Pathobiology of injury after stroke: the neurovascular unit and beyond.

Throughout the history of research on stroke pathophysiology, focus has shifted from purely vascular concepts to the insight that a complex interplay of biochemical and molecular mechanisms involving practically any cell type of the brain ("neurovascular unit") partakes in either salvage or demise of the tissue after a stroke. In addition, it was realized that peripheral immune cells play important roles, not only after their invasion into the brain but also because of stroke-induced effects on the immune system that can result in infections. Indeed, outcome of stroke patients is not only dictated by nonmodifiable factors, such as severity of stroke, age, or premorbidity, but also by modifiable factors largely related to medical complications, such as infections and possibly sarcopenia. The highly successful concept of stroke units attests to the benefits of treating stroke comprehensively. Breakthroughs in improving outcome after stroke will only result from approaches that target not only the brain, but also systemic effects of stroke.