An 82-year-old woman is brought to the emergency department for evaluation of sudden onset left-sided weakness and
lethargy. The patient lives at home with her son, who found the patient
lethargic and unable to move the left side of her
body. The son states over the past year, the patient has been forgetting names of common people as well as losing her abilities to perform
activities of daily living. She recently became lost in the parking lot of a grocery store she has been shopping at for decades. She has no past medical history. Her temperature is 37°C (98.6°F),
pulse is 101/min and regular, and
blood pressure is 171/94 mmHg. The patient appears
somnolent but is arousable to voice and pain. Physical examination reveals marked weakness of the left upper and left lower extremity with associated decreased sensation in the left arm and leg. The patient’s eyes are currently deviated towards the right. A noncontrast CT of the
head is shown below:
Reproduced from: Radiopaedia
Which of the following best describes the most likely etiology of this patient’s clinical presentation?
