Hepatic Encephalopathy — Triphasic Waves

A 58-year-old man with decompensated alcoholic cirrhosis presents with 3 days of worsening confusion, day-night reversal, and asterixis. Serum ammonia is 148 μmol/L. An EEG (marked **B**) shows bilaterally synchronous, generalized triphasic waves at 1.5–2 Hz with maximal amplitude in the frontal regions and anterior-to-posterior lag. Which of the following is the most likely cause of this EEG pattern?

A 58-year-old man with Child-Pugh Class C cirrhosis presents with progressive confusion, asterixis, and disorientation to time and place. Serum ammonia is 165 micromol/L and he meets West Haven Grade 3 hepatic encephalopathy criteria. An EEG is performed to characterize the encephalopathy and exclude non-convulsive status epilepticus. The structure marked **B** in the diagram—generalized high-amplitude triphasic waves at 1.5–2.5 Hz with anterior-posterior phase lag—is documented. Which of the following clinical scenarios would also be expected to produce this same EEG finding?