Evaluation of S-100b as a specific marker for neuronal damage due to minor head trauma

Management of patients with minor head trauma (MHT) continues to be debated in the literature. Measurement of S-100b in serum has been introduced into the discussion as an additional screening tool for intracerebral injuries because routine cranial computed tomography (CCT) of a large number of patients causes logistic difficulties, and the neurologic examination is often impaired by a high frequency of coincidental intoxication. The aim of our study was to determine the diagnostic value of measuring S-100b in the serum of MHT patients to identify risk groups. Additional validity should be aquired by a comparison with plasma levels of polymorphonuclear neutrophil (PMN) elastase an established general trauma marker. A series of 52 patients with MHT were included in the prospective study. At admission the patients underwent a routine CCT scan to detect intracerebral lesions, and blood samples were drawn to investigate circulating levels of S-100b and PMN elastase. For comparison, data for a positive control group of 10 severe head trauma patients (initial Glasgow Coma Scale score < 8) and for a negative control group with 20 healthy volunteers were obtained. The interval between MHT and admission to our hospital was 73.4 +/- 47.0 minutes. The initial S-100b serum levels of MHT patients were 0.470 +/- 0.099 ng/ml, those of the positive control group were 7.16 +/- 3.77 ng/ml, and those of the negative control group were 0.05 +/- 0.01 ng/ml. Relevant pathologic CCT scans were detected in 28.8% of MHT patients; one patient of that group was subjected to immediate surgical intervention (1.9%). At a cut-off point of 0.1 ng/ml, the sensitivity of positive S-100b levels reached 100% and the specificity 40.5%. Plasma levels of PMN elastase reached 60.52 +/- 10.75 ng/ml in the MHT group, 66.4 +/- 14.92 ng/ml in the severely head-injured group, and 23.26 +/- 1.53 ng/ml in the negative control group. Serum levels of S-100b seem to be a highly sensitive but not very specific marker for isolated neurotrauma. Measurement of this parameter may be helpful as an additional screening tool to identify high risk groups in the cohort of MHT patients.