In pathology and anatomy the<unk> is the area surrounding an ischemic event such as thrombotic or embolic stroke. Immediately following the event, blood flow and therefore oxygen transport is reduced locally, leading to hypoxia of the cells near the location of the original insult. This can lead to hypoxic cell death (infarction) and amplify the original damage from the ischemia; however, the<unk> area may remain viable for several hours after an ischemic event due to the collateral arteries that supply the<unk>  zone. As time elapses after the onset of stroke, the extent of the<unk> tends to decrease; therefore, in the emergency department a major concern is to protect the<unk> by increasing oxygen transport and delivery to cells in the danger zone, thereby limiting cell death. The existence of a<unk> implies that salvage of the cells is possible. There is a high correlation between the extent of spontaneous neurological recovery and the volume of<unk> that escapes infarction; therefore, saving the<unk> should improve the clinical outcome.
Penumbra 
Watershed area 
Barrel cortex
Electuary
Periaqueductal gray
Surgisphere
Voxelotor
Subventricular zone