also involved. What is the likely diagnosis?

Correct Answer: A. Wernicke's encephalopathy

Wernicke's encephalopathy is an acute neuropsychiatric emergency caused by thiamine (vitamin B1) deficiency, classically seen in chronic alcoholics who have poor nutritional intake and impaired thiamine absorption. The classic triad comprises confusion, ataxia, and ophthalmoplegia (painful eye movements due to 6th cranial nerve involvement causing horizontal nystagmus and diplopia). The 6th nerve palsy is a hallmark finding that distinguishes this from other alcohol-related conditions. Thiamine is essential for carbohydrate metabolism and myelin synthesis; deficiency leads to selective damage to the mammillary bodies, medial thalamus, and periaqueductal gray matter. In India, chronic alcoholics with poor socioeconomic status and inadequate diet are at highest risk. The condition is a medical emergency requiring immediate IV thiamine replacement (100 mg daily) to prevent irreversible progression to Korsakoff psychosis. Early recognition and treatment can reverse symptoms within days to weeks. The presence of 6th nerve involvement (ophthalmoplegia) is the discriminating clinical sign that points definitively to Wernicke's encephalopathy rather than other alcohol-related syndromes.

Why the other options are wrong

B. De Clerambault syndrome — De Clerambault syndrome is a delusional disorder characterized by the false belief that another person is in love with the patient. It is a psychiatric condition unrelated to thiamine deficiency and does not present with neurological signs like ataxia, ophthalmoplegia, or confusion. This is an NBE distractor that tests whether students can distinguish between psychiatric syndromes and organic neurological emergencies. C. Delirium tremens — Delirium tremens is an acute withdrawal syndrome occurring 12–48 hours after cessation of alcohol, presenting with autonomic hyperactivity (tachycardia, hypertension, fever), tremor, hallucinations, and agitation. While it occurs in chronic alcoholics, it does NOT cause the classic triad of confusion + ataxia + ophthalmoplegia with 6th nerve involvement. Delirium tremens is a withdrawal phenomenon, not a nutritional deficiency state. D. Korsakoff psychosis — Korsakoff psychosis is the chronic sequela of untreated Wernicke's encephalopathy, presenting with anterograde and retrograde amnesia, confabulation, and personality changes—but WITHOUT acute ophthalmoplegia or ataxia. The presence of acute painful eye movements and 6th nerve palsy indicates the acute phase (Wernicke's), not the chronic amnestic phase. Korsakoff develops only after Wernicke's is missed or inadequately treated.

High-Yield Facts

Mnemonics

CAO for Wernicke's Confusion + Ataxia + Ophthalmoplegia (6th nerve) = Wernicke's encephalopathy. Remember: acute onset in chronic alcoholic = thiamine emergency. Wernicke vs Korsakoff Wernicke = ACUTE (confusion, ataxia, eye palsies, reversible with thiamine). Korsakoff = CHRONIC (amnesia, confabulation, irreversible). Wernicke untreated → Korsakoff.

NBE Trap

NBE pairs ophthalmoplegia with delirium tremens to lure students who know alcohol withdrawal causes neuropsychiatric symptoms. However, delirium tremens presents with autonomic hyperactivity and tremor, NOT cranial nerve palsies—the 6th nerve involvement is pathognomonic for Wernicke's thiamine deficiency.

Clinical Pearl

In Indian emergency departments, chronic alcoholics presenting with acute confusion and ataxia are often misdiagnosed as delirium tremens and given benzodiazepines alone. Always check for ophthalmoplegia (ask about diplopia, test horizontal eye movements) and give IV thiamine immediately—this single intervention can prevent permanent brain damage and progression to irreversible Korsakoff psychosis.

_Reference: Harrison Ch. 386 (Nutritional and Metabolic Diseases of the Nervous System); KD Tripathi Ch. 32 (Vitamins); Park's Textbook of Preventive and Social Medicine (Nutritional Deficiency Disorders)_