CT Angiogram — Circle of Willis

A 52-year-old woman presents to the emergency department with a sudden-onset, severe "thunderclap" headache described as the worst of her life, accompanied by neck stiffness and photophobia. Non-contrast CT head performed within 2 hours shows hyperdense material in the basal cisterns consistent with subarachnoid hemorrhage. CT angiogram reveals a saccular aneurysm at the structure marked **A** in the Circle of Willis diagram. Which of the following clinical findings would be MOST SPECIFIC to rupture of an aneurysm at this location?