Does an isolated history of loss of consciousness or amnesia predict brain injuries in children after blunt head trauma?

BACKGROUND A history of loss of consciousness (LOC) is frequently used as an indication for cranial computed tomography (CT) in the emergency department (ED) evaluation of children with blunt head trauma. OBJECTIVE We sought to determine whether an isolated LOC and/or amnesia is predictive of traumatic brain injury (TBI) in children with blunt head trauma. METHODS We prospectively enrolled children <18 years old presenting to a level I trauma center ED between July 1998 and September 2001 with blunt head trauma. We evaluated the association of LOC and/or amnesia with 1) TBI identified on CT and 2) TBI requiring acute intervention. We defined the latter by a neurosurgical procedure, antiepileptic medication for >1 week, persistent neurologic deficits, or hospitalization for > or =2 nights. We then investigated the association of LOC and/or amnesia with TBI in those patients without other symptoms or signs of TBI ("isolated" LOC and/or amnesia). RESULTS Of eligible children, 2043 (77%) were enrolled, 1271 (62%) of whom underwent CT; 1159 (91%) of these 1271 had their LOC and/or amnesia status known. A total of 801 (39%) of the 2043 enrolled children had a documented history of LOC and/or amnesia. Of the 745 with documented LOC and/or amnesia who underwent CT, 70 (9.4%; 95% confidence interval [CI]: 7.4%, 11.7%) had TBI identified on CT versus 11 of 414 (2.7%; 95% CI: 1.3%, 4.7%) without LOC and/or amnesia (difference: 6.7%; 95% CI: 4.1%, 9.3%). Of the 801 children known to have had LOC and/or amnesia (regardless of whether they underwent CT), 77 (9.6%; 95% CI: 7.7%, 11.9%) had TBI requiring acute intervention versus 11 of 1115 (1%; 95% CI: 0.5%, 1.8%) of those without LOC and/or amnesia (difference: 8.6%; 95% CI: 6.5%, 10.7%). For those with an isolated LOC and/or amnesia without other signs or symptoms of TBI, however, 0 of 142 (95% CI: 0%, 2.1%) had TBI identified on CT, and 0 of 164 (95% CI: 0%,1.8%) had TBI requiring acute intervention. CONCLUSIONS Isolated LOC and/or amnesia, defined by the absence of other clinical findings suggestive of TBI, are not predictive of either TBI on CT or TBI requiring acute intervention. Elimination of an isolated LOC and/or amnesia as an indication for CT may decrease unnecessary CT use in those patients without an appreciable risk of TBI.