Review Question - QID 213853

A 78-year-old woman presents to the emergency department with sudden onset neurologic symptoms. She states that she suddenly felt "strange", thus prompting her presentation. She endorses an ongoing headache. The patient has a past medical history of hypertension, diabetes, and atherosclerosis. Her temperature is 97.6°F (36.4°C), blood pressure is 177/91 mmHg, pulse is 90/min, respirations are 15/min, and oxygen saturation is 98% on room air. Physical exam is notable for numbness on the patient's left lower face. The patient's headache improves with the administration of acetaminophen. She has decreased pain and temperature sensation on the right side of her body. She demonstrates an ataxic gait when walking to the bathroom. Her gag reflex is not present as well. Which of the following is the most likely diagnosis?