The association of loss of consciousness (LOC) and/or amnesia with traumatic brain injury (TBI) identified on CT and TBI requiring acute intervention was evaluated in 2043 children <18 years old enrolled prospectively in a level 1 trauma center ED at University of California, Davis School of Medicine, CA. A documented history of LOC and/or amnesia was obtained in 801 (39%). Of 745 with LOC and/or amnesia and CT, 70 (9.4%) had TBI identified on CT, whereas only 11 (2.7%) of 414 without LOC and/or amnesia had CT evidence of TBI; 9.6% of patients with LOC had TBI requiring acute intervention compared to 1% of those without LOC. Of 142 patients with isolated LOC without other signs or symptoms of TBI, none had CT evidence of TBI and none required acute intervention. Isolated LOC and/or amnesia, without other findings suggestive of TBI, are not predictive of TBI on CT or TBI that requires acute intervention and should eliminate the need for CT. Isolated LOC is defined by the absence of vomiting, seizure, headache, skull fracture, altered mental status, neurologic deficit, or scalp hematomas. 
COMMENT. The diagnostic value of CT in the evaluation of a child with blunt head trauma must be weighed against the disadvantage of the transport of the patient, radiation exposure, possible need for sedation, and costs. Nevertheless, several guidelines recommend CT for all children with a history of LOC after blunt head trauma. This study minimizes the value of CT in cases of LOC with blunt head trauma, especially in patients without other signs or symptoms of head trauma. The authors caution that the findings in their center may not be generalized to all centers, and the data are insufficient for a meaningful analysis of cases less than 2 years of age and those secondary to child abuse. External validation of the results is suggested.
Mild head injury may result in cognitive deficits and behavior disorders, and a normal CT after head injury is predictive of a good prognosis and lack of subsequent mental deterioration. (Ped Neur Briefs April 1995).