[Physiology and pathology of cerebral ischemia]

In this article the pathophysiology of cerebral ischemia is reviewed. The concept of penumbra is explained, and a distinction is made between ischemic necrosis, which occurs in the severely ischemic regions and is associated with loss of calcium and glutamate homeostasis, and programmed cell death, or apoptosis, which is more likely to occur in the moderately ischemic regions, evolves more slowly and depends on the activation of a sequence of genes. Despite this knowledge, it is pointed out that currently only a small percentage of stroke patients can access therapies. Some thoughts are provided on future research directions and therapies.