Minor head injuries are one of the most common injury types seen in emergency departments. CT scans, the standard method for diagnosis of possible neurocranial traumatic lesions, are costly and time-consuming and may not always be necessary. As reported in the December issue of Radiology, Dr. Marion Smits from Erasmus University Medical Center Rotterdam in the Netherlands and her colleagues evaluated six sets of international guidelines for using CT in patients with a minor head injury to see how well the guidelines identified patients at risk of developing complications.They reviewed data from 3181 patients who visited one of four hospitals within 24 hours after a blunt head injury to ascertain the mechanism of injury, traumatic findings from CT and neurosurgical intervention. Each set of guidelines provided very different sensitivity (how well people requiring CT scans were indentified). Only one set -- the European Federation of Neurological Societies guidelines -- reached a sensitivity of 100 percent for patients who were recommended for CT scanning and had traumatic findings. However, these guidelines also recommended that all of the patients with minor head injuries undergo CT, and therefore the specificity (how well patients that did not need CT scans were identified) was low. The Dutch national guidelines had the lowest sensitivity for identifying patients needing neurosurgical intervention, and would have missed almost 25 percent of the patients who needed CT scans (and who required neurosurgery). The best specificities were reached by the United Kingdom National Institute for Clinical Excellence Guidelines, which indicated that 37.2 to 56.6 percent of the patients would need to undergo CT. However, the sensitivity for these guidelines was low. In general, guidelines with higher sensitivities showed lower specificities.