A 35-year-old woman comes to the physician because of headache, vomiting, and fever for the past 24 hours. Temperature is 103 F. Examination shows weakness of the left upper extremity and nystagmus; the optic fundi cannot be visualized. Kernig and Brudzinksi signs are positive. Which of the following is the most appropriate next step in diagnosis?
Blood cultures
CT of the head
EEG
Lumbar puncture
Observation acutely
