A60-year-old man presents with a severe right-sided headache. he is conscious and alert. as you are assessing him, he tells you that the left side of his body feels weak. his blood pressure is 190/100 mm hg, pulse is 88 beats/min, and respirations are 14 breaths/min. his past medical history includes diabetes, arthritis, and hypertension. you should be most concerned with: