After seconds to minutes of cerebral ischaemia, the ischaemic cascade is initiated. This is a series of biochemical reactions in the brain and other aerobic tissues, which usually goes on for two to three hours, but can last for days, even after normal blood flow returns.
The goal of acute stroke therapy is to normalise perfusion and intervene in the cascade of biochemical dysfunction to salvage the penumbra as much and as early as possible.
Although it is called a cascade, events are not always linear (figure 2).