Formation of brain edema after TBI in humans is one of the most critical factors in patient’s
morbidity and mortality.138 The most striking advantage of the brain compared to other organs of the
human body – its anatomical protection within the bony skull – also makes it most vulnerable to
extensive tissue swelling under pathophysiological conditions such as TBI. As a consequence of brain
edema, intracranial pressure (ICP) increases. If ICP exceeds a critical threshold, cerebral perfusion
pressure (CPP) critically decreases and results in an insufficient supply of oxygen and metabolites to the
brain. Subsequently, brain injury exacerbates as adjacent brain areas become ischaemic and brain
tissue shifts secondary to increased ICP (herniations).
Recent advances in brain imaging have revealed that one important component of swelling after TBI
is cytotoxic brain edema, i.e. shifting of water from extra- into intracellular spaces, which occurs, in
particular, in astrocytes and neurons.139 On the other hand, isolated posttraumatic cytotoxic edema
without concomitant vasogenic edema does not explain the massive brain edema which is observed in
patients after TBI.138 Vasogenic edema is the result of water seeping from cerebral vasculature to the
extracellular space as the BBB opens. This leads to a net influx of water into the brain and subsequent
formation of edema.