Review Question - QID 214570

A 27-year-old man presents to the emergency department with a headache. He has had headaches in the past which have usually resolved on its own. This one is persistent and severe and is located over the front of his head. It came on gradually and has not improved despite resting in a cool, dark room. His temperature is 97.7°F (36.5°C), blood pressure is 121/81 mmHg, pulse is 83/min, respirations are 18/min, and oxygen saturation is 98% on room air. Physical exam reveals a healthy young man. The lights are off in the exam room as it causes him discomfort. The patient has a stable gait and normal strength/sensation in his upper and lower extremities. Cranial nerves are grossly intact. The patient is given ketorolac, acetaminophen, prochlorperazine, diphenhydramine, and a liter of IV fluids. Two hours later, he complains of a persistent headache with only mild improvement of symptoms. Which of the following is the most appropriate next step in management?