Head CT After Minimal Head Injury
Head CT After Minimal Head Injury
ABSTRACT & COMMENTARY
Source: Nagy KK, at al. The utility of head computed tomography after minimal head injury. J Trauma Inj Infec Crit Care 1999;46:268-270.
A group of trauma researchers at cook county hospital and Rush University prospectively studied patients who sustained blunt head injury with loss of consciousness (LOC) or amnesia with a Glasgow Coma Score (GCS) of 15. This group of patients is a subset of a registry maintained by their trauma service on all patients who sustain head injury. According to protocol, all patients with blunt trauma and LOC or amnesia underwent head computed tomography (CT). All patients with normal head CT scans were admitted for observation for at least 23 hours.
During a 35-month period, their trauma service admitted 1495 blunt head trauma patients with a history of LOC and amnesia. Nagy and colleagues state that 1170 of those had GCS of 15 on admission and formed the basis of the article. However, the data tables revealed that 30 of those patients had neither LOC nor amnesia, but had instead headache, nausea, vomiting, or seizures. Approximately 92% of the study group suffered LOC, with the remainder having amnesia (5.5%) or headache, nausea, vomiting, or seizures (2.6%). Presumably, the inclusion of patients with amnesia or seizures was meant to capture those who may have had unobserved LOC. The mechanism of injury was assault in 50%, and motor vehicle crash in 31%. Other mechanisms included were fall from height, auto-pedestrian incident, or struck by falling object.
Of the 1170, 39 patients (3.3%) had abnormalities on their head CT, the most common being intracranial bleeding (18 patients). Four patients required neurosurgical intervention, with two receiving elevation of depressed skull fractures and two having craniotomies for intracranial hemorrhage. Nagy et al state that a greater percentage of patients with abnormal CT scan had nausea, vomiting, dizziness, or seizures than patients with normal CT results (12.5% vs 2.1%). The converse, which would be the more useful finding, was not found. They did not report any increased risk of an abnormal CT in the presence of these symptoms. All patients with normal CT results were observed, but none suffered any neurologic deterioration during the observation period.
Nagy et al conclude that the head CT scan is useful and is indicated as a screening tool for blunt head injury patients with GCS of 15. Because of their study, they no longer observe patients who have both a normal head CT and a normal neurologic examination. Rather, these patients are now discharged from the emergency department after such isolated injuries.
Comment by Jeffrey W. Runge, MD, FACEP
This article is more evidence in a growing body of literature that not only justifies the use of head CT after blunt head injury with LOC, but suggests a new standard of care. What has been lacking in the literature is a reliable set of risk factors that would more precisely identify high-risk groups needing CT scans. A history or suspicion of LOC is the one risk factor that has been identified in the literature as raising risk sufficiently to mandate CT scanning. Many emergency physicians still prefer to observe patients with normal neurologic examinations for 24 hours, despite LOC or degree of energy transfer to the head.
Either approach can be defended and may depend more upon individual hospital resources than on evidence from the literature. Most trauma physicians would agree at this point in time that both CT and observation in the presence of a normal neurologic examination is excessive. The fixed cost of having a CT scanner in the hospital should be weighed against availability of observation beds and the practicality of the nursing staff doing those "q 2 hour neurochecks." Furthermore, we practice medicine in an atmosphere that will not tolerate a 3.3% error rate for a disease with severe and permanent sequelae, such as brain injury. Trauma physicians should insist upon using screening tools with the highest possible sensitivity for such diseases. Obtaining a CT scan in a patient with a head injury and LOC meets that criterion.
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