Technologies for Identification of Biomarkers of TBI
For a comprehensive evaluation of TBI, multiple biomarkers need to be correlated. These include biomarkers in CSF and blood in addition to brain imaging, neurophysiological studies (EEG and evoked potentials) and tests of cognitive function. Since TBI is an evolving process monitoring may involve emphasis on certain tests that are practical at a particular stage of head injury.
Cerebral Microdialysis for Study of Biomarkers of TBI
Microdialysis was introduced as an intracerebral sampling method for clinical neurosurgery and has also been used as a research tool to measure the neurochemistry of acute human brain injury. Peripheral blood, CSF and cerebral microdialysis have been used for proteomic studies. TBI Biomarkers discovered by proteomics are complementary to those identified by traditional approaches and should be validated in preclinical or clinical samples. Clinical studies have provided ample evidence that intracerebral microdialysis monitoring is useful for the detection of overt adverse neurochemical conditions involving hypoxia/ischemia and TBI. There is some data strongly suggesting that microdialysis alterations precede the onset of secondary neurological deterioration following TBI. These promising investigations have relied on microdialysis biomarkers of disturbed glucose metabolism
(glucose, lactate, and pyruvate) and amino acids. Others have focused on trying to capture other important neurochemical events, such as excitotoxicity, cell membrane degradation, reactive oxygen species and nitric oxide formation, cellular edema, and BBB dysfunction. It remains one of very few methods for neurochemical measurements in the interstitial compartment of the human brain and will continue to be a valuable translational research tool for the future. The future success of microdialysis as a diagnostic tool in clinical neurosurgery depends heavily on the choice of biomarkers, their sensitivity, specificity, and predictive value for secondary neurochemical events, and the availability of practical bedside methods for chemical analysis of the individual biomarkers.
Intracerebral microdialysis catheters with a high molecular cutoff membrane have been used to harvest interstitial fluid for study of protein biomarkers. Monitoring of interstitial T-tau and Ap42 by using microdialysis may be an important tool when evaluating the presence and role of axonal injury following TBI (Marklund et al. 2009). These are biomarkers for AD as well and support the hypothesis that TBI as an important environmental risk factor for the development of AD.