A 52-year-old male with a long history of alcohol use disorder is brought to the emergency department by his partner for acute confusion over the past 48 hours. He has poor nutritional intake and has been drinking heavily for the past several weeks. On examination, he displays horizontal nystagmus, bilateral sixth cranial nerve palsies, and a broad-based ataxic gait. His speech is confused and he cannot recall three objects after five minutes. Laboratory results show mildly elevated liver enzymes (AST 98, ALT 62), but ammonia level is within normal limits at 28 mcg/dL. His partner reports no prior episodes of confusion, and there is no asterixis on examination. Which of the following is the most likely diagnosis?