Review Question - QID 216357

A 77-year-old man presents to the emergency department with a complaint of sudden onset weakness in his right upper extremity. At home, the patient thought he was simply dehydrated, but he rapidly began to have trouble speaking. When his wife noted this she brought him into the hospital. On arrival to the emergency department, the patient is not responding to verbal stimuli and only withdraws his left upper extremity and lower extremity to pain. His past medical history is notable for hypertension and atrial fibrillation treated with metoprolol, apixaban, and lisinopril. His temperature is 99.0°F (37.2°C), blood pressure is 170/100 mmHg, pulse is 95/min, and respirations are 16/min. The patient has a seizure and subsequently demonstrates agonal breathing. He no longer responds to painful stimuli. A fingerstick blood glucose is 122 mg/dL. Which of the following is the most likely etiology of this patient's symptoms?