A 31-yr-old Asian woman comes to the emergency department because of a severe headache in the occipital region. She says the headache began suddenly about 1 h ago, and she describes it as "the worst headache of my life." She says the pain is constant and is accompanied by nausea but not vomiting. She denies visual symptoms, focal weakness, and problems with gait and balance.
She has frequently had similar headaches beginning about 2 yr ago. The headaches have increased in frequency this past week, and this episode is by far the worst. She says the headaches start suddenly, last about an hour, and are associated with palpitations, unexplained anxiety, and light-headedness. She has also had nausea and occasional swelling of the neck during these episodes. The headaches are usually associated with exertion or with straining during bowel movements but sometimes occur without any provocation. She has not been evaluated for these headaches before.