Relationship of Serum S100B and Intracranial Injury in Children with Accidental Closed Head Trauma

S100B, a calcium-dependent protein produced by astroglial cells in the central nervous system (CNS) and by chondrocytes, functions as both a neurotrophin and neurotoxin. It has a half-life in the systemic circulation of approximately six hours. We examined whether serum levels of S100B would be predictive of intracranial injury (ICI) in children, as detected by cranial computed tomography (CT), in children with closed head trauma (CHT). In addition, we evaluated the effect of long bone fractures on the level of S100B in children with both CHT and extracranial injuries such as long bone fractures. One hundred fifty-two children, who presented to the Pediatric Emergency Department of Yale -New Haven Children's Hospital, within six hours of accidental CHT, and required CT to exclude ICI, were prospectively enrolled. After informed consent from a caregiver, samples were obtained by venipuncture and analyzed for a quantitative serum level of S100B. Of the 152 children enrolled in this study, 24 had an ICI. Mean S100B levels were significantly greater in children with ICI (0.212 μg/L vs. 0.084 μg/L; p<0.001), in children with long bone fractures (0.220 μg/L vs. 0.083 μg/L; p<0.001), and in children who were non-white (0.127 μg/L vs. 0.081 μg/L; p=0.03). Sixty-two percent of children with ICI had venipuncture performed more than 120 minutes after head injury. After controlling for time of venipuncture, fractures, and race, mean S100B levels were still greater in children with ICI (0.409 μg/L vs. 0.118 μg/L; p<0.001). The discriminatory value of S100B to detect ICI, as determined by the area under the receiver operator characteristics (ROC) curve, was 0.67. Further study of S100B is necessary to determine whether this biochemical marker could serve as a useful adjunct in the evaluation of children with CHT.