An 86-year-old woman is brought to the emergency department due to progressive confusion and lethargy for the past several hours. The patient has a history of Alzheimer dementia and her family reports that she has been gradually declining in mental and physical capacity over the last 6 months. She also has had several falls and requires assistance with daily activities. Her other medical problems include hypertension, myocardial infarction, chronic atrial fibrillation, and osteoarthritis. Her medications include aspirin, losartan, metoprolol, sirnvastatin, and donepezil. The patient's anticoagulation therapy was stopped 6 months ago after an episode of rectal bleeding.Temperature is 38 C (100.4 F), blood pressure is 1701100 mm Hg, and pulse is 70fmin and irregularly irregular. On physical examination, the patient is somnolent but arousable. She withdraws from painful stimuli applied to her right side but not to her left. ECG shows atrial fibrillation.Noncontrast CT scan of the head is shown in the image below
