Evaluation of the patient with nontraumatic headache: an evidence based approach.

This article reviews the literature on the diagnostic tools available to make a cost-effective yet appropriate diagnosis in the patient with an atraumatic headache in the emergency setting. The tools addressed include a good history and physical examination alone, third-generation CT, lumbar puncture, and MR imaging. The epidemiology and characteristics of the more common primary and secondary causes of headache are also reviewed, allowing the clinician to develop a better pretest probability of disease, and make a more educated decision as to when additional diagnostic testing is needed.