Prefactory comments: promise and enigma of biomarkers for brain injury

Traumatic brain injury (TBI) represents one of the greatest unmet needs in medicine and public health (Maas et al., 2008). It is a major cause of death and disability and leads to great personal suf-fering to victims and relatives, as well as huge direct and indirect costs to society (Finkelstein et al., 2006; Faul et al., 2007; Gustavsson et al., 2011). TBI is considered “the most complex disease in our most complex organ. ” We now recognize that TBI is not just an acute event but can trigger a chronic process, with progressive injury over hours, days, weeks, months, and even years. The challenges posed by