Figure 1.

Proposed secondary cell death mechanism after TBI. A sensitive balance in neurotrophic factor secretion and cytokine expression dictates the fate of injured neurons towards pro-survival (early stage) and pro-death (chronic stage) cellular processes after TBI. Upregulation of neurotrophic factors and cytokines may renderneuroprotectionin the early stage, whereas downregulation of neurotrophic factors coupled with continued upregulation of specific pro-death cytokines, as well as the onset of oxidative stress, massive edema, and alterations in endogenous neurotransmitter function may promote neurodegeneration in the chronic stage.