Edema that is characterized by cell swelling, with a parallel reduction in the volume of fluid in the extracellular space. This type of edema is seen in most commonly with cerebral ischemia, resulting from occlusion or hemorrhage of cerebral vasculature. The primary mechanism is loss of ATP driving the sodium-potassium ATPase pump, due to local hypoxia resulting from ischemia. Thus sodium accumulates in the intracellular space, and created an osmotic gradient for water to enter the cells. The edema consists of sodium and water, and protein is not present. By definition, the BBB (blood brain barrier) is still intact, at least initially. Both gray matter and white matter are affected by this type of edema.