INDICATIONS

Head CT is one of the most common imaging studies ordered from the ED. It is indicated in the evaluation of patients with head injury as well as in a variety of nontraumatic presentations.

In most U.S. centers, the clinical threshold for obtaining a head CT in the traumatized patient is very low. Although three clinical decision rules have been developed to identify low-risk patients for whom imaging is unnecessary, none is in widespread use. The criteria identified by the Canadian Head CT Investigators (1), the National X-Ray Utilization Investigators (2), and the New Orleans Group (3) are listed in Table 30.1.

Head CT is also used in the evaluation of the patient who presents with headache, altered mental status, suspected stroke, or other acute neurological abnormalities. As in patients with head injury, head CT is used rather liberally in EDs in the United States, and although some guidelines for its utilization exist, they are generally the product of consensus panels rather than randomized controlled trials. In patients with altered mental status or acute neurological abnormalities, there is little controversy about the need for emergent head CT scanning. In patients with headache, it is generally recommended that emergent CT be limited to patients with certain high-risk features to their presentation (4).