Mild head injury: reliability of early computed tomographic findings in triage for admission

Objective: To search the literature for case reports on adverse outcomes in patients with mild head injury where acute computed tomography (CT) findings had been normal. Methods: Mild head injury was defined as head trauma involving amnesia or loss of consciousness, but where neurological findings are normal on arrival at hospital (GCS 15). The scientific literature was systematically searched for case reports where an early CT was normal and the patient deteriorated within two days. In these cases, early discharge despite a normal CT head scan would have been hazardous. Results: Two prospective studies were found that investigated the safety of early CT in 3300 patients with mild head injury, as were 39 reports on adverse outcomes describing 821 patients. In addition, 52 studies containing over 62 000 patients with mild head injury were reviewed. In total, only three cases were deemed to have experienced an early adverse outcome despite a normal CT and GCS 15 on initial presentation. In another eight cases with incomplete descriptions, the interpretation was doubtful. Many reports of complications were not relevant to our question and excluded. These reports included cases with more severe head injury/not GCS 15 at presentation, complications that occurred after more than two days, or initial CT findings that were not fully normal. Conclusion: Very few cases were found where an early adverse event occurred after normal acute CT in patients with mild head injury. The strongest scientific evidence available at this time shows that a CT strategy is a safe way to triage patients for admission.