question: Q:A 50-year-old man presents to the emergency department with a severe headache. The patient reports that it started approx. 2 hours ago and has steadily worsened. He describes it as a stabbing pain localized behind his left eye. The patient reports that he has been having similar headaches several times a day for the past week, most often at night. He denies any nausea, vomiting, and visual or auditory disturbances. He has no significant past medical history. Current medications are a multivitamin and caffeine pills. The patient reports regular daily alcohol use but does not smoke. His temperature is 37.0°C (98.6°F), the blood pressure is 120/70 mm Hg, the pulse is 85/min, the respiratory rate is 18/min, and the oxygen saturation is 99% on room air. The patient is in moderate distress from the pain. The physical exam is significant for unilateral diaphoresis on the left forehead, left-sided rhinorrhea, and pronounced lacrimation of the left eye. The remainder of the physical exam is normal. Laboratory tests are normal. Non-contrast CT of the head shows no evidence of intracranial masses or hemorrhage. High flow oxygen and fluid resuscitation are initiated. Ibuprofen 200 mg orally is administered. Despite these interventions, the patient continues to be in significant pain. What is the next best step in management?? 
  {'A': 'Verapamil', 'B': 'CT angiography', 'C': 'Administer subcutaneous sumatriptan', 'D': 'RF ablation of the left trigeminal nerve', 'E': 'Deep brain stimulation of the posterior inferior hypothalamus'},