A 45-year male with a history of alcohol dependence presents with confusion, nystagmus and ataxia. Examination reveals 6th cranial nerve weakness. What is he is most likely to be suffering from?

Patient in the question is showing features of Wenicke's encephalopathy. It is manifested by confusion, ataxia, and nystagmus. It can occur as a result of thiamine deficiency. The lesions caused by thiamine deficiency occur in the hippocampus, the mammillary bodies, and the anterior and dorsal nucleus of the thalamus, and disrupt the Papez circuit. Ref: Current Diagnosis and Treatment Emergency Medicine, 7th edition Chapter 37; Current Diagnosis and Treatment: Psychiatry, 2nd edition Chapter 14.