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

Wernicke encephalopathy is an acute disorder which is a triad of ataxia, ophthalmoplegia and confusion. It is caused by thiamine deficiency and is most common in chronic alcoholics, it can also occur from malnutrition from any cause. The major sites of involvement are medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei (especially oculomotor, abducens, and acoustic nerves), and superior cerebellar vermis. Cerebellar and vestibular involvement both contribute to the ataxia. Other classic findings includes an amnestic syndrome or global confusional state, horizontal or combined horizontal veical nystagmus, bilateral lateral rectus palsies, and absent ankle jerks. Ref: Clinical Neurology By Roger P. Simo, 7th Edition, Chapter 3; CURRENT Diagnosis & Treatment Emergency Medicine, 7th Edition, Chapter 37