A 72-year-old woman presents to the emergency department with sudden-onset painless vision loss in her left eye. She describes the vision loss as occurring “like a curtain came down” over her eye earlier that morning. She denies any associated eye pain, flashes, or floaters. On further questioning, she admits to having been experiencing several weeks of intermittent, throbbing headaches over her temples, especially on the left side. These headaches are associated with scalp tenderness, particularly when combing her hair. She has also noticed recent jaw discomfort and fatigue while chewing.