Soru

A 71-year-old retired architect is brought to the neurologist by his daughter due to a 9-month history of progressive cognitive decline. Initially, he began having difficulty organizing his finances and interpreting architectural blueprints. Six months ago, he started experiencing vivid episodes during sleep where he thrashes around and shouts, sometimes injuring his wife. Over the last 3 months, he has reported seeing silent, unfamiliar children playing in his living room, though he is generally not distressed by them. He has a history of major depressive disorder treated with sertraline. Two weeks ago, his primary care physician suspected an underlying bipolar diathesis but ultimately only increased his sertraline dose. A few days later, he was prescribed linezolid at an urgent care clinic for a suspected skin infection. A thyroid panel obtained last week showed a TSH of 0.1 μU/mL (normal: 0.4-4.0 μU/mL) and a free T4 of 0.6 ng/dL (normal: 0.9-1.7 ng/dL). On physical examination today, his temperature is 37.1°C (98.8°F), blood pressure is 128/82 mmHg, and heart rate is 76/min. He has a mask-like facies and increased resting muscle tone with a catch-and-release pattern in both arms. Deep tendon reflexes are 2+ bilaterally without clonus. His Mini-Mental State Examination score is 21/30. Which of the following is the most likely diagnosis?