S-100βReflects the Extent of Injury and Outcome, Whereas Neuronal Specific Enolase Is a Better Indicator of Neuroinflammation in Patients With Severe Traumatic Brain Injury

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Abstract
It has been hypothesized that immunoactivation may contribute to brain damage and affect outcome after traumatic brain injury (TBI). In order to determine the role of inflammation after TBI, we studied the interrelationship of the immune mediators sICAM-1 and IL-6 with the levels of S-100β and neuronal specific enolase (NSE), both recognized markers of brain damage. In addition, the extent and type of cerebral injury and the neurological outcome were related to these measured markers of injury. An evident elevation of S-100β (range of means: 2.7-81.4 ng/mL) and NSE (range of means: 2.0-81.3 ng/mL) was observed in CSF of all 13 patients during the first 3 post-traumatic days and decreased over 2 weeks. In parallel, the production of sICAM-1 (range of means: 0.7-11.9 ng/mL) and IL-6 (range of means: 0.1-8.2 ng/mL) was also markedly enhanced in CSF. The CSF means of S-100β and NSE per patient correlated with IL-6 (r = 0.60, p < 0.05; and r = 0.64, p < 0.05, respectively), whereas the corresponding means in serum showed a significant correlation only between NSE and IL-6 (r = 0.56, p < 0.05). Maximal CSF values of NSE and sICAM-1 correlated with each other (r = 0.57, p < 0.05). The contusion sizes assessed on the CT scans correlated with the means of S-100β (r = 0.63, p < 0.05) and NSE (r = 0.71, p < 0.05) in CSF and with the mean of S-100β in serum, although not statistically significant (r = 0.52, p = 0.06), but not with serum NSE. Interestingly, linear regression analysis demonstrated that means of S-100β in CSF (r = 0.78, p = 0.002) and serum (r = 0.82, p < 0.001) correlated with the GOS. These results indicate that the elevation of these parameters in CSF depends on the extent of injury and that S-100β may be a predictor of outcome after TBI, whereas NSE reflects better the inflammatory response.