Clinical Reasoning: An 18-year-old man with progressive headache and visual loss

An 18-year-old man presented to the emergency department after 3 weeks of intermittent headaches. He had experienced dull episodic central-parietal pain occurring 1 to 2 times a day and lasting for approximately 1 hour per episode. Headaches were associated with nausea and occasional projectile vomiting when the headaches were severe. He denied aura, photophobia, phonophobia, or blurred vision. Before arriving at the emergency department, he had his first generalized tonic-clonic event for several minutes. He did not have fever or weight loss. His medical and family histories were unremarkable. He denied having recently traveled.