Image of the Month

A 22-year-old woman presented to the emergency department with a headache that had been going on for 5 days. She had been somnolent with vomiting for the past 18 hours. Her right leg began twitching rhythmically and continuously about an hour before her admission to the ED. She had suffered no trauma, recent illness, or previous episodes. To learn how imaging was key to her diagnosis and treatment, see Image of the Month, p. 22.